durability of paper and writing

Proceedings of the International Conference

Durability of Paper and WritingNovember 16–19, 2004, Ljubljana, SloveniaOrganized in the frame of the EC 5th Framework Programmeprojects MIP, Papylum and InkCor

Proceedings of the International Conference Durability of Paper and Writing

November 16–22, 2004, Ljubljana, Slovenia

Editors: Jana Kolar, Matija Strlic and John B. G. A. Havermans

Published by National and University Library, Ljubljana, Slovenia, 2004

CIP - Kataložni zapis o publikacijiNarodna in univerzitetna knjižnica, Ljubljana

7.025.3/.4:676.2(063)(082)7.025.3/.4:667.4/.5(063)(082)676.017(063)(082)

INTERNATIONAL Conference Durability of Paper and Writing (2004 ;Ljubljana)LjuProceedings of the International Conference Durability of Paperand Writing, November 16-19, 2004, Ljubljana, Slovenia / [editorsJana Kolar, Matija Strlic and John B. G. A. Havermans]. - Ljubljana :National and University Library, 2004

ISBN 961-6162-98-51. Durability of paper and writing 2. Kolar, Jana

216440320

7Durability of paper and writing

MIP – NOT JUST A EUROPEAN NETWORKJohn HavermansTNO, Delft, The Netherlands

e-mail [email protected]

1. IntroductionNetworking of communities of researchers,infrastructure owners and users is one of the importantinstruments the European Commission DG Research isoffering in order to establish co-operation and co-ordination between existing facilities, researchers, end-users, industrialists, manufacturers and designers. AEuropean Thematic Network aims therefore to create anoptimum use of infrastructures, to avoid unnecessaryduplication, and to offer access to a broader communityof researchers.

One of the causes of paper deterioration is due to theapplied corrosive ink. The corrosion effect can begeneralised as the effects of transition metals in paper.Other related deterioration processes take place in thepresence of metal clips and other metal items. It isobvious that all these different items related to MetalsIn Paper, with acronym MIP, is being investigated formany years, at conservation workshops, researchinstitutes, universities and suppliers. Research is carriedout to gain a better understanding and to prevent outheritage against deterioration.

Since 2003 a European Thematic Network has beenestablished (contract number EVK4-2002-20010).

2. Organization of MIPFour theme groups have been formulated in ourthematic network now in order to improve thecommunication between researchers, end-users andsuppliers. Furthermore the network aims to defineknowledge gaps and to foster the bilateral co-operationin order to avoid duplicate of research on Europeanlevel. Dissemination of the work will be performed bysymposia and the website www.miponline.org.

In the Theme group 1 (TG-1), fundamental scientificaspects of paper degradation are discussed, focussingprimarily on diagnostics and analytical techniques,studies of degradation processes (including endogenousand exogenous factors), and methodologies for paperstability evaluation. The chair for TG-1 is Dr MatijaStrlic from Slovenia (e-mail: [email protected]). Itwas not accidentally that Dr Strlic is chairing this groupas he is also co-ordinator of the EU research projectPapylum, aiming to study chemiluminescent pheno-mena during paper degradation. Chemiluminescenteffect is often observed in one of the stages of de-gradation of paper by transition metals. . The input ofPapylum’s knowledge to MIP benefits therefore thecommunity of conservation science.

Within the applied research and applications we havethree theme groups.

In our network we see the conservation of objectsdivided in two parts. Active and Preventive conser-vation, while active conservation is split in the chemicaland physical aspects.

Theme Group 2 (TG-2) deals with the chemical aspectsof Active Conservation. Items as conventional methods,inhibitors and deacidification are discussed here (TG-2). The co-ordinator of TG-2 is Dr Jana Kolar fromSlovenia (e-mail: [email protected]). Dr Kolarcoordinates also a very important EU research projectInkcor. This research will have an impact on our currentknowledge and the prevention of the degradation ofobjects affected with so called metal-tannin inkcorrosion. It is gaining new knowledge about oxidativedegradation of cellulose and stabilisation of deterioratedobjects by a combination of improved non-aqueousdeacidification and antioxidants.

The Physical Aspects of Active Conservation is theitem being discussed in Theme Group 3. TG-3discussion items include paper splitting, strengthening,leaf-casting and cleaning. This TG is chaired by DrManfred Anders from Germany (e-mail:[email protected]). Dr Anders is scientific manager of acompany ZFB, ZENTRUM FÜR BUCHERHALTUNGGmbH, which was established as a private company inthe beginning of 1998 after having served as the Centrefor Book Conservation of the German Library inLeipzig for nearly 35 years. The company has ex-periences with numerous conservation technique, forexample the mechanical splitting of paper materials.

Conservation alone will not always prevent materialsfor further deterioration. Theme Group 4, deals withPreventive Conservation issues. Environmental storageconditions, boxing, and other issues are the principalitems belonging to TG-4, which is chaired by Dr JohnHavermans from The Netherlands (e-mail:[email protected]). Dr Havermans coordinatedpreviously a EU research project on the effects of airpollutants on de degradation of paper and carried outmany studies related to deacidification and storageconditions.

3. MIP membersThe MIP thematic network has officially 21 members.They are listed below.

Besides official MIP members, there are numerousassociated members. For example, a good relation has

8 Durability of paper and Writing

been established between MIP and the French ResearchGroup on Iron Gall Ink Corrosion and the Polishresearch group where for example kinetics of the acidcatalysed hydrolyses of cellulose is being studied.

Other output will be a memorandum of understandingwhere figures are being presented on the need ofconservation actions and conservation research. Basedon the input of the members and members personal

network, information is collected andsummarized. Besides contributing topolicy, research community will benefitfrom the memorandum.

As a result of the MIP thematic network,three new 6th framework projects weresubmitted to a recent call published byEC within its 6th framework programme.Proposals with draft acronyms Papertreatand SurveNIR vere favourably evaluatedby the evaluators and entered thenegotiation phase.

5. Time goes fastA 36-month running thematic networksounds long, however officially ends inFebruary 2006. Nevertheless we will putour effort in organizing a joint inter-national event again, to end our networkin May 2006. Information on the organi-zation and location will be presented atour website www.miponline.org.

This network is not just a network. MIP iscreated for our future. It gains contacts,new ideas and future co-operation andwill define gaps in knowledge andresearch.

6. AcknowledgementThe author and members of MIP grate-fully acknowledge the support of theEuropean Community, 5th FrameworkEnergy, Environment and SustainableDevelopment Programme, contract no.EVK4-CT-2002-20010 (MIP). This paperis the sole responsibility of the author anddoes not represent the opinion of theCommunity. The Community is notresponsible for any use that might bemade of the data appearing herein.

7. References1. MIP website: www.miponline.org2. Papylum website: www.papylum.uni-lj.si3. Inkcor website: www.infosrvr.nuk.uni-lj.si/jana/Inkcor/index.htm4. EU cultural heritage conference, London 2004: www.ucl.ac.uk/

sustainableheritage/ec-conference/index.html5. International Event on Paper durability: www.paperdurability.org6. Community Research & Development Information Service:

www.cordis.lu

Table 1: Based on EU policy, we do welcome all new interest members,especially active ones.

TNO JohnHavermans [email protected]

National Archives Jonasof Sweden Palm [email protected] Archives Tedof the Netherlands Steemers [email protected] für Manfred [email protected] GmbH AndersMuseu Moli Paperer Maria-Carme [email protected] de Capellades SistachSlovak Technical Michal [email protected] CeppanUniversity of Jean A. [email protected] BrownGöteborg Oliver [email protected] LindqvistSlovak National Jozef [email protected] HanusNational Archives Jaan [email protected] Estonia LetharuEVTEK Institute Istvan [email protected] Art and Design KecskemetiJagiellonian Andrzej [email protected] BaranskiNational and Jana [email protected] Library KolarNational Library Nina [email protected] Norway Hesselberg-WangArt Hans [email protected] ScholtenInstituut Collectie Han [email protected] NeevelUniversity of Matija [email protected] StrlicCNR Materiali Yeghis [email protected] KeheyanQuillet S. A. Lionel [email protected]

QuilletUniversity of Veronique [email protected] Rochelle RouchonMuseum Boijmans Monica [email protected] Beuningen Marchesi

4. MIP outputSo far, different symposia we organized in order toexchange knowledge. For example we organized asymposium in Capellades (Spain) in February 2004 andin La Rochelle (France) in July 2004. Also joint eventsare organized to obtain input and output for ournetwork. For example Healthy Indoor Environment inSeptember 2004 (The Hague, The Netherlands) wherethe MIP preventive conservation group is combinedwith other symposia and in November 2004, wherePapyplum, Inkcor and MIP organize a jointinternational event in Ljubljana, Slovenia.


INKCOR PROJECT – STABILISATION OF IRON GALL INKCONTAINING PAPERJana KolarNational and university library, Ljubljana, Slovenia

* corresponding author: [email protected]

1. IntroductionIron gall ink is probably the most important ink inWestern history, widely used from the middle ages to20th century1. Due to the inks’ corrosive properties, thedamage caused so far is extensive, with 60–70% ofpriceless Leonardo da Vinci oeuvre showing signs ofdegradation2 and Bach’s hand-written music virtuallyfalling apart.3

– Numerous iron gall ink recipes from the collectedhistorical sources were evaluated and entered into theICN Art Technological Sources database.4

– Ink corrosion database, a tool for visual assessment ofnumerous historical artefacts was created and will aidconservators in describing and documenting thedocuments.

– Model rag papers were produced and their properties,such as pH, ageing stability, brightness stabilityduring thermal ageing, metal content, etc,determined. They were used for evaluation of paperstabilisation treatments throughout the project.

– Another study aimed at the evaluation of thosefactors, which result in the variable conditions ofhistorical documents containing iron gall ink.Namely, while some are completely destroyed, othersmay be in excellent condition even centuries aftertheir creation. In order to establish the mainproperties, common to severely degraded documents,the effects of the type and quantity of transitionmetals in ink, as determined by in-air PIXE method,pH of the ink containing paper, grammage of paper,its absorptivity and the width of ink lines wereevaluated against the degree of corrosion. Usingmultiple linear regression analysis, a correlation hasbeen obtained between the width of the applied inklines, pH, grammage of paper and the extent of inkcorrosion. From these properties, which can be non-destructively obtained from most historicaldocuments, it is therefore possible to predict thestability of historical iron gall ink containing paper.5

– Simple identification test for iron, developed by ICN,was evaluated and a novel one, aimed atidentification of copper ions was developed, enablingconservators to identify the corrosive inks.6

– In-air PIXE method was used to determine thecontent of transition metals in 99 documents7. Ironcontent in ink containing paper reached values ashigh as 1656 mmol g-1, while it did not exceed 38mmol g-1 in areas, which did not contain iron gall ink.The results furthermore demonstrate that inks,containing substantial amounts of copper were usedthroughout the time span covered by our study.8

Molar ratio of copper to iron surpassed 10% in 32manuscripts, while it was higher than 60% it 6documents. Molar ratios of other potential catalysts9

were lower, not exceeding 5% for chromium, 6% formanganese and 10% for cobalt.

– It was demonstrated that, under alkaline conditions,copper ions are much better catalysts of peroxidedecomposition than iron ions.10-12 They may be the

Figure 1: Letter by Galileo Galieli. Collection NationaalArchief, The Netherlands.

Due to the alarming data concerning deteriorationcaused by the corrosive ink, several European partnersjoined forces within a fifth framework project InkCor –Stabilisation of iron gall ink containing paper. The mainobjectives of InkCor project are to significantly improvethe present know-how of the phenomenon of inkcorrosion and to establish best non-aqueous conser-vation practices for iron gall ink containing documents,enabling their preservation and undisturbed access.Consortium consists of eight partners: National andUniversity Library, Slovenia; University of Ljubljana,Faculty for Chemistry and Chemical Technology,Slovenia; Institut “Jožef Stefan”, MicroanalyticalCentre, Slovenia; The Netherland Institute for CulturalHeritage; Nationaal Archief, The Netherlands; TeylersMuseum, The Netherlands, ZFB – Zentrum fuerBucherhaltung, Germany; and Musée du Louvre,France. Partner structure is interdisciplinary, consistingof art historians preservation officers a panel ofconservators representing museums, archives andlibraries, conservation and analytical chemists and aphysicists, as well as a SME performing massdeacidification, all specializing on a certain aspect ofiron gall ink corrosion.

2. ResultsExcellent co-operation between European partners withdifferent expertise resulted in a range achievements:


main source of damage exerted to numerous iron gallink containing documents, once deacidification hadbeen performed. Efficient antioxidants shouldtherefore not focus on stabilisation of iron ions alone.

– Evaluation of non-aqueous deacidification systemsdemonstrated that a solution deacidification ispreferred over a suspension system. Research withinInkCor project led to several improvements of theexisting commercial process for mass deacidificationof books, which have been already implemented bythe SME partner, Zentrum fuer Bucherchaltung(ZfB). The quality of deacidification agentmagnesium titanium ethoxide was improved,resulting in diminished yellowing of treated papers.Conditioning room was built to allow for fasterconversion of deacidification agent into thecorresponding carbonates.

– In order to develop a non-aqueous method forstabilisation of iron gall ink containing paper, anumber of antioxidants was evaluated. The mostpromising turn out to be a group of peroxidedecomposers, which are able to inhibit oxidativedecay irrespectively of the type of transition metalwhich catalyses it.Results demonstrate that while deacidification usingmagnesium ethoxide in ethanol (0.05 mol L-1)decreased degradation of iron gall ink containingpaper by 50 ± 10%, treatment with a non-aqueousInkCor process resulted in 80 ± 10% slowerdegradation (Figure 1), as compared to the untreatedpaper. In addition to stabilising paper containing irongall inks, new process inhibits degradation of thepaper itself (without iron gall ink) in alkalineenvironment,8 thus offering additional benefits of theproposed potential stabilisation method. As a resultof the research undertaken within the project ZfB,National and University Library of Slovenia andUniversity of Ljubljana, Slovenia jointly submitted apatent for a new non-aqueous paper stabilisationmethod containing antioxidants.

After three years of research, the project will draw to aclose in February 2005. Until then, the novel treatmentfor papers containing corrosive iron gall inks will beextensively evaluated by the researchers and end-usersin the project, in order to determine whether it can besafely used for stabilisation of historical artefacts.

3. AcknowledgementThe authors gratefully acknowledge the support of theEuropean Commission, Fifth Framework Programme,Key Action “City of tomorrow and cultural heritage”within the Energy, Environment and SustainableDevelopment, Contract n° EVK4-CT-2001-00049,project InkCor. The work is the sole responsibility ofthe authors and does not represent the opinion of theCommunity. The Community is not responsible forany use that might be made of the data appearingherein.

4. References1. N. Jones, Monster ink, New Scientist, 2002, 175, 38–42.2. S. Scholten, Position Paper, H.v.d. Windt, (ed.), Proceedings

European Workshop on Iron-Gall Ink Corrosion, InstituutCollectie Nederland, Amsterdam, 1997, 9–12.

3. H. Böhrenz, Problematik der Erhaltung vonTintenfrassgeschädigten Bach-Autographen in derStaatsbibliothek zu Berlin – Preussischer Kulturbesitz. in: G.Banik, H. Weber, H., ed., Tintenfrassschäden und ihreBehandlung, Stuttgart, DE, W. Kohlhammer GmBH, 1999, 245–264.

4. A. Stijnman, Historical Iron Gall Ink Recipes, in: B. Reissland,A. E. Buellow, A. Page, A. Pataki, eds., IADA 2003, IADA,Goettingen, DE, 2003, 44.

5. J. Kolar, A. Štolfa, M. Stlič, M. Pompe, B. Pihlar, M. Budnar,B. Reissland, Historical iron gall ink containing documents.Properties affecting their condition, New J. Chem., submitted.

6. H. Neevel, Non-destructive identification of corrosive inks, in: J.Kolar, M. Strlic, J. Wouters, eds., Proceedings of the ICOM-CCGraphic Documents Meeting, NUK, Ljubljana, 2004, 67–68.

7. M. Budnar, J. Simčič, M. Uršič, Z. Rupnik, J. Kolar, M. Strlič,Determination of elemental contentrations of iron gall inkcomponents by PIXE, J. L. Duggan, I. L. Morgan, eds., 17th Int.Conference Application of Accelerators in Research andIndustry, American institute of physics, 2003, 436–439.

8. J. Kolar, M. Strlič, M. Budnar, J. Malešič, V. S. Šelih, J. Simčič,Stabilisation of corrosive iron gall inks, Acta ChimicaSlovenica, 2003, 50, 763–770.

9. M. Strlič, J. Kolar, V. S. Šelih, D. Kočar, B. Pihlar, Acomparative study of several transition metals in Fenton-likereaction system at corcum-neutral pH, Acta Chimica Slovenica,2003, 619–632.

10. V. S. Šelih, M. Strlič, J. Kolar, Catalytic Activity of TransitionMetals During Oxidative Degradation of Cellulose, in: J. Kolar,M. Strlic, J. Wouters, eds., Proceedings of the ICOM-CCGraphic Documents Meeting, NUK, Ljubljana, SI, 2004, 71–72.

11. M. Strlič , V. S. Šelih, J. Kolar, Methodology to Study the Roleof Transition Metals During Oxidative Degradation ofCellulose, in: G. Baudin, J. Fellegi, G. Gellerstedt, S. Katuscak,I. Pikulik, J. Paris, eds., Chemical Technology of Wood, Pulpand Paper, Slovak University of technology, Bratislava, 2003,385–386.

12. V. S. Šelih, M. Strlič, J. Kolar, Catalytic Activity of TransitionMetals During Oxidative Degradation of Cellulose,in: G.Baudin, J. Fellegi, G. Gellerstedt, S. Katuscak, I. Pikulik, J.Paris, eds., Chemical Technology of Wood, Pulp and Paper,Slovak University of technology, Bratislava, 2003, 460–461.

13. A. M. Emsley, G. C. Stevens, Kinetics and Mechanisms of thelow temperature degradation of cellulose, Cellulose , 1994, 1,26–56.

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Figure 2: Rates of degradation of untreated (O), deacidifiedwith magnesium ethoxide (Mg (OEt)2) and stabilised withInkCor process during ageing at 80 oC and 65% RH. Therates were calculated using the Eckenstam model.13


PAPYLUM PROJECT: CHEMILUMINESCENCE – A NOVEL TOOL INPAPER CONSERVATION STUDIESMatija Strlič*University of Ljubljana, Faculty of Chemistry and Chemical Technology, Ljubljana, Slovenia


1. IntroductionDeacidification of paper is one of the most oftenperformed active conservation procedures. The need foroptimal deacidification is well justified considering thevast quantities of acidic paper in Western libraries andarchives, e.g. in Poland.1 Due to the production process,papers produced in the period ca. 1850–1990 are acidic,and the rate of their degradation is such that it is quitepossible that in the next century or two, most of theartistic, written and printed documentation on paperfrom the period will irreversibly fall into pieces (Figure1) if no action is taken.

cellulose and paper led to optimisation of aqueousdeacidification techniques and new guidelinesregarding evaluation of paper stability, thus increasingthe accessibility of cultural heritage on paper.

2. ResultsThe consortium, driven by expertise of five researchlaboratories, two of them in end-user institutions, andone in an institute involved in instrument production forthe scientific market, ensured a highly focussedapproach leading to the following results:

– Construction of a state-of-the art chemiluminometricinstrument, the first of its kind. The measurementprocedure is straightforward: a sample (even acomplete object) is simply inserted into theinstrument and the emitted light can readily bemeasured – degradation of paper at room temperaturecan virtually be seen. The instrument allows the useof humid atmosphere, which is known to affectdegradation of cellulose and paper, and it also allowsthe observation of samples without destructivesampling. The instrument is a valuable addition to theconservation scientist’s laboratory, and is alreadycommercially available.3 Its use extends well beyondconservation research, as it may be used fordegradation studies of a variety of organic materials,including e.g. food.

Figure 1: A degraded acidic paper item from the 1900’s,hardly usable due to its fragility.

However, optimisation of deacidification is a complextask, not only due to the variety of paper materials used,but also due to the fact that the degradation processes,i.e. oxidation, taking place in moderately alkalinepaper, were relatively rarely studied2 and not wellunderstood. Since cellulose oxidation is a slow process,the need for extremely sensitive analytical techniqueswas also evident. For these reasons, the consortium offive partners: University of Ljubljana, Faculty forChemistry and Chemical Technology, Slovenia;National and University Library, Slovenia; PolymerInstitute of the Slovak Academy of Sciences, Brati-slava, Slovakia; The Netherlands Institute for CulturalHeritage, Amsterdam, The Netherlands; and CentreNational d’Evaluation de Photoprotection, Aubiere,France, gathered with the goal to construct a newinstrument exploiting a rarely studied phenomenonobserved during oxidation of paper, i.e. chemi-luminescence, the weak light emitted by molecules as aresult of a chemical reaction. This innovative approach,combined with comprehensive studies ofthermooxidative and photooxidative degradation of

– Using the chemiluminometric approach and a varietyof other methods, details of the cellulose oxidation

Figure 2: The instrument consists of two parts, connected byfibre optics. The measuring chamber (left) serves to isolatethe sample from external light and to provide constantmeasuring conditions in the surrounds of the examined part.The light-sensing part (right) serves to translate light signalsto digital ones.


process were elucidated, such as the influence ofcarbonyl groups.4,5 It is thus recommendable to washany degradation products out of paper and to performa reduction pre-treatment of paper to be deacidified,if possible.

– Application of advanced kinetic calculations tochemiluminometric data lead to development ofdegradation software with which we can predict ratesof degradation at room temperature.6,7 These data areof extreme importance for the collection manager, asaccelerated degradation experiments performed inageing chambers are of little significance for ageingduring storage conditions. In future applications, suchprediction methods may allow the conservationscientist to evaluate a conservation treatment on anoriginal, as only a micro-sample is needed.8

– Using a newly invented analytical technique, it wasshown that the content of peroxides during oxidationof cellulose is extremely low9 – this led to theconclusion that antioxidants with the role of radicalscavengers might not be very effective forstabilisation of paper.

– Relative humidity was shown to have an extremelyimportant role during degradation of moderatelyalkaline paper – by correctly adjusting the relativehumidity level, an up to 10-times decreased rate ofdegradation was observed at the conditions of study.10

This research indicates an important future line ofstudy, which should lead to better guidelines for long-term storage conditions.

– A comprehensive set of experiments was performedat four temperatures of accelerated ageing, allowingus to extrapolate the ageing behaviour of a variety oftreated models and real historic papers to roomtemperature. Thus, we obtained the data on stabilityof differently treated papers (containing CaCO3,MgCO3, selected antioxidants) at the conditions ofuse.

– By comparison of natural light-ageing with threedifferent experimental techniques of artificial light-ageing, we produced guidelines for the conservationresearcher on how to conduct studies on photo-stability of paper. Our studies have shown an extremesensitivity of photo-aged papers towards lateroxidative ageing in darkness.11 This leads to theconclusion that for exhibited objects, the deacidifi-cation also has to be carefully selected: MgCO3 andhalides showed a stabilizing effect.

– Manual deacidification of paper using aqueoussolutions of Ca(HCO3)2, Mg(HCO3)2 and Ca(OH)2were carefully optimised regarding concentration ofthe alkali, time of immersion, the resulting pH andalkaline reserve.

– At the project completion, members of the project, incooperation with other renowned scientists from thefield, have set to write a book on paper degradation,summing up the recent advances.

– The Papylum webpage became an important resourceof information and literature data on paper

degradation. The database will continue to bedeveloped in the future: http://papylum.uni-lj.si

Research within the Papylum project thus lead toconstruction of a new valuable tool for the conservationresearcher, the most important result. Using the tool,and a variety of other optimised and even newlydeveloped methods, a profound understanding ofcellulose oxidation was gained. The extensiveexperimental plan using altogether more than 150different paper samples lead to data on rates ofdegradation at storage conditions and during irradiationwith daylight during exhibitions – on the basis of suchinformation, the collection manager is able to choosethe optimal treatment.The chemiluminometric approach has already led tofirst useful implementations outside the Papylumproject, e.g. studies of laser-treated paper12, 13 and ofcotton textiles.14 This demonstrates the validity of ourresearch directions.The project also points to topics important for futureresearch. On one hand, guidelines and risk assessmentfor storage conditions should be evaluated, especiallyregarding recommendations on relative humidity. Onthe other hand, lignin (not an object of our study) wasshown to exhibit strong chemiluminescence duringoxidation – the newly developed methodology couldthus help solving other acute problems in conservationand preservation of paper-based cultural heritage for thefuture. The developed chemiluminometric techniquedeserves to be explored further in the area of culturalheritage materials of organic origin, e.g. textiles,varnishes, synthetic polymers, etc.

3. AcknowledgementThe authors gratefully acknowledge the support of theEuropean Commission, Fifth Framework Programme,Key Action “City of tomorrow and cultural heritage”within the Energy, Environment and SustainableDevelopment, Contract n° EVK4-CT-2000-00038,project Papylum. The work is the sole responsibility ofthe authors and does not represent the opinion of theCommunity. The Community is not responsible for anyuse that might be made of the data appearing herein.

4. References1. A. Barański, K. Frankowicz, Z. Harnicki, Z. Koziński, T.

Łojewski, Acidic books in libraries. How to count them, Proc. 5th

European Conf. Cultural Heritage Research: a Pan-EuropeanChallenge, R. Kozłowski, Ed., Cracow, Poland, May 16–18th

2002, Polish Academy of Sciences, Cracow, 2003, pp. 283–285.2. J. Kolar, Mechanism of Autoxidative Degradation of Cellulose,

Restaurator 1997, 18, 163–176.3. http://www.lumipol.com, accessed 28/10/2004.4. M. Strlič, D. Kočar, J. Kolar, J. Rychlý, B. Pihlar, Degradation

of pullulans of narrow molecular weight distribution – the roleof aldehydes in the oxidation of polysaccharides, Carbohydr.Polym., 2003, 54, 221–228.

5. J. Malešič, J. Kolar, M. Strlič, Effect of pH and Carbonyls onthe Degradation of Alkaline Paper, Restaurator, 2002, 23, 145–153.


6. J. Rychly, M. Strlič, L. Matisová-Rychlá, J. Kolar,Chemiluminescence from paper. I. Kinetic analysis of thermaloxidation of cellulose, Polym. Degrad. Stab., 2002, 78, 357–356.

7. J. Rychlý, L. Matisová-Rychlá, M. Strlič, Kinetic Aspects ofChemiluminescence Response to Periodic Changes ofTemperature during Thermal Treatment of Cellulose, Polym.Int., 2000, 49, 981–986.

8. D. Kočar, J. L. Pedersoli, M. Strlič, J. Kolar, J. Rychlý, L.Matisová-Rychlá: Chemiluminescence from paper II. The effectof sample crystallinity, morphology and size, Polym. Degrad.Stab., 2004, 86, 269–274.

9. D. Kočar, M. Strlič, J. Kolar, B. Pihlar, A new method fordetermination of hydroperoxides in cellulose, Anal. Bioanal.Chem., 2002, 374, 1218–1222.

10. D. Kočar, M. Strlič, J. Kolar, J. Rychlý, L. Matisová-Rychlá, B.Pihlar, Chemiluminescence from paper III. The effect of

superoxide anion and water, Polym. Degrad. Stab., 2004,submitted.

11. J. Malešič, J. Kolar, M. Strlič, D. Kočar, D. Fromageot, J.Lemaire, O. Haillant, Photo-induced degradation of cellulose,Polym. Degrad. Stab., 2004, submitted.

12. P. Rudolph, F. J. Ligterink, J. L. Pedersoli Jr., M. van Bommel,J. Bos, H. A. Aziz, J. B. G. A. Havermans, H. Scholten, D.Schipper, W. Kautek, Characterization of laser-treated paper,Applied Physics A, 2004, 79, 181–186.

13. V. S. Šelih, M. Strlič, J. Kolar, D. Kočar, B. Pihlar, Lasercleaning of paper – a step towards optimisation, Durability ofpaper and writing, 16–20 November 2004, Ljubljana, Slovenia.

14. M. Strlič, J. Kolar, Degradation and stabilisation of cellulosicmaterials, Scientific Analysis of Ancient and Historic Textiles:Informing Preservation, Display and Interpretation, 13–15 July2004, Winchester, UK, 2004.


THE MASTER PROJECT: AN EARLY WARNING SENSOR FORENVIRONMENTAL DETERIORATION OF PAPER AND OTHERORGANIC MATERIALSN. Blades*1, E. Dahlin2, J. Henriksen2, T. Grøntoft2, S. Rentmeister3, M. Cassar1, J. Taylor1, M. Lazaridis4

and D. Howell5

1 Centre for Sustainable Heritage, University College London, London, UK2 Norwegian Institute for Air Research, Kjeller, Norway3 Albert-Ludwigs Universität Freiburg, Germany4 Technical University of Crete, Hania, Greece5 Historic Royal Palaces, London, UK


1. IntroductionThe MASTER project is researching the application ofnovel organic polymers as early warning sensors forenvironmental deterioration of Europe’s organic objectsin museums, galleries, historic houses, archives andlibraries. The intention is to develop a sensor that canindicate the rate of chemical change, or damage, thatobjects are likely to suffer in a particular storage ordisplay environment. The main processes of chemicaldeterioration for organic objects will involve eitheroxidation or acidic processes, or possibly a combinationof both. These processes may result from inherent vice,but, as is well known, are to a large degree caused byenvironmental factors such as moisture, pollutants, lightand UV radiation. Chemical deterioration is usuallyaccelerated by increased temperature and relativehumidity and many material deterioration processes arethe result of these parameters acting synergistically.The MASTER project is researching novel sensors thatcan capture these synergies to give a more direct earlywarning of the potential for damage to organiccollections, than is possible from parameter (i.e.pollutant concentration, temperature, relative humidity,light, etc) monitoring alone.

2. Sensor research and developmentAt present three different early warning systems arebeing investigated.

A novel polymer is being researched as a potential‘generic sensor’, i.e. a sensor that will respond to therange of environmental parameters implicated in thechemical deterioration of organic materials, as listedabove. Certain polymer films are known to deterioratechemically and photochemically due to environmentalstress and light. They do so at a rate that is appropriateto a sensor: measurable deterioration appears after afew weeks’ exposure in typical environments. This isalso sufficiently long to give a good estimate of thequality of the long-term environment objects areexposed to. The chemical deterioration of certainpolymers has been shown to be detectable by simple

techniques such as UV-visible spectrometry. Thegeneric sensor prototype is manufactured by spincoating the polymer onto a glass substrate. Its responseto different environmental factors is being calibrated inthe laboratory at Norwegian Institute for Air Researchin controlled exposure experiments, under differentregimes of pollutant concentrations, humidity and light.On exposure the generic sensor will give a singlenumber response that can be used as an early warningmeasure of the quality of an environment.

Two other sensors that can give more specificinformation about the quality of a storage or displayenvironment are also being researched. These aredesigned to respond selectively to oxidation and acidicdeterioration processes. Under development at theAlbert-Ludwigs Universität, Freiburg, these‘quantitative oxidising/acidity’ (QOA) sensors are alsopolymer based, but gain their specificity through theuse of dye systems that can respond to either oxidationor acidic processes. The dyes and polymer are dissolvedin a solvent and spin coated onto a glass substrate. Thespeed of the sensor response is controlled by the dyesystem and also the polymer used in the coating.Polymers with high gas permeability give a fasterresponse than those with low permeability. In this waya sensor technology originally developed foroccupational hygiene processes can be adapted to give aresponse within one month’s exposure in a typicalindoor cultural heritage environment. An oxidising dyesystem, based on the use of indigo and other pollutant-sensitive dyes is being tested in the laboratory and itsresponse is being calibrated. Measurement is by asimple UV-visible spectrometer method, as for thegeneric sensor. Work is still under way to find asuitable, stable acidic dye system.

3. End-use involvement with the researchA key aspect of the MASTER project has been theinvolvement of an End User Group, made up ofrepresentatives of European cultural heritageorganisations, who have a wide experience of caring for


cultural heritage collections, both at the strategic andpractical levels. They have given their input to theproject through two workshops where the proposedresearch was presented to them and they were required,collectively, to present a response from a practicalperspective, on what was needed to make a sensor thatthey would find useful in their own work in collectionscare. Whilst remaining within the original researchplan, the research has responded to the end userrequests. One of these requests was for a visible changesensor and research is under way to find suitableoxidation and acidity systems that undergo visiblecolour changes. So far only laboratory studies havebeen conducted, but promising dye and pH indicatorsystems have been identified and are being tested.

4. Field test programmeTwelve month field tests of the generic and QOAsensors are under way at ten cultural heritageinstitutions across Europe. At each test site there areexposures in the outdoor environment, indoor environ-ment and an enclosed environment, such as a displaycase or storage cupboard. In parallel, diffusion tubemeasurements are being made of the concentrations ofsulphur dioxide, nitrogen dioxide, ozone and organicacids; light, temperature and relative humidity are alsobeing measured. These data will be used to interpretand correlate the sensor response at the conclusion ofthe twelve-month field test programme. Also, samplesof standard paper and silk are being exposed at the

indoor and enclosed sites for the full twelve months ofthe field test in order to assess their deterioration incomparison with the sensor response and environmentalconditions. The silk will be analysed for polymermolecular weight distribution by size exclusionchromatography, a method developed by Historic RoyalPalaces; whilst degree of polymerisation (DP) ofcellulose in the exposed paper samples will bedetermined by viscometry at the University ofLjubljana.

5. Integration of the sensor into preventiveconservation strategy

As well as the technical research of the project, in orderto support the application and interpretation of thesensors, research is under way to determine how thesensor application can be incorporated into preventiveconservation strategy as an early warning device. Thisstrategy approach will link to existing work on forinstance the development of European conservationstandards, published studies of environmentaldeterioration of organic materials and current thinkingon risk assessment and value. The approach will bepragmatic, and will take into consideration the differentpriorities, resourcing and buildings of the diverseinstitutions that care for organic objects in Europe. Itwill give information on how to interpret sensorresponses and the steps that should be followed in usingthe sensor and the subsequent actions that may need tobe taken.


A LIGHT DOSIMETER FOR MONITORING CULTURAL HERITAGE:DEVELOPMENT, TESTING AND TRANFERS TO MARKET (THE LIDO-PROJECT)A.-L. Dupont*1, H. Römich2, G. Martin3, M. Bacci4, B. Lavedrine5, C. Cucci6

1 CRCDG Paris, France2 Fraunhofer ISC, Wertheim, Germany3 V&A, London, UK4 IFAC, Florence, Italy5 CRCDG Paris, France6 IFAC, Florence, Italy

* [email protected]

1. BackgroundExposure to artificial or natural light may damagevaluable heritage objects, by causing discoloration,fading, or brittleness of the historic material. Ratherthan limiting the time of exposure for each object, it isadvisable to monitor the lighting conditions, e.g. byusing a data logger. However, a continuous monitoringprogram would be rather expensive and applicable onlyfor selected examples. An obvious attempt to avoidcomplicated measurements is to use a sacrificialsimulation material on which the effect of light can bestudied. For this purpose, the only system available onthe market has been the Blue Wood Standard (BWS),developed for the industrial sector. Its application inmuseums was limited because of the low sensitivity tomuseum lighting conditions.

2. Objectives of the LiDo-projectThe LiDo project (EVK4-CT2000-00016) wasconceived in response to the need for a more sensitiveand standardised dosimeter, which should be easy tohandle, environmentally robust, inexpensive, cumulati-ve and designed for wide use in the heritage sector. Thefirst step in the work program was concerned with theinvestigation of different combinations of dyes/matrices/substrates and their response to different lightlevels by laboratory experiments. The field exposurewas carried out in selected museums in London, Paris,Berlin, Florence and Prague. The final step of theproject was dedicated to the development of astandardised preparation method and quality control forlight dosimeters, which will be marketed under thename ”LightCheck®”.

3. AchievementsAs a final result of the project two types of lightdosimeters are available, based on the same principle: alight sensitive coating on a substrate changes colourduring exposure to light. A calibration has beenestablished between the colour and the luminousexposure. The luminous exposure given in the colourreference scale corresponds to the potential damage of

the lighting conditions on site. Both types of dosimetersare more sensitive than BWS, covering acomplementary range of application: LightCheckâ Ultra”LCU” is designed to monitor the exhibition of verylight sensitive objects (and short exposure times),whereas LightCheckâ Sensitive ”LCS” is applicable forthe more durable objects (and longer exposure times).

LightCheckâ is introduced as a new early warningsystem for preventive conservation, which permits toevaluate the quantity of light received by an artefactduring exhibition. This will allow a better control ofenvironmental conditions and will provide a new toolfor the survey of guidelines and standards inconservation.

The goal set up for the project has been reached: newlight dosimeters have been developed, tested in thelaboratory under controlled conditions and in fieldexposures. At the end of the project a marketingstrategy will ensure a commercial distribution of theproduct and thus the transfer to market.

The achievements of the project were presented to abroad audience during a public workshop in Florence(27/28 Nov. 2003). The web page for the LiDo projectat www.lido.fhg.de provides links to actual publicationsand on how to order LightCheckâ (see also:www.lightcheck.co.uk). The research within LiDo wasawarded with the ”Pan-European Grand Prix forInnovation” in Monaco, on 6th December 2003.

4. References1. M. Bacci, C. Cucci, A.-L. Dupont, B. Lavédrine, M. Picollo, S.

Procinai, Disposable indicators for monitoring lightingconditions in museums, Environmental Science and Technology,2003, 37, 687–56.

2. H. Römich, G. Martin, LiDo: a light dosimeter for monitoringcultural heritage, V&A Conservation Journal, 2003, 43, 2–3.

3. H. Römich, G. Martin, B. Lavédrine, M. Bacci, LightCheck – anew tool in preventive conservation, V&A Conservation Journal2004, 47, 17–18.

4. S. Gerlach, H. Römich, M. Picollo, C. Cucci, B. Lavédrine, G.Martin, M. Dvorak, Proc. Of the conference ”Methods andbenefits of environmental testing and engineering”, organised byConfederation of the Europ. Environmental Eng. Soc. (CEEES),Conference, 14th and 15th May 2003, Nuernberg, Germany, 2003,1–10.


HYPERSPECTRAL IMAGING – CONCEPTS AND POTENTIAL INPAPER AND WRITING DURABILITY RESEARCHJ. H. Scholten*1, M. E. Klein1, Th. A. G. Steemers2

1 Art Innovation BV, Oldenzaal, The Netherlands2 Nationaal Archief, Den Haag, The Netherlands


1. IntroductionNon-destructive optical techniques have alwaysbelonged to the most important investigation methodsapplied in paper and writing durability research. Visualinspection of a document is a fast and inexpensive wayof detecting critical areas, where e.g. ink corrosionoccurs in an advanced state, or where discolouration orstaining jeopardizes the legibility. From visualinspection alone, the experienced researcher can get aqualitative impression of the general condition of theinspected material.

However, for comparing the state of conservation ofdocuments with each other without actually having toview them simultaneously, quantitative analyticalmethods are required. Besides a number of othersophisticated spectroscopic techniques, opticalreflectance spectroscopy and colour measurement, hasbeen used successfully for analysing local materialproperties in relation e.g. to paper degradation.

Unfortunately, practically all of the quantitative opticaltechniques are per se non-imaging, i.e. that eachmeasurement represents the average properties onlyaround a single point on the document. Due to thelimited measuring speed, scanning the document toobtain an adequate spatial resolution is usually totallyimpractical, so that these quantitative methods involvesome major problems inherent to non-imagingtechniques. For example, identifying representativedocument areas with a sufficiently homogenousresponse in the first place, and re-addressing exactly thesame small area reliably in subsequent measurements isoften a huge challenge.

An advanced multi-spectral digital imaging system,such as the ARTIST camera1, gathers opticalinformation from a significant document area with ahigh spatial resolution, and can thus overcome theproblems typical for single-point techniques. However,at present such imaging systems are almost exclusivelyused in a non-quantitative way, and even when usedquantitatively, their comparatively small number ofwavelength bands (about 5–10) is totally insufficientfor analytical reflectance spectroscopy.

We are currently developing an instrument for trulynon-destructive paper and writing durability research,which combines the high spatial resolution of a digitalcamera with the large number of wavelength bandsrequired for high-resolution spectral reflectance and

accurate colour measurements. The instrument is to beused for application studies aiming at a reliableidentification of different types of ink, early-detectionof ink corrosion, and an objective quantification of theresulting degree of document degradation.

In this contribution, we discuss the operating principleof this so-called hyperspectral imaging system and wepresent initial experimental results obtained with alaboratory setup, which already indicate the hugepotential of this novel technique.

2. The operation principle of hyperspectralimaging

The term hyperspectral imaging (HSI) refers to theacquisition of a series of digital images at a largenumber (50–100) of different, well-defined opticalwavelengths in the ultra-violet, visible and near-infrared. HSI results in the simultaneous, precisedetermination of the reflectance spectra from all areasof a document with a high spatial resolution. Thereflectance spectra often show significant differencesfor different types of ink (or other substances), whichmay look identical in direct viewing or conventionalRGB imaging. Using dedicated software, the spectralproperties can be exploited for distinguishing inks orareas exhibiting different degrees of paper degradation,as well as for automatic mapping of their distribution,e.g. in form of false-colour images.

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Among several possible concepts for realizing ahyperspectral imaging system, we have chosen thesetup shown schematically in Fig. 1. The documentunder investigation is placed in a light-proof cabinetand illuminated from two sides under an angle of 45şwith two identical light sources emittingmonochromatic light (spectral bandwidth 10–20 nm).The center wavelength emitted by these light sourcescan be tuned in steps of 10 to 20 nm over the entirewavelength range from 380 to 1100 nm. The advantageof this instrument configuration is that the stress to thedocument is absolutely minimal, as the light intensity ismuch lower than in conventional setups and contains noharmful UV and heat radiation.

A high-resolution monochrome CCD camera takes ateach wavelength an image of the document. The tuningof the light sources and the image acquisition of theCCD camera is controlled and synchronized by acomputer. Dedicated software converts the raw imagedata into calibrated reflectance images, resulting in acomplete spectral reflectance curve for each imagepixel, corresponding to a resolution of 300 dpi andmore. The spectral data in the visible range can be usede.g. for calculating CIE colour values.

In the planned research, the calibrated reflectanceimages will then be analysed for spectral signatures,which can be related e.g. to different types of inks, inkcorrosion, or other types of paper degradation.

3. Initial experimental investigationsFor initial experiments, we built a laboratoryhyperspectral imaging setup, where a document area ofabout A8 size was illuminated with a wavelengthtunable light source (bandwidth <15 nm). A modifiedversion of our ARTIST camera was used to image thedocument area at each wavelength.

In order to investigate differences in the spectralreflectance curves of different types of inks, weoverlapped two manuscripts in the field-of-view of thecamera and imaged them at 57 different wavelengths inthe range of 540 to 1100 nm (step width 10 nm).

From the calibrated reflectance images shown in Fig. 2,it can be seen that the writings in both documents havea high contrast at 570 nm, however, at longerwavelength the contrast in the lower document isconsiderably reduced while the writing in the upperdocument virtually disappears at 1000 nm.

For a quantitative spectral analysis, we extracted fromthe hyperspectral image series the spectral reflectancecurves at 4 small ink areas (size ~0.3 mm2) in eachdocument.

Figure 2: Calibrated relfectance images for wavelengths 570nm, 840 nm, 1000 nm, and false colour image generated byratioing the reflectance images at 840 nm and 570 nm. Blue:ratio ł4; red: 4 > ratio >1; gray: ratio >1.

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As shown in Fig. 3, the spectral reflectance curves ofthese 8 regions of interest (ROI) clearly fall into twogroups. ROIs 1–4 in the upper document exhibit verylow reflectance values at short wavelengths, and a steepincrease at >700 nm. As compared to this ROIs 5–8from the lower document feature somewhat higherreflectance valuess at short wavelength, and a moregradual increase towards longer wavelengths.

These spectral signatures of the two writings wereexploited for mapping their distributions in the falsecolour image shown in Fig. 2. This was generated bycalculating for each pixel the ratio of the spectralreflectance values at 840 and 570 nm, and choosingblue colour to indicate ratio values ł4, red for ratiovalues <4 but >1, and gray tones for ratio values <1. Byapplying this very simple algorithm, the resulting false-colour image shows the writing in the upper documentmainly as blue pixels, and in the lower document onlyas red pixels.

4. Summary and conclusionIn summary, we discussed the design of a hyperspectralimaging instrument dedicated to research in paper andwriting durability. Initial experimental results obtained

Figure 3: Spectral reflectance curves of ink areas in theupper manuscript (ROIs 1–4) and int the lower manuscript(ROIs 5–8) shown in Fig. 2. The differences in the curvescan be exploited for distinguishing between the differentwritings.


with a laboratory setup show that such an instrumentcan be used successfully for distinguishing betweendifferent types of inks.

In conclusion, our investigations indicate that thehyperspectral imaging instrument has a huge potentialto become a standard research tool for a fast, non-destructive, spatially resolved analysis of historic

documents, e.g. for assessing their condition orenhancing their legibility.

5. References1. J. B. G. A. Havermans, H. Abdul Aziz, H. Scholten, Non

destructive detection of iron-gall inks by means of multispectralimaging. Part 2: Application on original objects affected withiron-gall-ink corrosion, Restaurator, 2003, 24, 88–94.


THE USE OF X-RAY DIFFRACTION TO ASSESS CRYSTALLINITY INHISTORICAL PAPERCraig J. Kennedy, Tim J. Wess*Cardiff University, Cardiff, Wales, United Kingdom


For nearly 2,000 years the primary methods of paper-making have ensured that paper is a material composedprimarily of the fibrous polysaccharide cellulose.Native crystalline cellulose is comprised of chainsarranged in parallel with a two-fold screw symmetryalong the chains due to the β-[1,4] linkage of the D-glucose subunits. Two phases coexist within nativecellulose type I, Iα and Iβ1.

The degradation of cellulose in paper may be a functionof processes such as acid hydrolysis, or of a free-radicalmediated oxidative process. In both cases, scission ofthe cellulose polymers is evident. Factors such as thepresence of inks, temperature, pH, humidity and theapplication of cleaning techniques may be implicated inaccelerating cellulose degradation.

The precise method of historical degradation ofcellulose is unclear. Recent studies have indicated thatamorphous regions of cellulose may be moresusceptible to damage than crystalline regions2.

X-ray diffraction is a tool that can be used non-destructively, i.e. without the requirement for drilling orcutting samples in to small sections for analysis. In thismanner, valuable documents may be assessed andreturned to their collections without apparent damage.A number of features of the cellulose within paper canbe analysed by X-ray diffraction, including the degreeof crystallinity, crystal size and orientation. Presentedhere is preliminary analysis of X-ray diffraction profiles(fig. 1) from historical papers (circa. 19th century),which is compared with modern paper and celery,which is rich in type I cellulose from the cell walls.

X-ray diffraction analysis was conducted at beamline14.1 at the Daresbury Synchrotron Radiation Source,England, UK. Samples were exposed to the synchrotronbeam for 10 seconds per image. The X-ray wavelengthwas 0.1488 nm, and the sample-to-detector distancewas 30 mm. This allowed for clear observation of themain diffraction peaks from paper.

2-dimensional X-ray diffraction images were convertedto 1-dimensional linear intensity profiles using in-housesoftware. Figure 2 shows a linear profile from one ofthe historical papers.

Crystallinity in samples is difficult to determine as anabsolute value as assumptions need to be maderegarding the shape of an amorphous contribution to thediffraction profile. However, a relative crystallinityvalue (Xc) to compare samples can be made from:Xc = I200/ITOT

where I200 is the integrated intensity derived from aLorentzian peak fit of the (200) reflection, and ITOT isthe total intensity at that position; i.e. the sum of thepeak intensity and amorphous background3. Peak fittingwas carried out using the program Xfit (CollaborativeComputing Project 13 (CCP13)). Such Xc values allowfor a rapid qualitative comparison of different samples.

Table 1 displays Xc values for historical papers andreference samples. Paper 1 showed an area clearlydamaged by the ingress of water; X-ray diffractionimages were taken from both intact and damaged areasof that sample. Paper 2 is a historical newspaper with

Figure 1: An X-ray diffraction image of historical paper 1,taken at beamline 14.1 at the Daresbury synchrotron. The(200), (002) and (004) reflections are indicated.

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Figure 2: A linear intensity profile from an X-ray diffractionpattern of historical paper 1. Labelled is the (200) reflection,which is used to measure crystallinity in cellulose samples,and the (004) reflection.


ink writing on the surface; diffraction images weretaken from the inked and non-inked regions forcomparison.

Table 1: Crystallinity values (Xc) of historical paper andreference samples. Mean values are presented, ± 0.04.

Sample Xc

Historical Paper 1 0.513Historical Paper 1 – Damaged area 0.383Historical Paper 2 0.412Historical Paper 2 Inked region 0.443Historical Paper 3 0.322Historical Paper 4 0.394Modern Paper 0.518Celery (Cell Wall) 0.401

Of the historical samples presented here, papers 1 and 2have relatively high Xc values compared to papers 3and 4. Historical paper 1 displays an Xc value similar tothat of modern paper. Of interest here is the effect ofwater damage and ink on the cellulose crystallinity. Thewater damaged paper displays a much lowercrystallinity value than the undamaged area of the samesample, indicating that the crystalline regions haveundergone damage. The sample with ink on the surface,however, displays a slight increase in Xc values,indicating that the presence of ink has the effect ofincreasing the relative crystallinity of the sample,possibly by degrading the amorphous regions ofcellulose preferentially. This indicates that the method

of cellulose degradation is varies with differing externaleffects. Further examination of this phenomenon mayprovide a clearer understanding of the mechanisms ofcellulose degradation in paper.

This analysis provides an indication of the potential forthe use of X-ray diffraction to analyse historical paperdocuments. This technique may be expanded, asmicrofocus X-rays, with beamsizes as small as 2ěm,can allow for surface-to-surface scans of paperdocuments to analyse the effects of surface treatmentsand ink on the structure of cellulose throughout papercross-sections.

AcknowledgementsThanks to the staff at beamline 14.1 at Daresbury, fortechnical assistance and advice. We are grateful toHildegard Homburger, Berlin, for providing the papersamples.

References1. Atalla R. H., VanderHart D. L., Native cellulose: a composite of

two distinct crystalline forms, Science, 1984, 223, 283–285.2. De Souza Lima M. M., Borsali R., Rodlike cellulose

microcrystals: structure, properties and applications, Macromol.Rapid Comm., 2004, 25, 771–787.

3. Burghammer M., Müller M., Riekel C., X-ray synchrotronradiation microdiffraction on fibrous biopolymers like celluloseand in particular spider silks. Recent Res. Devel. Macromol.,2003, 7, 103–125.


ESTIMATION OF THE PROGRESS OF OXIDATIVE DEGRADATION OFPAPER USING CHEMILUMINOMETRY AND STANDARD DOUBLE-FOLD TESTJozef Hanus*1, Jozef Rychlý2, Jarmila Mináriková1, Lyda Matisová-Rychlá2, Svetozár Katuščák3, MilanVrška3, Vladimír Bukovský4

1 Slovak National Archives, Bratislava, Slovak Republic2 Polymer Institute, Slovak Academy of Sciences, Bratislava, Slovak Republic3 Faculty of Chemical and Food Technology, Slovak University of Technology, Bratislava, Slovak Republic4 Slovak National Library, Martin, Slovak Republic


Degradation of cellulose and loss of its use properties iscaused by two main processes, particularly by acid-catalyzed hydrolysis and oxidation. The first reaction isdirect cleavage of 1,4 β-glycosidic bond which takesplace after its interaction with hydrogen ions and leadsto semiacetal chain-end groups. On the other hand,oxidation by oxygen is much more complex processoccurring via oxidation of hydroxyl groups on gluco-pyranosyl structural units into carbonyl and carboxylgroups. The latter facilitates scission of the cellulosebackbone as well. Both, production of chain-endsemiacetal groups and oxidation of hydroxyl groups areaccompanied by weak light emission (chemi-luminescence). The light emission may be releasedfrom several reaction steps involving peroxyl freeradicals recombination. Peroxyl radicals are formed inthe decomposition of hydroperoxides and the process oftheir termination is usually accompanied by the mainchain scissions. Somewhat complicating factor ischemiluminescence from hydrogen peroxide in alkalinemedium where singlet oxygen is the product of self-termination of two hydrogen peroxyl radicals. Itappears, therefore, that chemiluminescence may berelated to the process of chain scissions and thechemiluminometric method may serve as an importantcomplementary method in studies of cellulosedegradation. Such a case was shown for degradation ofpure cellulose (Whatman filter paper)1, however, morecomplex real paper systems containing differentadditives including lignin, still remain the subject offurther studies.

In the present paper we describe chemiluminometricexperiments in isothermal conditions (at constanttemperature) and in dynamic conditions (using varioustemperature gradients), for several papers: newsprint,bank and writing paper with and without deacidificationtreatment, and additionally aged from 0 to 24 days at105 °C. The rate constants estimated from dynamicchemiluminometric experiments for 105°C arecompared with a series of standard tests on remaininguse properties of the aged paper samples.

Using the example of a bank paper (Figures 1a and 1b)we see a correlation between the number of doublefolds and relative polymerization degree obtained from

transformation of chemiluminescence intensity I vs.temperature T experimental curves in oxygenatmosphere, using the equation:

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where Φ is proportionality constant, β is the rate ofheating, DP is the degree of polymerization and t istime. The experimental runs for original (a) anddeacidified (b) bank papers were attempted. Theproportionality constants Φβ were calculated from non-isothermal analysis of the chemiluminescence intensityvs. temperature experimental curves, i.e. from the totalsurface below the determined curve1. For thedetermination of the relative degree of polymerization,the temperature 90 °C was chosen arbitrarily but anyother temperature below 120 °C gives the similar shapeof plot. The correlation also exists between the rateconstant of sample degradation found e.g. for 105 °Cand the number of double folds in machine direction.The observed correlations are promising and might leadto a more intensive use of the chemiluminometrictechnique for estimation of paper stability.

Correlation between the number of double folds for thesample of bank paper and its relative degree ofpolymerization determined from the surface below thechemiluminescence intensity – temperature runs inoxygen atmosphere at 90 °C and the rate constant ofsample degradation at 105 °C are presented in Figures 1and 2. The samples of original acidic (a) anddeacidified (b) bank paper were artificially aged in airby dry heat at 105 °C according to ISO 5630/1 forperiods of 3, 6, 12 and 24 days. The numbers in theplots denote days of accelerated ageing.

AcknowledgmentsThe authors gratefully acknowledge the support of theEuropean Community, 5th Framework Energy,Environment and Sustainable Developmentprogramme, contract no. EVK4-CT-2000-00038(PAPYLUM). The work is the sole responsibility of theauthors and does not represent the opinion of the


Community. The Community is not responsible for anyuse that might be made of the data appearing herein.

The authors also acknowledge the support of the ProjectKNIHA.SK granted by the Ministry of Education of theSlovak Republic.

Figure 1: Number of double folds (machine direction) forbank paper vs relative degree of polymerization determinedfrom the surface below the chemiluminescence intensity –temperature runs in oxygen atmosphere at 90 °C.

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References1. J. Rychlý, M. Strlič, L. Matisová-Rychlá, J. Kolar,

Chemiluminescence from paper. 1. Kinetic analysis of thermaloxidation of cellulose, Polym. Degrad. Stab. 78, 357-367, 2002.


OXIDATIVE AND HYDROLYTIC PATH OF PAPER DEGRADATIONSTUDIED BY IN-SITU FTIR TRANSMISSION SPECTROSCOPYJ. Łojewska*1, P. Miśkowiec1, L.M. Proniewicz1,2

1 Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland2 Regional Laboratory of Physicochemical Analysis and Structural Research, Ingardena 3, 30-060 Kraków, Poland


2. ExperimentalFor the kinetic studies, we used model paper (P1)samples: bleached sulphite softwood cellulose paperwith 99.5 wt % cellulose content (grammage: 78 g/m2,BET: 1.21 m2/g) obtained from the Netherlands8. Inorder to collect transmission spectra thin paper plateswere prepared from P1.

The spectra were recorded by a FTIR spectrometer(Brucker Equinox 55) with a MCT detector at anoptical resolution of 2 cm-1 and 2 level zero-filling. Forthe accelerated ageing tests the quartz reaction chamberwith ZnSe optic windows was placed in the samplecompartment of the spectrometer. The chamber wasequipped with an electric furnace enabling heating inthe broad temperature range (to 900oC) and with a gassupplying and evacuating system.

3. ResultsBenefiting from the above mentioned advantagesoffered by the in situ experimental setup we haveproposed methods of paper spectra standardisation:

1. Spectra normalisation using an internal standarddefined as an integral absorbance of the CH 1900cm-1 band in the range 3000-2800 cm-1, and denotedas standard absorbance;

2. Removal of water molecular vibrations fromcarbonyl vibration region by preliminary desorptionof H2O from samples and by recording the spectra atelevated temperatures;

3. Introduction of the oxidation index, defined as a ratioof integrals of bands at 1730 cm-1 to that at1620 cm-1.

1. MotivationsMillions of books worldwide are menaced by paperdisintegration due to malignant and inevitabledegradation of cellulose chains caused by acid catalysedhydrolysis of glycosidic bonds. In order to prevent thisprocess mass deacidification programmes have beenlaunched. These now go hand in hand with researchwhich should deepen our understanding of the observedphenomena.

According to the most recent findings, cellulosedegradation should be regarded in terms of oxidativeand hydrolytic mechanisms1-3 where the two reactionpaths are autocatalytically accelerated by active oxygenspecies and protons, respectively. Notwithstanding,paper degradation kinetics is still based on formal ratelaws4,5 which are with better or worse results, used togenerate kinetic curves representing accelerated ageingof cellulose.

Typically, paper degradation progress is traced bymechanical or physical properties of paper such astensile strength, fold endurance1,6, dynamic modulus ormechanical loss tangent7. However, these propertiesprovide only macroscopic information. Anotherimplemented parameter has been the degree ofpolymerisation representing an average polymerisationstate of cellulose chains. Even though of paramount andpractical importance, these parameters do not give areal insight into molecular behaviour during thedegradation process. By contrast, highly sensitive tostructural changes in materials, vibrational spectroscopyseems still to have an unexploited potential inmodelling of kinetics of cellulose degradation, in spiteof copious amount of published material.

The goal of this work is a verification of oxidative andhydrolytic paths in cellulose degradation mechanism tofinally combine them in a formalism of mixed-controlled kinetic model5. In particular, it concentratesupon refining an in situ FTIR transmission technique tostudy accelerated ageing of paper materials. The mostessential advantage it has over other IR techniques isthat the technique provides information from the samesample area and allows us to observe real time chemicalchanges in material under controlled conditions. Due tothe spectral complexity our focus in this work has beenthe 1400-1800 cm-1 region where CO groups ofdifferent degrees of freedom occur. However, there arecontroversies in the literature concerning bandassignment even in such a limited range.

Figure 1: Isothermal oxidation of model paper (P1) samplein the dry air atmosphere at 150 oC monitored every 10 h byin situ FTIR measurements.


Complementarily, to remove water vibrations from theCO spectrum region, isotope exchange was applied andoptimised. The applicability of this method for ageingexperiments is, however, limited, because the propertiesof D-exchanged samples are different from originalprotonated samples.

The boundary conditions of experiments selected by usproved to be able to discriminate between hydrolysis ofglycosidic bond and oxidation of carbon atoms inglycopyranose anomers. Accordingly, under theconditions of various gas mixtures (dry air, watervapour, humid air) two types of experiments wereperformed: (i) short ageing tests at three selectedtemperatures (100, 150, 250 oC) and (ii) longerisothermal tests. Following the changes in spectra in thecarbonyl range as they increased with oxidation time(an example in Figure 1), various intermediates ofcellulose oxidation were distinguished starting from theleast oxidised monocarbonyl groups, through diketonesto aldehydes and carboxyles.

The band assignment was supported by the spectrafitting by mixed Lorentzian-Gaussian functionoptimization and literature data. The changes in bandintensities during paper oxidation were found tocorrespond to a parallel-consecutive mechanism. In thefirst approach a simple model taking into account bothband positions, and presumed reaction mechanism, isproposed and is schematically presented in Figure 2.

The assumptions were verified by independentexperiments. The position of -COOH stretching modeat 1730 cm-1 was confirmed by the experiment utilizingthe acidic groups neutralization with a dilute KOHsolution (Figure 3). As a result of the reaction withKOH, the intensity of vibrations at 1730 cm-1 weakened(curve b). At the same time the sub-bands coming fromother intermediate products of cellulose oxidationrevealed.

Figure 2: Consecutive-parallel mechanism of partialoxidation of cellulose, where intermediate products arerepresented by functional groups included in monomers andassociated with frequencies of their vibrations.

4. References1. M. Strlič, J. Kolar, 5th EC Conf. ‘Cultural Herit. Res.: Pan-Eur.

Challenge’, Cracow, Poland, 2002, 79-86.2. S. Margutti, G. Conio, P. Calvini, E. Pedemonte, Restaurator,

2001, 22, 67-83.3. M. C. Sistach, N. Ferrer, M. T. Romeo, Restaurator , 1998, 173-

186.4. X. Zou, T. Uesaka, N. Gurnagul, Cellulose, 1996, 3, 243-267.5. A. Barański, Restaurator 2002, 23, 77-88.6. K. L. Kato, R. E. Cameron, J. Appl. Polym. Sci., 1999, 74, 1465-

1477.7. S. Yano, H. Hatakeyama, T. Hatakeyama, J. Appl. Polym. Sci.,

1976, 20, 3221-3231.8. J. Havermans, Restaurator, 1995, 16, 209-233.

Figure 3: Model paper (P1) sample: a) aged for 110 h in dryair at 150 oC , b) then neutralised with 5×10-2 mol/dm3 KOHsolution and washed with distilled water.


DETERMINATION OF pH OF PAPERDrago Kočar*1, Matija Strlič1, Jana Kolar2, Boris Pihlar1

1 University of Ljubljana, Faculty of Chemistry and Chemical Tehnology, Aškerčeva 5, SI-1000 Ljubljana, Slovenia2 National and University Library, Turjaška 1, SI-1000 Ljubljana, Slovenia* corresponding author: [email protected]

1. IntroductionOf all paper properties, acidity/alkalinity is probably thecrucial parameter for stability of its most importantstructural element, cellulose1. Considering the role ofthis parameter also in permanent paper standards, itsproper determination is of primary importance. Severalprocedures for determination of paper pH have beenevaluated, ranging from standard extraction procedures,surface pH, “micro” pH determination, and use ofcoloured acid/base indicators, on 55 different samples.This work is published as a full paper elsewhere.2

2. Materials and methods

Paper samples

Papers and pulps of various origins were used and thetype of fibres was determined according to SCAN-G3:90 and SCAN-G4:90 standards. From books, onlypaper parts without print were used. Deacidifiedsamples were prepared by immersion in solutions of0.04 mol L-1 Mg(HCO3)2 or 0.01 mol L-1 Ca(HCO3)2.All samples were equilibrated at room conditions priorto use.

Determination of pH

The following procedures were used:

– Tappi 509 om-02 (cold extraction, 1 g of sample per70 mL of water, 1 h);

– Tappi 529 om-88 (pH of paper surface using a flatcombined glass electrode);

– Determination of pH using colour acid/baseindicators-containing pen (pHydrion, Talas, NewYork, USA);

– Determination of equilibrium pH: to 1.00 ± 0.01 gsample, 70 mL MilliQ water was added. The samplewas stirred at 250 r.p.m. and pH was followedcontinuously until an equilibrium (up to three days)was achieved.

– New method: to 0.070 ± 0.005 g sample in a reactiontube, 5 mL MilliQ water is added, previously aeratedfor 30 min in order to obtain a CO2-saturated solution(for samples with pH > 7). Samples are defibrillatedin a reaction tube using a precision hand drill with astand at 25,000 r.p.m. for 15 min.

– “Micro” determination of pH: samples are cut outwith a sharpened surgical needle of inner diameter0.8 mm. The average weight of such samplesdepended on the grammage of a particular paper, butwas approximately 10 µg. Aerated water was added(2 µL) and the pH was determined once the reading

stabilised (after max. 5 min) using the MI-415-2cmmicro combined glass electrode (MicroelectrodesInc., Bedford, USA).

3. Results and discussionWater in paper, if present in sufficient quantities, maycontain dissolved matter, some of which in ionic state.While, at present, the concentration of H3O

+ ions in thismatrix cannot be measured, the compounds can beextracted and the pH of extract determined. It isevident, though, that pH in paper will be affected by itswater content.

Determination of pH is relatively straightforward ifpaper samples are acidic. For such samples, allextraction procedures will give data in good agreementwith the standard cold extraction procedure.

Irrespective of the fact that the true pH in cellulosicfibres is difficult to determine, it seems that CO2 shouldbe taken into account when determining pH of alkalinepaper, since the material is usually in equilibrium withthe atmosphere in which it is stored and this regularlycontains CO2. None of the present standard procedurestake this into account.

A comparison between the equilibrium values and thevalues obtained with the standard extraction method(Fig. 1) shows that the standard method gives values upto 1 pH unit too low for gelatine surface sized samplesand values up to 2 pH units too high for samplescontaining MgCO3. The agreement between the twomethods is excellent only for acidic samples.

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Figure 1: A comparison of the determinations of equilibriumpH values with those obtained with the standard procedure.Only acidic samples are included in the correlation.


With the new procedure, a remarkable correlation withthe determinations using the method of determinationof equilibrium pH is evident (Fig. 2), in whichdispersions of paper samples are given ample time toequilibrate with the atmosphere. In the correlation, allsamples are included, even the surface-sized, althoughthese samples are not homogeneous.

If samples are alkaline, the following can be concluded:

– If the duration of extraction is short or if the mixing isnot adequate, the slow dissolution of alkali-earthmetal carbonates and the slow absorption ofatmospheric CO2 will not allow for properequilibrium to be achieved. Determinations of pH ofsuch alkaline extracts using the standard extractionmethods will lead to pH values which may be up to1.5 pH units too high. The repeatability isnevertheless below 0.15 pH units, yet sampleconsumption is high: 1 g is needed.

– With the surface method, the repeatability is lower,up to 0.30 pH units, yet this may also reflect sampleinhomogeneity. The time of dissolution and theamount of water are sufficient for rapid dissolution ofan equilibrium amount of CaCO3, meaning that thepH of such samples determined by the surfacemethod will not correlate with the measurementsobtained by the standard cold extraction procedure.Determination of surface pH cannot be considered asa non-destructive method, due to marks left at theedge of the wetted part of paper, along which paperdegradation proceeds faster. Gelatine used as surfacesizing leads to lower surface pH of papers than thebulk pH by up to a few units. This may beproblematic if the decision on whether to deacidify or

not is based on such information.– If using the standard cold extraction procedure, the

time to achieve equilibrium is excessively longespecially in the case of MgCO3-containing papersyet it can be shortened to 15 min if intensive mixingis used. Having optimised the type of mixing and thesample to water ratio, we propose a new procedure.Using this new procedure, pH of CaCO3-containingpulps was determined to be approx. 8.5, and the pHof MgCO3-containing pulps approx. 9.5. In paper, thetype and amount of additives may influence thesevalues considerably. Repeatability of determinationsusing the proposed procedure is lower than 0.12 pHunits, the amount of sample needed is 0.07 g. A rapidequilibration (15 min) with atmospheric CO2 can beachieved, which makes this method suitable forroutine determination of paper pH.

– Miniaturisation of the procedure using micro-combined pH electrodes leads to a satisfactorycorrelation with the proposed method, yet with lowerrepeatability: values of 1.0 pH unit are acceptable.The amount of sample needed for such determinationis low (circular cut of diameter <1 mm), yet severalsamples are needed to obtain a satisfactory averagevalue.

– Determination of pH using pH pens may providerough estimations, with errors up to several pH units.Caution should be taken especially if degraded,intensively yellow papers are under observation, ascolour evaluation is then difficult. This may beproblematic if the decision on whether to deacidify ornot is based on such information.

– Due to the slow dissolution of alkali-earth metalcarbonates, changes in relative atmospheric humidityand the resulting changes of water content in paperlead to fluctuations in local pH in paper. This shouldbe taken into account in paper stability studies, ifexperiments with dynamic humidity (humiditycycling accelerated ageing) are performed.

4. AcknowledgementsMinistry of Education, Science and Sports of theRepublic of Slovenia is gratefully acknowledged forsupporting this research (Programme P1-0153, projectL1-5237).

5. Reference1. L. F. McBurney, Degradation of Cellulose. 1. Kinetics of

degradation reactions, in: E. Ott, H. M. Spurlin, M. W. Grafflin(Eds.), Cellulose and cellulose derivatives, Vol. I, Interscience,New York, 1954.

2. M. Strlič, J. Kolar, D. Kočar, T. Drnovšek, V. S. Šelih, R. Susič,B. Pihlar, What is the pH of alkaline paper?, e-PS, 2004, 1, 35-47. Available on-line: www.e-preservationscience.org.

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Figure 2: A comparison of pH values of paper extractsobtained by the new method (N = 5) and the determinationsof equilibrium pH. All samples included in the correlation.


CHARACTERIZATION OF PAPER BY NEAR INFRAREDSPECTROSCOPYDirk Lichtblau, Manfred AndersZFB Zentrum für Bucherhaltung, Leipzig, Germany

[email protected]

coresponding author: [email protected]

Conservation and preservation decisions take intoaccount some general strategic guidelines and are basedon condition of the collection in question. Thecondition can generally be defined by physical,(micro)biological and chemical state of paperpreservation. Since chemical damage is usually notvisually detectable, it thus represents an especiallydifficult and critical parameter contributing to well-informed collection management. Since most classicaland widely available methods of analysis are either tooexpensive, too time-consuming, require extensivesample preparation, are destructive, or even require alarge amount of sample, their application to originals,even for microanalysis, is hardly conceivable.

For these reasons, an NIR (near infrared) spectroscopicanalytical technique was developed potentially enablingus to evaluate whole collections within a reasonabletimeframe.1 The technique does not require any samplepreparation; collection and evaluation of a spectrum is astraightforward procedure, and it is non-destructive.Using an additionally developed software tool NIR-PR(NIR Paper Rating), safe evaluation of the condition ofan artefact or even a collection is possible. The use ofNIR spectroscopy for characterization of paper is well-known and has already been used in paper degradationstudies.2

The NIR-PR tool makes use of standardizedmeasurement categories (parameters) which are used todescribe the state of degradation.1 Among these,mechanical properties, degree of polymerization (DP),lignin content and pH are undoubtedly the mostimportant, although other parameters such as carbonylgroup content can also be determined. The basis for anyquantitative NIR method development is a good set ofreference data. These must be obtained from a large andwell representative set of sample papers of historicalorigin.

The data of chemical; and predominantly mechanicalcharacterization were subsequently correlated with NIRspectra using advanced chemometric (statistical andmathematical) methods, e.g. multivariate statistics.From the obtained correlations, the state of degradationof a certain sample can be evaluated.

In this contribution, we will shortly review the state ofthe art of the methodology and explore some futureneeds and prospects.

1. Method developmentAs a result of a considerable number of analyses, aclassification model has been developed andimplemented in the NIR-PR tool.

The classification according to the NIR-PR tool is donein the following way. After spectroscopiccharacterization of a sample, evaluation of the state ofdegradation according to the determined physical andchemical parameters is performed on the basis of pre-set criteria. These criteria are independent of the generalstrategic preservation plan, and are selected in order tomirror the decision-making system on the basis ofwhich a sample is considered more or less stable. Aninclusion of a proposal of a treatment strategy in theNIR-PR is optional. The recommendation regarding theapplicability of mass deacidification can also beincluded (Fig. 1).

On the basis of such a model three ratings are given:States 1, 3 and 5. With an increased set of data in futureinvestigations a finer division and better definition ofthe thresholds 1–3 and 3–5 is planned.

In order to obtain a satisfactory set of workable data,more than 100 different wood pulp and cellulose papersproduced between 1886 and 1993 were analyzed in adestructive way. The real historical samples wereobtained from a variety of sources in Germany – in thephase of method development, we have not attemptedto obtain a sample set representative for a variety ofpaper sources and geographical origins. Among themore important parameters, tensile strength (Fmax) in themachine direction and intrinsic viscosity weredetermined. The definition of limits of the Groups andStates in Figure 1 was done according to the obtained

Group 1Good condition State 1

Group 2Intermediate conditionGroup 3Acceptable condition State 3

Group 4Bad conditionGroup 5Very bad condition (decrease of State 5stability after mass deacidification)

Figure 1: Classification model for the rating of papercondition.


data. After the limits were defined, the data obtainedfrom NIR spectra by chemometric evaluation weregrouped accordingly.

Additionally, as the individual properties are not allequally significant for the definition of paper condition,statistical weights had to be associated with eachproperty.

In order to minimise the error associated with NIR-PR,separate methods were developed for the two sets ofsamples: wood pulp and bleached cellulose/cotton. Thiswas necessary due to the widely different spectralcharacteristics. Besides, the intervals of measuredchemical and mechanical parameters depended on thepaper variety very much. E.g., lower tensile strengthFmax was determined in wood pulp papers than incelluloses as a rule.

In order to enable this division into two categories, thelignin content of papers was characterized duringspectroscopic evaluation first: if lignin content wasfound to be lower than 10%, the sample wascharacterised as bleached cellulose/cotton paper.

2. ExperimentalNIR is the spectral area between visible and meaninfrared light (12,000–4,000 cm-1, i.e. 850–2,500 nm).Absorption of light in this interval of wavelengthscorresponds to a great variety of combination andovertones, which increases the information content ofthe spectrum. Its exact analytical interpretation istherefore hardly possible. However, using thechemometric approach, the complex interrelatedinformation within a spectrum is reduced to a fewspecific basic patterns (absorption bands), theparameters of which can then be correlated with knownproperties of the measured system, i.e. paper. Suchtreatment of NIR spectra allows for easy, fast andchemical-free quantitative analyses.

The spectra are obtained on the basis of trans-flection(transmission and reflection): the sample is irradiatedwith non-destructive NIR light from an integratedsource and the reflected spectrum is recorded using anarray detector. High reproducibility can be achieved ifgood resolution and thermal stability can be assured.

The NIR system developed by our group consists of aportable dispersive NIR spectrometer with a speciallyconstructed external “sampling head” for solidmaterials, which is connected to the spectrometer bymeans of an optical fibre and is equipped with a samplecarrier and a plate to gently press the sample down onthe sampling head during a measurement. A computer,which is an integral part of the instrument, allows forimmediate display of the results (Figure 2).

The paper to be characterized is placed on the outlet ofthe external light source. In order to assure highprecision, at least three consecutive measurements arecarried out per evaluation in three or more different

parts of the sample (measurement spots). The spotsshould be selected in a statistical manner in order totake into account possible sample inhomogeneities. Therecorded spectra are automatically averaged, followedby an instant display of the rating according to the NIR-PR tool. The required time of analysis per objectdepends on the required sample handling: for the actualrecording of spectra and calculating the results,milliseconds are needed.

Due to the large penetration depth of NIR light,measurements have to be carried out on several layersof paper or with a ceramic background such as the oneused for calibration. Text on the paper does notinterfere with measurements; however, sections withhigh colour saturation (e.g. illustrations with a highpercentage of black pigments) are to be avoided.While only minimal pressure against the samplinghead is sufficient for a book, a metal plate should beused for loose sheets in order to obtain higherreproducibility.

3. Software toolThe elaborated method was integrated into a Microsoft-Windows-based software application with anappropriate user interface. The combination of thespectrometer and application software enables theoperator to start evaluation with a mouse click. Afterhaving chosen a specific file and entering anappropriate sample description, internal calibration ofthe system and measurement is started by the software,automatically. The evaluation progress is displayed onthe monitor. As a result, the paper condition isdisplayed, described by the state (Figure 1).

For the evaluation of large collections, the results arecompiled in a table. The number of characterizedsamples is not limited. In addition to sampledescription, a commentary, as well as the date and timeare optional parameters. Certainly, the results of allindividual measurement categories are also compiled inthe file, which can be easily converted into a MicrosoftExcel file or other similar application.

Figure 2: NIR spectrometer with the periphery.


4. OutlookWood pulp and bleached cellulose containing acidicpapers account for a greater part of endangered papercollections in libraries, museums and archives. NIR-PRenables us to survey the condition of such collectionson a scientific basis in a repeatable manner. It is alsouseful to monitor the ageing behaviour of collections byperforming repeated evaluations. The non-destructiveNIR-PR evaluation represents a powerful tool which

enables the collection manager to plan efficientpreservation strategies.

In the EC 6th Framework research project SurveNIR wewill considerably expand the sample sets with regard tothe geographical and material characteristics (date andtype of production) thus extending the possibilities ofthe NIR-PR for surveying extremely large and variablecollections.


FOLLOWING OXIDATION OF CELLULOSE WITH XPSL. Fras1*, K. Stana-Kleischek1, L.-S. Johansson2, P. Stenius3, J. Laine3, V. Ribitsch4

1 Laboratory for Characterization and Processing of Polymers, Faculty of Mechanical Engineering, University of Maribor,Smetanova 17, SI-2000 Maribor, Slovenia2 Center for Chemical Analysis, Helsinki University of Technology, P.O. Box 6100, FI-02015 HUT, Finland3 Laboratory of Forest Products Chemistry, Helsinki University of Technology, P.O. Box 6300, FI-02015 HUT, Finland4 Institute of Chemistry, Rheology & Colloid Science, Karl Franzens University, Heinrichstraße 28, AT-8010 Graz, Austria

* Corresponding author: [email protected]

During its production and processing, cellulose ismodified both chemically (oxidation and hydrolysis)and structurally (type and degree of crystallinity). Thepurposes of these modifications are to change cellulosefibre reactivity (number and location of functionalgroups) and to inhibit or at least minimise possibledegradation. The processing of cellulose has aninfluence on the fibrillar structure, i.e. crystallinity ofcellulose decreases, resulting in swelling of the polymeras well as increased accessibility of active groups onthe fibre surface1. Chemical degradation can beexpected to occur primarily on amorphous cellulose andon the surface of crystallites. The borderline betweenaccessible and not accessible cellulose is not welldefined. Other changes may also take place, e.g.reorganization of cellulose chains2. Previous researchhas, however, mainly focused on analysis of the finestructure of cellulosic fibres3,4. Much less attention hasbeen given to the reactivity of cellulose fibre surfaces,which is a consequence of reactions on fibre surfaceand correlates with charge.

The charge of cotton fibres, due to dissociation ofacidic groups in neutral or alkaline conditions, mayoriginate from the original chemical composition of thefibre wall but also from changes during the differentprocess steps2. Some pre-treatment processes lead to adecreased number of acidic groups; while during othersnew acidic groups may be generated5. The variation ofdissociable acidic groups and, consequently, of chargehas an influence on the adsorption capacity and,therefore, on fibre reactivity.

In this work cotton fibres were oxidized with the aim tochange the total charge (content of accessible acidicgroups) and surface charge (content of acidic groups onthe fibre surface). Oxidation of fibres was doneselectively with potassium periodate(VII) followed bysodium chlorite(III). It has been shown that oxidation inthis way may cause carboxyl groups to be introducedmainly at the C2 and C3 positions5,6.

The purpose of this study was to evaluate how selectiveoxidation affects surface properties of fibres. Anothervery important objective was to compare differentmethods and evaluate whether they are applicable andsensitive enough to observe the changes in nature,content and accessibility of acidic groups in the fibres,with special emphasis on the X-ray PhotoelectronSpectroscopy (XPS).

X-ray Photoelectron Spectroscopy has recently gainedmuch attention in the analysis of organic materials. Dueto an analysis depth of only a few nanometers and easyelemental quantification, the technique has been usedfor surface characterization of inorganic materials fordecades. In the case of organic fibres, the surfacesensitivity and enhanced energy resolution of moderninstrumentation, which enables quantitativedetermination of differently bonded carbon atoms, havemade this technique a valuable research tool7.

XPS has been mostly used to analyze pulp8-11 andexopolysaccharides12. When characterizinglignocellulosic materials, two alternative methods canbe used. The first is based on quantitative elementalanalysis of the surface, where the O/C ratio, which isdifferent for cellulose, lignin, and extractive, is used. Inthe second method, differently bonded carbon atomsand, consequently, different functional groups on thesurface are determined quantitatively from high-resolution spectra by means of deconvolution. In thiscase, the component at 285 eV, which is due to carbonswithout oxygen bonds, can be used to determine surfacecoverage of lignin and extractives7.

In this work, surface chemistry of oxidised cotton fibresis analyzed with XPS. In addition to this method,polyelectrolyte titration was used to obtain informationabout charge location and accessibility of chargedgroups. The results from XPS were combined withthose obtained by polyelectrolyte titration in order toobtain a consistent picture of the location of dissociablegroups on the fibre surface.

The combination of XPS with titration confirms thepresence of two processes during oxidation: lowmolecular fraction elimination and new acidic groupformation in the cellulose chains. Domination of bothprocesses is dependent on oxidation time, but the firstone is more effective. The XPS method confirms thatthe surface concentration of acidic groups isconsiderably lower than the bulk concentration. Thissuggests that during oxidation the content of carboxylgroups on the surface decreases, while in amorphousregions it increases. The first is the consequence of“cleaning” effect; the second is the consequence offormation of new acidic groups. During the oxidation,the small periodate ion might be able to enter thecellulose fiber interior and the glucose unit may beoxidized at C2 and C3 so that new – CHO are formed


inside of fibres13. In the second oxidation step thesegroups inside of fibers are oxidized to carboxyl groups.

The use of XPS analysis in combination with titrationmethod seems to be very promising for the futureobservation of the influence of chemical modification,e.g. oxidation, on the fibre surfaces for textile as well asfor paper use. Therefore, these methods could be usefulas a control tool for determination the degree ofdegradation, until fibres still keep suitable practicalcharacteristics.

References1. H. A. Krässig, Cellulose, Structure, Accessibility and Reactivity,

Gordon and Breach Science Publishers, Switzerland, 1993.2. L. Wägberg, G. Annergren, Physicochemical characterization of

papermaking fibres, Fundam. Papermaking Mater., Trans.Fundam. Res. Symp., 11th, Cambridge, UK, 1997.

3. T. Kreze, S. Jeler, S. Strnad, Correlation between structurecharacteristics and adsorption properties of regeneratedcellulose fibres, Mat. Res Innovat, 2001, 5, 277–283.

4. T. Kreze, S. Strnad, K. Stana-Kleinschek, V. Ribitsch, Influenceof aqueous medium on mechanical properties of conventionaland new environmentally friendly regenerated cellulose fibers,Mat. Res. Innovat, 2001, 4, 107–114.

5. B. L. Browning, Methods of Wood Chemistry, IntersciencePublisher, New York, 1967.

6. L. Fras, K. Stana-Kleinschek, V. Ribitsch, M. Sfiligoj-Smole, T.Kreze, Quantitative determination of carboxyl groups incellulose by complexometric titration, Lenzing. Ber., 2002, 81,80–88.

7. J. Buchert, J. Pere, L. S. Johansson, J. M. Campbell, Analysis ofthe Surface Chemistry of Linen and Cotton Fabrics, J. Textile.Res., 2001, 71, 626–629.

8. G. M. Dorris, D. G. Gray, The Surface Analysis of Paper andWood Fibres by ESCA, I: Application to Cellulose and Lignin,Cellul. Chem. Technol., 1978, 12, 9–23.

9. G. M. Dorris, D. G. Gray, The Surface Analysis of Paper andWood Fibres by ESCA, II: Surface Composition of MechanicalPulps, Cellul. Chem. Technol., 1978, 12, 721–734.

10. L. S. Johansson, J. M. Campbell, K. Koljonen, P. Stenius,Evaluation of Surface Lignin on Cellulose Fibers with XPS,Appl. Surface Sci., 1999, 144-145, 92–95.

11. J. Laine, P. Stenius, G. Carlson, G. Ström, SurfaceCharacterization of Unbleached Kraft Pulps by Means of ESCA,Cellulose, 1994, 1(2), 145–160.

12. L. S. Johansson, T. Saastamoinen, Investigating Early Stages ofBiocorrosion with XPS: AISI 34 Stainlees Steel Exposed toBurkholderia sp., Appl. Surf. Sci., 1999, 144–145, 244–248.

13. X. D. Liu, N. Nishi, S.Tokura, N. Sakairi, Chitosan coatedcotton fiber: preparation and physical properties, CarbohydratePolymers 2001, 44, 233–238.


THE EVOLUTION OF A NEW ACCELERATED AGEING TEST FORPAPERChandru J. ShahaniPreservation Research and Testing Division, Library of Congress, Washington, DC, USA

*corresponding author: [email protected]

Accelerated ageing tests are at the heart of keypreservation management decisions, for it is throughthese tests that we learn how materials age and how wecan control the environment, or provide a chemicaltreatment such as deacidification, or avoid exposure toharmful chemicals, and thus extend the useful life ofour treasured collections. Therefore, it can befrustrating if accelerated ageing tests, which make upthe very foundation for our preservation actions, arethemselves built on questionable assumptions. Whilewe have had no option but to continue the use of suchtests for the lack of a better option, the literature isreplete with nagging doubts and questions about theirreliability.1-5 In the formulation of standards forpermanent paper, while accelerated aging tests are oftenspecified as options, they have rarely been required.Instead, we have learned to place our faith on compo-sitional requirements such as a minimum level ofalkaline reserve and the near-absence of lignin to definepermanent paper, even though this approach does notalways make good sense. For example, cotton papers,which have already been proven to be one of the mostpermanent papers, would not meet the requirements ofmost present-day standards for permanent paper sincethey would fail the alkaline reserve and pH require-ments. Even worse, overly recycled papers of poorquality with minimal strength but with the rightcompositional content can potentially pass muster aspermanent papers.

In order to move from composition-based standardstowards performance-based standards, we need todevelop an accelerated ageing test in which we canhave a high enough degree of confidence so that we canlet go of the protection that a composition-basedstandard can provide us. To achieve this reality,research at the Library of Congress was focusedthroughout the nineteen nineties on the development ofan accelerated test that would simulate the ageing ofpaper in real life, and settle forever the debate about thevalue of accelerated aging tests that has raged at leastsince George Richter recognized in 1934 that “…therewill probably continue to be two schools of thought onthe relative merits of (accelerated ageing tests) – thosewho believe in them and those who do not.”6 With theresearch we present here we hope to be able to movetowards a single school of true believers. Instead offollowing the oft-trodden path of expounding thelinearity of Arrhenius plots through a limited range ofelevated temperature and relative humidity conditions,we focused on a comparison of the chemical productswhich result from the ageing of paper. In particular, we

analyzed papers aged naturally as well as by acceleratedageing for carbohydrate species using ion chromato-graphy and aliphatic acids such as formic and acetic,which we discovered form in surprisingly abundantconcentrations, by capillary electrophoresis. Test paperswere selected with a view to extend the study to thegreatest variety of papers, and included acidic as well asalkaline papers made from cotton, bleached northernsoftwood kraft and groundwood pulps. These six paperswere aged as loose sheets (which has been the norm formost accelerated ageing tests), as book-like stacks andinside air-tight glass tubes. The choice of these threeageing configurations was based on our earlier work,which had shown us that acidic degradation productstend to accumulate inside polyester encapsulations andother enclosures, and thereby hasten the ageing ofpaper.7,8 The similarity of the nature of degradationproducts formed under natural ageing and underaccelerated ageing within glass tubes was most strikingas demonstrated by the chemical analysis for thecarbohydrate and acid species formed in the ageingprocess. These data provided unequivocal proof of thegreat similarity between reaction mechanisms under-lying the natural and accelerated ageing processes. Onthe other hand, lower rates of degradation wereobserved for experiments carried out with loose sheets.It was also clear that in these experiments the volatileacids were not being retained within the paper matrix.This work resulted in the development of an acceleratedageing test in which paper samples conditioned under astandard environment are aged inside airtight glasstubes at 100 °C for 5 days to gauge the retention oftheir original strength properties. The lowest strengthloss, preferably no more than 20 percent, qualifies thepaper to be of the highest permanence quality regard-less of its chemical composition. Since this test does notrequire the use of expensive ageing chambers that cansimultaneously control relative humidity and tempera-ture, it can be used by many more facilities where onlysimple ovens, which can only control temperature, maybe available. Besides the economy that it offers, thistest is also much faster since it requires only 5 days ascompared to conventional ageing tests, which generallyrequire 30 days, and even more importantly, do notsimulate the natural ageing process. This test has nowbeen adopted as an ASTM standard, and efforts for itsadoption as an ISO standard are in progress to the bestof our knowledge.

In the process of development of this test, we alsoacquired a new understanding and appreciation of thechemical mechanisms by which paper ages. Thus far,


we had blamed acidic alum-rosin sizing and environ-mental pollutants for the inexorable embrittlement ofour ageing book and manuscript collections. Whilethese factors do contribute to the ageing process inpaper, their contribution is not as significant as that ofthe acids that form as a result of the degradation ofcellulose and hemicelluloses as they interact withoxygen and moisture over time. The formation of theseacids leads to a self-promoting hydrolytic degradationchain reaction, or auto-catalysis, in which the acidconcentration continually builds upon itself, leading toa constantly escalating acidic environment that pro-motes an ever-increasing rate of cleavage of thecellulose molecules. These findings belie the school ofthought that the ageing process somehow reaches astate of equilibrium leading to an asymptotic conditionunder which the rate of ageing ultimately slows downalmost to a stop.The practical implications of this new understanding ofthe mechanism responsible for the ageing of paper arehugely significant as well. The hitherto overlooked roleof these naturally generated acids in catalyzing thehydrolysis of the cellulose molecule is also thefundamental reason for the non-correspondence of otheraccelerated ageing tests with the natural ageing processsince these accelerated ageing tests allow the acidswhich cause the most damage to escape freely, andthereby paint a less than accurate picture of the real rateof ageing. Because of reliance on such faulty tests, wehave grossly underestimated the benefit that can bederived from deacidification. Likewise, we haveunderestimated the harm that can be done by highrelative humidity conditions since exposure of looseageing sheets to higher humidity conditions, at which

the abundance of water molecules as well as theelevated temperature levels force the acid moleculesformed in the ageing process to escape into theenvironment. In real life, hydrogen bonding enablesretention of newly formed acid molecules within thepaper matrix. The efficiency of acid retention is evenhigher when the paper is prevented from interactionwith air as when it is situated within the body of a book,or a picture frame, or a polyester capsule.

Therefore, the threats from humid environments anddeveloping acidic conditions in paper are appreciablyhigher in real life that estimates from conventionalaccelerated aging tests would have us believe. The newaccelerated aging test presented here overcomes thesedrawbacks.

References1. P. Luner, Tappi, 1969, 52, 796.

2. E. Ströfer-Hua, Restaurator, 1990, 11 (4), 254–266.

3. H. Bansa, Restaurator, 1992, 13, 114–137.

4. J. D. Priest, “Artificial aging of paper: Correlation with naturalaging,” ASTM Workshop on the Effects of Aging on Printingand Writing Papers, ASTM, Philadelphia, PA, 1994.

5. H. J. Porck, Rate of degradation: The predictive value ofartificial aging tests, European Committee on Preservation andAccess, Amsterdam, 2000.

6. G. A. Richter, Ind. Engineering Chem., 1934, 26, 1154–1157.

7. C, J, Shahani, F. H. Hengemihle and N. Weberg, “The effect ofvariations in relative humidity on the aging of paper,” Amer.Chem. Soc. Symposium Series 410, Zeronian, S. H. and H. L.Needles (Eds.) Historic Textiles and Paper Materials II:Conservation and Characterization, American Chemical Society,Washington, DC, 1989, pp. 63–80.

8. Shahani, C. J., “Can accelerated aging foretell the permanenceof paper,” ASTM Workshop on the Effects of Aging on Printingand Writing Papers, ASTM, Philadelphia, PA, 1994.


THE CONCEPT OF MIXED-CONTROL MECHANISMS AND ITSAPPLICABILITY TO PAPER DEGRADATION STUDIESA. Barański*1,2, J. M. Łagan2, T. Łojewski1

1 Jagiellonian University, Department of Chemistry, Kraków, Poland2 Jagiellonian University, Regional Laboratory for Phys-Chem. Analyses and Structural Research, Kraków, Poland


1. GenesisAccelerating ageing, its importance and necessity ofanalyzing the data thus obtained, have been alreadyemphasized by Porck1. He pointed out that “the smallnumber of research projects that have tried to verify thepredictive value of artificial aging analysis stronglycontrasts with the widespread use of this analysis inpractice”.

The analysis is based on the use of Arrhenius equationfor extrapolation of kinetic data. Hence application ofthe equation to the description of complex phenomenaof cellulose degradation, being the problem typical ofpreservation science, will be discussed below.

2. FundamentalsFundamentals of the chemical kinetics should berecalled here. If one wants to use Arrhenius equationfor the description of temperature dependence of rateconstants, then one must be sure that the consideredkinetic equation is in agreement with the results ofisothermal experiments in the whole range oftemperatures studied. When the kinetic equation issimple (an elementary step or rate determining step(rds) of a complex reaction are the examples) theapplication of Arrhenius relation is straightforward.However, in the more general case, when rds is absent,kinetic equation is more complicated, and it containstwo or more rate constants. This implies the use of twoor more Arrhenius plots for the interpolation orextrapolation of kinetic data within a temperature range.

Taking into account another fundamental premise – areaction mechanism cannot be proven by kinetic data;it can be, however, easily excluded – let us consider thefollowing example.

3. Hydrolytic and oxidative pathways of mixed-control mechanism of cellulose degradation

The rate of acid hydrolysis is described by theEkenstam equation. If, under certain conditions, thisequation does not hold, then acid hydrolysis cannot bethe only pathway of cellulose degradation. The resultsof the kinetic studies dealing with applicability ofEkenstam equation2 have been summarised in Fig. 1.

Model paper samples containing cellulose only, pureand impregnated with aluminium sulphate, have beenaged for 2–21 days within the temperature range 40–

100 °C. Every kinetic curve, characterized bytemperature (°C) and Al content (‰ by weight) hasbeen indicated by a single point in Fig. 1. On theabscissa, the deviation of the curves from Ekenstamequation has been shown.

It was indicated in publication2 that within the shadedarea of Fig. 1 a single degradation route (this being acidhydrolysis) dominates, whereas outside the area (i.e. athigher temperature and higher Al content) oxidation ofcellulose should also be taken into account. Thus Arrhe-nius equation can be safely applied to the rate constantof Ekenstam equation inside the shaded area only.

Two degradation routes exist outside the area – acidhydrolysis and oxidation – and, therefore, the Ekenstamequation does not hold. Another, at this time unknown,equation (let’s call it a mixed-control equation) willproperly describe the kinetic data. The postulatedequation will contain two rate constants – kh and kox –for acid hydrolysis and oxidation respectively. Therewill be two Arrhenius plots: ln(kh) versus 1/T and ln(kox)versus 1/T , and, consequently, two activation energiescan be calculated. It seems obvious that continuitybehaviour should be observed in such a case. One canexpect that the mixed-control equation, when extendedto the low-temperature region (inside the regionencircled by the borderline in Fig. 1), will yieldEkenstam equation as the limiting case. Therefore theArrhenius plot for kh should be valid (i.e. no sharpdirection changes observed) in the whole range ofexperimental conditions – outside and inside the Fig. 1borderline. On the other hand, as assumed, the kinetic

Figure 1: Residual standard deviations (expressed as DPvalues), obtained for paper samples impregnated with variousamounts of Al, as a function of temperature. Taken from ref.2 – however, in the description of the original drawing, time(days) has been indicated erroneously instead of temperature(deg).


data providing kox values are restricted only to thetemperatures outside the borderline. This is why theextrapolation of kox value to the temperatures below theborderline should be avoided.

4. The concept of Arney and Novak revisitedThe ideas outlined just above can be emphasized bytaking into account the publication by Arney andNovak3 entitled informatively “Accelerated Ageing ofPaper. The Influence of Acidity on the relative Contri-bution of Oxygen-Dependent and Oxygen-IndependentProcesses”. Arney concludes that the rate of paperdegradation is a sum of four terms, depending on (i)oxygen pressure, (ii) pH value, (iii) both oxygenpressure and pH, and (iv) neither oxygen nor pH.Hence, there are four rate constants, and, consequently,four Arrhenius plots could be drawn. In fact, a complexmixed-control mechanism is taken into account in thepublication in question.

5. The case of metallurgyThere is nothing new in the concept of mixed-controlmechanisms. The idea can be directly linked to thefundamentals of chemical kinetics. If no rate-determining step can be postulated, then one shouldsuggest a kinetic equation considering two or moreelementary steps occurring with similar rates andcontributing to the overall reaction rate in a similarway. This idea, initially introduced in solid-statechemistry in mid-twentieth century, has beensuccessfully extended in the research on solid-gasreactions, being of primary importance in metallurgicalprocesses. An extremely simplified example would helpthe reader to understand the concept in question.

Let us consider the reduction of iron ore grains byhydrogen. The shape of grains is considered as beingapproximately spherical. The reduction temperature andthe grain radius are variables equally important as thetemperature and pH of paper in the process of cellulosedegradation. The reaction of oxide reduction on thegrain surface and diffusion of water vapour and hydro-gen within the porous structure of the grain are partialprocesses of the overall reduction of ore; similarly acidhydrolysis and oxidation are partial processes of theoverall process of cellulose degradation.

Fig. 2 has been redrawn after the already classicaldrawing published in the monograph of Szekely4. Threezones can be observed in this Figure: that of chemicalcontrol, diffusion control and mixed control:

– in the region of chemical control the chemicalreaction is a rate-determining step, and a kineticequation has one term containing only one parameter:reaction rate constant;

– in the diffusion control region the gas (H2, H2O)diffusion in the pores of solid is a rate-determiningstep, and the kinetic equation has only one termcontaining only one parameter characterizing the

diffusion phenomena in solid – e.g. effectivediffusivity;

– in the mixed-control region there is no rate-determining step, and the kinetic equation consists oftwo terms – called reaction term and diffusion term –containing two parameters: reaction rate constant andeffective diffusivity, respectively.

One can easily notice that the kinetic equations valid inthe regions of chemical control and diffusion controlare boundary cases of the more general equation

describing the overall reduction process in the mixed-control region. Examples of mixed-control equationscan be found in the textbooks by Levenspiel5, 6.

6. ConclusionsThe success of extrapolation procedure during theanalysis of accelerated ageing experiments depends ongetting the proper mixed-control description ofdegradation phenomena within the high-temperaturerange. Not enough primary kinetic data, enablingcharacterization of simultaneous hydrolytic andoxidative degradation of cellulose, can be found inliterature. The advance of both processes should beindependently determined by properly plannedexperiments. It is obvious that model samples of papershould be studied first.

7. References1. H. J. Porck, Rate of paper degradation. The predictive value of

artificial aging tests, European Commission on Preservation andAccess, Amsterdam, 2000.

2. A. Barański, R. Dziembaj, A. Konieczna-Molenda, J. M. Łagan,S. Walas, On the applicability of Arrhenius equation toaccelerated ageing tests. The case of alum-impregnatedcellulose, Polish Journal of Chemical Technology, 2004, 6, 1–8.

3. J. S. Arney, C. L. Novak, Accelerated Aging of Paper. Theinfluence of acidity on the relative contribution of oxygen-dependent processes, TAPPI, 1982, 65, 113.

4. J. Szekely, J. W. Evans, H. Y. Sohn, Gas-Solid Reactions,Academic Press, 1976, 73–88.

5. O. Levenspiel, The Chemical Reactor Omnibook, OSUBookstores, Corvallis, OR, 1989, Chapter 51.

6. O. Levenspiel, Chemical Reaction Engineering, 3rd Edition, J.Wiley & Sons, New York, 1999, Chapter 25.

Figure 2: Three zones of reaction control.


APPLICATION OF UV-ABSORBERS AND RADICAL SCAVENGERS INTHE PHOTO-STABILIZATION OF PRINTING PAPERSM. Beyer*, A. Geerds, K. FischerInstitute of Plant and Wood Chemistry, Dresden University of Technology, Pienner Str. 19, D-01737 Tharandt, Germany


1. IntroductionPapers made of mechanical pulps as well as agedcellulosic materials contain lignin or other phenoliccomponents. When exposed to daylight, they mayexhibit pronounced yellowing that decreases theirreadability and possibly mechanical strength. Duringthe past decades, much research was devoted towardsunderstanding the main reaction pathways andstructures of coloured compounds.1-3 It was shown thatphoto-irradiation induces cleavage of lignin ether bondsto produce phenoxyl or phenoxyalkyl radicals which inturn react with oxygen. The result is the formation ofbenzoquinone derivatives that absorb light in the violetand visible region.

In order to inhibit the photo-induced processes, a greatnumber of different compounds, their combinations aswell as the effect of chemical modification of pulpswere studied.4-6

Combined applications of UV screens and radicalscavengers were the most successful. It was observedthat in this way a synergistic effect can be obtainedleading to a decreasing demand for stabilizers.7-9 Theinhibiting compounds are usually sprayed or pouredover the paper surface. This can be an obstacle for theiruse in industrial papermaking due to the lack of anappropriate technology. In addition, radical scavengershave the most pronounced effect if they are close to thesites of radical formation, i.e. where lignin is localized.On the other hand, UV absorbers have the optimumeffect on the paper surface. Therefore the applicationtechniques have to be different for these two types ofinhibitors.

2. ExperimentalIn the present study, a stabilising effect ofhydroxyphenyl benzotriazol-type UV absorberscombined with novel radical scavengers based onsulphur-containing amino acids was investigated inapplications on surface-sized or surface coated systems.For the investigations, model papers made of a mixtureof an ECF-bleached sulphate pulp and a bleachedmechanical pulp with an increasing fraction of themechanical pulp were used. The irradiation was carriedout in a Xenotest 150S unit at 20 °C and 50% relativehumidity. Optical properties of the papers werecharacterized by their ISO brightness or CIE L*a*b*colour data.

3. Results and discussionIn the first experiment, paper samples were sized withan aqueous solution of polyvinyl alcohol (3 g m-2)containing different amounts of the radical scavengeracetyl cysteine. The results are shown in Table 1.

Table 1: Application of surface sizing with acetyl cysteine topaper containing 30% mechanical pulp.

Brightness after irradiation (%)0 h 10 h 20 h

No sizing 83.8 60.6 55.8Sizing without stabilizer 81.4 60.4 56.1Sizing with 0.5 % stabilizer 84.8 62.1 56.5Sizing with 1.0 % stabilizer 85.6 63.9 58.5

These results demonstrate that a single application ofthe radical scavenger has only a minor stabilisingeffect. To cover the paper surface, a thin coating ofpolystyrene-polybutadiene coating with calciumcarbonate and china clay pigments was used. Theaddition of a UV screen (Ciba Tinuvin 328) led tofurther stabilization (Table 2).

Table 2: Brightness stabilization by a coating colourcontaining a UV screen.

Content of UVA Brightness after irradiation (%)in coating colour (%) 0 h 10 h 20 h0 83.2 68.1 63.40.5 81.0 67.9 63.61.0 81.1 69.2 64.52.0 81.9 71.6 67.63.5 83.3 77.7 74.6

In comparison with the uncoated sample, the coatingitself has a remarkable effect on brightness stability.When 3.5% of the UV screen is applied, brightnessafter 20 h irradiation increased by another 10%.

When both types of inhibiting systems where appliedonto paper surface, their mutual impact exceeded thatof the sum of the single components. With 1% of acetylcysteine in the surface sizing and 2% of the UV screenin the coating colour, brightness of 70.3% was obtainedafter 20 h of irradiation.

4. ConclusionsThese results led to the conclusion that a combinationof stabilisers may be interesting also from the point ofview of conservation, since especially the papermanufactured during the 19th and the beginning of the20th century contain considerable amounts of lignin or


may incorporate low molecular phenolic compoundsdue to ageing processes. These papers will undergolight-induced discolouration. Coating these materialswith very thin layers of combinations of stabilizerspresented in this study could help to preserve theiroptical properties as well as mechanical strength for along period.

5. References1. J. S. Gratzl, Lichtinduzierte Vergilbung von Zellstoffen –

Ursachen und Verhütung, Papier, 1985, 39, V14–V23.2. G. Gellerstedt, L. Zhang, Formation and reactions of

leucochromophoric structures in high-yield pulping, J. WoodChem. Technol., 1992, 12, 387–412.

3. C. Heitner, J. A. Schmidt, Light-induced yellowing of wood-containing papers – a review of fifty years of research, Proc. 6thISWPC, Melbourne, Australia, 1991, 131–149.

4. T. Q. Hu, G. R. Cairns, B. R. James, Removal of phenolichydroxyl groups in lignin model compounds and its effect onphotostability, Holzforschung, 2000, 54, 127–132.

5. M. Paulsson, J. Parkås, Chemical modification ofchemithermomechanical pulps part 1: mechanical, optical, andaging properties of propionylated spruce CTMP, J. Wood Chem.Technol., 2000, 20, 205–224.

6. J. Janson, I. Forsskahl, Polytetrahydrofuran – a polymer thatcounteracts colour reversion, Nord. Pulp Pap. Res. J., 1996, 11,10–14.

7. K. Fischer, I. Schmidt, H. Koch, The role of oxygen species atlight-induced yellowing and possibilities to reduce their action,Proc 6th ISWPC, Melbourne, Australia, 1991, 431–437.

8. Z. Yuan, J. Schmidt, C. Heitner, M. Fairbank, Application ofyellowing inhibitors to improve the brightness stability of coatedmechanical papers, Tappi J., 2003, 2, 9–15.

9. M. Beyer, K. Krasselt, K. Fischer, H. Jakob, H.-U. Süss,Yellowing inhibitors for bleached mechanical pulps –investigations into the mechanisms of their acting, Proceedings2001 International Mechanical Pulping Conference. Helsinki,Finland, 4–8 June, 2001, 445–452.


DEGRADATION OF CELLULOSE HANDSHEETS AS STUDIED BYBEGIN AND KAMINSKA METHODT. Łojewski*1, A. Barański1,2, J. M. Łagan2, T. Sawoszczuk1 and K. Zięba1

1 Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow, Poland2 Regional Laboratory of Physicochemical Analyses and Structural Research, Ingardena 3, 30-060 Krakow, Poland


The method of accelerated aging developed byCanadian Conservation Institute (CCI) and Library ofCongress, and recently accepted by ASTM as a newstandard (ASTM D 6819-02), intends to mimic themechanical and chemical changes occurring in paperunder natural conditions in a new way. 1 A wide arrayof existing methods and standards (see: 2) does not takeinto account the factor evident to every reader openingan old book – its odour. In an aging experiment withfree-hanging separate sheets of paper, the degradationproducts can be easily desorbed from the sheets, thusnot affecting paper degradation any further – in contrastto real situation, where closed books or archivematerials are tightly packed on shelves.

1. Reproducibility of the proposed test methodA series of samples used in the ASTM/ISR study wasaged according to the ASTM D 6819-02 method andtested for the retention of their folding endurance, zero-span tensile strength and tear index. Results ofmeasurements were compared with those published inthe CCI report.3 Tests have been performed at bothrecommended temperatures: at 90 °C for 14 days and at100 °C for 5 days. Obtained results are consistent withthe published data.3 The values of double fold and tearindex measured for samples aged at 100 °C arecompared in Fig 1 and Fig. 2.

Noticed discrepancies can be attributed to theconsiderable measurement error, typical of mechanicalproperties of paper. Additionally, sealing of the usedglass tubes is an important factor for the lab-to-labrepeatability.

2. Sealing of tubesIt has been found that recommended glass tubes do notallow to obtain a perfect seal at the aging conditions(Lab-line No. 308-9 and Kontes No. K736500-3515).Silicone rubber O-rings and Teflon resin gaskets usedin the available hybridization tubes, although mechani-cally and chemically stable well above 100 °C, areconsiderably gas-permeable at the aging temperatures.The water loss from the tubes was observed bymeasuring the moisture content of the paper duringaging (IR through-the-glass moisture-meter, Fibro). Itwas additionally confirmed by weighing the tubes afterthe prolonged times of aging. Flat, 2 mm thick disk,made of Viton fluoroelastomer (Du Pont Dow) werefound to have satisfying sealing qualities. Additionally,

to ensure tight sealing, the standard polypropylenescrew caps were replaced with caps made of glass-fibrereinforced PPS (polyphenylsiloxan) (Bola H993-45,Germany) which were tightened on a tube with adynamometric wrench at 18 Nm.

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Figure 1: Folding endurance for ASTM/ISR samplesmeasured at Jagiellonian University and CCI. Glass tubeaging, 5 days, 100 °C.

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Figure 2: Tear index values for ASTM/ISR samplesmeasured at Jagiellonian University and CCI. Glass tubeaging, 5 days, 100 °C.

3. RH inside the tubeAn attempt was made to verify the actual agingconditions inside the tube, i.e the RH of air and thesample moisture content.

Since opening the sealed tube containing the testedsample will invariably lead to a sudden change of itsmoisture content, the only way to determine thiscontent is by an in-situ measurement. Such ameasurement could be carried out either with the use ofa moisture sensor placed inside the tube during theaging test or by a moisture meter located outside thetube and capable of measuring the moisture contentthrough the glass. The latter method has been applied(Fibro MCA 1410 Moisture Content Analyzer), and theRH of air inside the tube during aging at 90 °C was


established as 59% for a sample of the model paper P1.4

This result shows that the conditions of aging in sealedtubes differ significantly from those established in theASTM/ISR research program. 3

Moisture content of paper P1 at various RH wasmeasured in the climatic chamber at 90 °C. Using theobtained relation (shown in Figure 3) for the sametemperature, the relative humidity in the glass tube withP1 paper was calculated from the IR moisturemeasurement for the sample. Additionally, under suchconditions the total gas pressure inside the tube wasdetermined not to exceed 2 atm.

4. Degradation rateThe P1 paper samples used for the studies ofdegradation rate were aged in sealed tubes at 90 °C. Foreach aging time, the degree of polimerization wasmeasured (viscometrically) for samples from at leasttwo different tubes. The kinetic curve (in the linearizedcoordination system) obtained for the samples agedwith the new technique is presented in Figure 4. Therate constant of paper degradation was calculatedaccording to the Ekenstam equation. The found value ofthe rate constant (k = 2.3*10-5 ) correlates well with theresults of our previous study, where P1 paper samples

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were aged in closed vessels containing saturatedsolutions of salts. 5 Using the relation between k and RHpresented in the referred work, the rate constant for theconditions inside sealed tube with P1 paper could beestimated as 2.9*10-5.

In this work the discussed kinetic curve have been alsorelated to other kinetic curves obtained for P1 paperaged under similar conditions (T, RH) but as free hungsheets in a climatic chamber.

5. References1. P. L. Bégin, E. Kaminska, Thermal Accelerated Ageing Test

Method Development, Restaurator, 2002, 23, 89–105.2. H. J. Porck, Rate of paper degradation. The predictive value of

artificial aging tests. European Commission on Preservation andAccess, Amsterdam, 2000.

3. E. Kaminska, P. Bégin, D. Grattan, D. Woods, A. Bullow, ASTM/ISR Research Program on the Effects of Ageing on Printing andWriting Papers: Accelerated Ageing Test Method Development,Report of Canadian Conservation Institute, CCI, 2001, No.70664.

4. J. B. G. A. Havermans, Effects of Air Pollutants on theAccelerated Ageing of Cellulose-based Materials, Restaurator,1995, 16, 209–233.

5. A. Barański, D. Dutka, R. Dziembaj, A. Konieczna-Molenda, J.M. Łagan, Effect Of Relative Humidity On The Degradation RateOf Cellulose. The Methodology Studies, Restaurator, 2004, 25,68–74.


ENCAPSULATION AND AGEING OF PAPERJohn HavermansTNO, Delft, The Netherlands

e-mail: [email protected]

during artificial ageing. The aim of our work is to find acomparable way of the ageing of paper wrapped andunwrapped by investigating the moist behaviour of thepaper and its environment during ageing.

Besides, we had the opportunity to store special papersfor about 10 years in a pouch at the National Archivesof The Netherlands. This paper presents the first resultof the effects of encapsulation of paper related to long-term storage.

2. Experimental

2.1 Materials

Two different papers were used. These papers werereceived in 1994 from a European Research Project onthe effects of air pollution on the accelerated ageing ofpaper (STEP): Paper-1, a bleached softwood cellulosepaper (pH cold water extract 6.3) and Paper-3, an acidmechanical pulp paper (pH cold water extract 5.3) 8.

The pouches applied were Archipress Archival Pouchesfrom Minigrip (Putten, The Netherlands). It is based onlaminated uncoated polyester. Bundles of 50 sheetswere encapsulated according to the Archipressspecifications using the Archipress H 1000 machine(vacuum 2–3 mbar, reached within 25 seconds).

Water sorption and desorption of paper was done with aclimate chamber and an external balance connected to adata logger. The temperature and relative humiditymeasurements were performed using PT100 andhumidicapTM sensors.

2.2 Modelling the ageing

Usually the ageing conditions are given in internationalstandards, e.g., 90 °C and 50% relative humidity9, 10.However it is obvious clear, that due to the papercontent and the way of sealing the in-pouch climate willdiffer from the out-pouch climate. Therefore watersorption and desorption behaviour of the papers usedand the in-pouch and out-pouch water activity weremeasured in a climate chamber for which firstly theclimate varied from 20 to 90 °C at a constant relativehumidity of 50% followed by changing of the relativehumidity from 50 to 80% using an interval of 5% atconstant equilibrium temperature.

The equilibrium, where the water activity of the paperin the pouch was comparable to that of paper in theageing chamber was 70 °C and 55–57% RH. Thereforeit was decided to apply an ageing climate of (70.0±0.5)°C and (55±2)% RH.

1. IntroductionOne of the preventive conservation measures to beundertaken is to avoid contact with the polluted air withthe paper stored in for example an archive. This can bedone by applying an air purification system or bystoring paper in a closed environment. There areadvantages to be mentioned when paper is beingencapsulated. For example it can reduce the storagevolume and encapsulated records are easier to transport.However, wrapping of paper by means of a polymer isunder discussion for many years1. Especially wrappingusing a light vacuum using a synthetic polymer(encapsulation). Depending of the material used forwrapping, papers ageing due to acid contaminants fromthe ambient will be reduced as the polymer will act as abarrier. Besides protecting paper against its deteriorableenvironment, the microclimate in the bundle of paperwill has its own behaviour and may have a contributionto the ageing of the wrapped paper2. In 1980 the Libraryof Congress reported in their work that polyethyleneencapsulation of paper would not enhance the ageing,especially if alkaline (deacidified) paper sealed.3 Thisconclusion was contradicted by other researchers.Passaglia concluded that the micro climate establishedwithin a closed environment could be a danger for theencapsulated paper as degradation products comingfrom the paper remain trapped and therefore couldaffect the stored paper4. Pauk and Pork showed by theirresearch, that after subjecting paper sealed in differentpolymer films to accelerated ageing (alternatingclimate), the deterioration was enhanced5.

Using a light vacuum during encapsulation will resultin low oxygen environment.,. As shown by severalresearchers, a reduced oxygen environment will reducethe deterioration of paper, however for acid paper, thedeterioration by acid catalysed hydrolyses maycontinue6, 7.

Looking at research undertaken with encapsulatedpaper, one critical point has to be considered. The wayof ageing applied differs very much. During ageing theclimate in the polymer bag or pouch have to beconsidered and none of the researchers whoinvestigated paper encapsulation have taken thisphenomenon into account. Sealed or encapsulated paperwill create its own environment as there always is anequilibrium of the water in the (micro)environment andthe paper. The water activity in the pouch is thereforeseldom comparable to the water activity of the ageingenvironment. Therefore results obtained of paperwrapped in a pouch and artificially aged can not becompared with paper hanging free in climate oven


Chemical deterioration depends on the temperatureapplied and time of ageing. Therefore we decided toapply an ageing time of 24 days at the conditions asdescriber previously. After the ageing period, chemical,physical and mechanical paper properties wereevaluated, i.e., pH of the cold water extract of the paperaccording to ISO 6588, the copper number according toASTM D 919, the brightness according to ISO 2470 ,folding number according to ISO 5626 and tensilestrength according to ISO 1924 11-15.

2.3 Natural ageing

Ten pouches were filled with 50 sheets of Paper-1 andPaper-3 respectively, according to the Archipressprocedure (see above). The pouches were stored at theNational Archives in The Hague at the storage roomlocated at the ground floor16. This storage room waskept at Archival Storage conditions, i.e., (17±1) °C and(52±3)% relative humidity17 and was also used for ourresearch on the effects of air purification on thestability of archival records which will be publishedsoon. Light at the storage room was only activated onmoments we were working in the storage room, whilethe levels of pollutants (SO2, NOx, O3) werecontinuously recorded. The papers were stored on July1995 and 2 pouches per paper grade have beenopened on July 2004. So the actual storage time was 9years.

3. Discussion

3.1 Accelerated ageing

Looking at the acidity of the encapsulated papers used,it was found that for both used papers the pH decreasesafter ageing (ÄpH for Paper-1 and Paper 3 was 0.5 and1.0, respectively), especially for the encapsulated acidmechanical paper. The acidity of the unwrapped acidmechanical paper, however, was not significantlyaffected. From the results, ir may be concluded thatacidification will continue more extensively for theencapsulated papers, than for the non-encapsulated one,due to the microclimate. Comparable results were foundin a previous research on the effects of an inert gas onthe ageing of papers7.

The copper number represents the reducing aldehydesand reactive keto groups and is therefore a goodindication for the degradation of the paper. In case ofPaper-1, the difference between encapsulated and non-encapsulated paper was not detectable. For Paper-3 theacidic paper from mechanical pulp, however, thecopper number increased for both ageing conditions,but was more severe for the encapsulated paper.According to the manufacturer, no oxygen should beable to enter the sealed pouch. Therefore we suggestthat the micro climate in the pouch, contains enoughoxygen to enable more extensive thermal oxidationwithin the closed environment than in the open one forthe lignin rich Paper-3.

Looking at the ISO Brightness of the papers used, wenotice that it decreased during ageing, however nodifferences were found due to the way of ageing, i.e.,encapsulated on open. For the mechanical properties ofthe paper, ie., tensile strength and fold number, wefound also no significant differences for encapsulatedor free papers.

3.2 Natural ageing

When opening the pouches after 9 years of storage atambient conditions, a strong smell was observed. Thesmell was stronger for Paper-3 then for Paper-1. Laterair analyses using tenax tubes and GC/MS showed thatamong the volatile compounds was acetic acid, whichcan be produced by acid hydrolyses of wood compo-nents such as lignin and polyoses18. More results of theair in the pouch will be published separately.

The pH of the cold water extract, measuredimmediately after opening the pouch, was for Paper-1and Paper-3 5.4 and 5.3 respectively. Looking at theinitial values (6.4 and 5.8 respectively), we see that forboth papers the acidity increased due to theencapsulated storage (pH 1.0 and 0.5 respectively. So,for both papers the acidity increased due to theencapsulated storage. Paper-3 also became more yellowcompared to the original papers, and to similar paper,stored at the archives in e.g. boxes19. For themechanical properties, again no significant differenceswere found between the original value and the valueafter 9 year of storage.

4. ConclusionsBased on the results of accelerated ageing at 70 °C and55% RH, the conclusion can be drawn thatencapsulation of paper using a laminated uncoatedpolyester pouch and a slight vacuum, will neitherinfluence the mechanical paper properties in a positiveor negative way.

However, based on our modelling studies, paperdeterioration will continue and acidification will evenbe enhanced by paper encapsulation using a slightvacuum.

These results were confirmed by our studies wherepapers were stored encapsulated for 9 years.

Based on our work, encapsulation of paper using aslight vacuum is not recommended.

Finally we recommend to carry out studies of theeffects of encapsulation on alkaline and deacidifiedpapers.

5. References1. P. P. Kissing, De Armacon methoden in historisch perspectief,

Personal communication by letter, Delft, 1993.2. J. Hanus, M. Komornikova, J. Minarikova, Influence of boxing

materials on the properties of different paper items storedinside, Restaurator, 1995, 16, 194–208.


3. M. R. Brown, Polyester film encapsulation, LC Publications onConservation of Library Materials, Washington D.C., 1980.

4. E. Passaglia, The characterization of microenvironments and thedegradation of archival records: a research program, U.S.Department of Commerce, National Bureau of Standards,Institute for Materials Science and Engineering, Gaithersburg,USA, 1987.

5. S. Pauk, H. Porck, De invloed van verschillende folies enverschillende manieren van insealen op papier bij kunstmatigeveroudering, Restaurator, 1993, 23, 56–57.

6. H. Kuhn, The effect of oxygen, relative humidity andtemperature on the fading rate of watercolors. Reducedlightdamage in a nitrogen atmosphereDoerner-Institut,Munchen, Report with no date.

7. J. B. G. A. Havermans, Environmental influences on thedeterioration of paper, Barjesteh, Meeuwes & Co., Delft,Rotterdam, 1995.

8. J. B. G. A. Havermans, J. P. v. Deventer, R. van Dongen, F.Flieder, F. Daniel, P. Kolseth, T. Iversen, H. Lennholm, O.Lindqvist, A. S. Johansson, The Effects of Air Pollutants on theAccelerated Ageing of Cellulose Containing Materials – Paper.EC/DGXII/STEP Project CT 90-0100, TNO Report no. BU3.94/1068/JH, 1994.

9. ASTM, ASTM D5634-01 – Standard Guide for Selection ofPermanent and Durable Offset and Book Papers ASTM Book ofstandards 2003, 15.09.

10. ASTM, ASTM D4714-96 – Standard Test Method forDetermination of Effect of Moist Heat (50% Relative Humidityand 90°C) on Properties of Paper and Board ASTM Book ofstandards, 2001, 15.09.

11. ISO, ISO 2470 – Paper and board – Measurement of diffuseblue reflectance factor (ISO brightness), InternationalOrganisation for Standardization, Switzerland, 1977.

12. ISO, ISO 5626 – Paper – Determination of folding endurance,International Organisation for Standardization, Switzerland,1978.

13. ISO, ISO 6588 – Paper, board and pulps – Determination of pHof aqueous extracts, International Organisation forStandardization, Switzerland, 1981.

14. ISO, ISO 1924/2 – Determination of tensile properties,International Organisation for Standardization, Switzerland,1985.

15. ASTM, ASTM D 919, Copper number of paper and paperboardASTM Book of standards 1992.

16. J. B. G. A. Havermans, T. A. G. Steemers, The indoor airquality of the Dutch State Archives: its purification, qualitycontrol and safeguarding the cultural heritage, Dobbiaco,Bolzano, Italy, 25–29 June 2002 2002; Archivi SystemaArchivistico Nazionale, www.asrm.archivi.beniculturali.it/CFLR/Dobbiaco/Atti/Testi/Havermans_en.pdf.

17. R. Vosteen, Adviesrichtlijn luchtkwaliteit archieven, Ministerievan Volkshuisvesting, Ruimtelijke Ordening en Milieubeheer,Rijksgebouwendienst, 1993 (3rd edition 1995).

18. F. E. Brauns, The Chemistry of Lignin, Academic Press Inc.,New York, 1952.

19. J. Havermans, The effects of air purification on the storage ofarchival records, The Hague 2004, TNO, in print.


GRAFTING POLYMERIZATION: AN INNOVATIVE TECHNOLOGY FORPAPER CONSERVATIONElisabetta Princi*1, Silvia Vicini1, Enrico Pedemonte1, Giuseppe Ragosta2

1 Dipartimento di Chimica e Chimica Industriale, Universitŕ di Genova, Via Dodecaneso 31, 16146 Genova, Italy; 2 ICTPCNR, Via Campi Flegrei 34, 80078 Pozzuoli (Napoli), Italy* corresponding author: [email protected]

1. IntroductionNew specific polymeric materials suitable for theconservation treatment of paper have been synthesizedand tested on model paper samples obtained byaccelerated ageing.

An innovative technology based on a grafting reactionof acrylic monomers onto cellulose was invented andoptimized, with the aim to improve mechanicalproperties of degraded paper.

The effectiveness of the technology was evaluated bycharacterizing the grafted samples.

Significant paper objects of historical, artistic andarchaeological value will be conserved using thismethodology.

This study is part of “Papertech. Innovative materialsand technologies for the conservation of paper ofhistorical, artistic and archaeological value”, a researchproject, supported by the European Commission underthe 6th Framework Program, with the aim to developinnovative diagnostic techniques and protocols toevaluate the deterioration of paper and to studyinnovative materials and technologies for itsconservation.

2. Experimental Part

2.1 Materials

The cellulose substrate was Whatman paper.

Reagents were commercial products supplied byAldrich. Monomers (MMA, methyl methacrylate andEA, ethyl acrylate) contained an inhibitor (hydro-quinone monomethylether), which was removed bypassing each through an Aldrich Inhibitor Removerscolumn; the purified monomers were subsequentlystored at low temperature (4°C) and in the dark.Sodium iodate(VII) (NaIO4), acetone and methanolwere laboratory grade products from Aldrich and wereused without further purification. Deionized water wasused throughout the work.

2.2 Methods

With the intent to create photosensitive groups ontocellulose, allowing the formation of radical sites for theUV photoinduced grafting process, oxidation of paperwith iodate(VII)1 was carried. The reaction is specific inthat the C2-C3 bond of the glucosidic ring is cleaved

and the 2- and 3-hydroxyl groups are converted in twoaldehyde groups, without significant side reactions.2,3

The oxidized samples become “models” enabling us toinvestigate the different levels of degradation in realmaterials.

Therefore, the samples were treated with differentsolutions of iodate(VII) and for different times. Theratio sample/solution was kept at 1g/100 ml in allexperiments. At the end of oxidation, samples werewashed with deionized water up to neutral pH anddried.

The photo-initiated grafting reaction was carried out onartificially aged paper. Cellulose samples, after ovendrying, were swollen in deionized water for 5 min; thiswas done to open up the fibrous structure of celluloseand encourage homogeneous uptake of monomersduring grafting.4 The wet samples were placed in aquartz reaction vessel (V = 10 L), it was kept at lowpressure for a short time, so that the fabrics were stilldamp; then the liquid mixture of monomers was loaded,vaporized, and diffused into the reactor. Subsequently,at room temperature, the whole unit was exposed to UVradiation from a mercury vapor lamp (400 W, withcomplete spectrum emission from 180 nm to visiblelight), placed at 60 cm from the reactor, so that nocooling system was required. The polymerization wasstopped by pressurizing the reactor up to roomconditions. The unreacted monomer was removed bywashing the fibers with a mixture methanol-water (V/V30/70), a good solvent for acrylic monomers, but notfor the polymers. After this procedure the sample,containing grafted cellulose and homopolymer, wasfiltered and brought up to constant weight. Thedrawback of the graft polymerization is thesimultaneous and inevitable formation ofhomopolymer; it is removed from the grafted materialby extraction with acetone for 72 h at roomtemperature.5 The quantity of grafted monomer isevaluated as the weight increase of the sample afterextraction of the homopolymer:

% Grafting Yield (GY) = [(W2 – W1) x 100]/W1,

where W1 is the initial weight of the sample and W2 isthe final weight of extracted sample.

2.3 Characterization

Tensile measurements on grafted samples were per-formed on an Instron tester. Young’s Modulus (E) andelongation (e) at break were evaluated. Samples were


tested at 20 mm/min draw rate until breakage. Anaverage of 15 tests for type specimens was used tocalculate the tensile properties.

Thermal stability was evaluated by DSC analysis. DSCMettler Toledo 821e was used with oxygen flow (120cm3 min-1); the analysis was performed between roomtemperature and 650 °C at heating rate of 5 °C min-1, on5–10 mg samples in an aluminum holder.

3. Results and DiscussionGrafting polymerization was carried out by varyingsome reaction parameters: the sample oxidationconditions, the duration of polymerization, and themonomer/cellulose ratio. In Tables 1 and 2 the graftingyields with MMA and EA are reported, respectively. InMMA grafting, the ratio monomer/cellulose was fixed,whereas the oxidation conditions and the poly-merization time were varied. When grafting EA, allparameters were varied. From the data reported in theTables, it is evident that PEA (poly ethyl acrylate) leadsto a higher yield than PMMA (poly methylmethacrylate) and that higher grafting yields areobtained at higher ratios of monomer/cellulose andlonger reaction times. After about 10 h an almostcomplete conversion of the monomer is obtained andthe reaction can be considered to be complete. Graftingdoes not modify the visual aspect of the material, whichis important for objects of historical interest.

Table 1: Grafting yields for MMA on paper oxidized withNaIO4 0.1 M for 2 h. Ratio MMA/cellulose 1,5 mmol/100 g.

Polymerization time (h) Grafting Yield (%)1 112 213 324 548 86

10 89

Table 2: Grafting yields with EA on paper oxidized withNaIO4 0.1 M for 2 h. Polymerization time: 4 h.

EA/cellulose ratio (mmol/100g) Grafting Yield (%)1.5 1042 176

The stress-strain behavior of original, oxidized andgrafted paper was measured by tensile deformation; allsamples were tested to break. Young’s Modulus andelongation at break are reported in Table 3; graftingwith MMA and EA has been performed on Whatmanpaper oxidized in 0.1 M iodate(VII) for 2 h, in the samereaction conditions: polymerization time 4 h, monomer/cellulose ratio 1.5. These results indicate that in thepresence of grafted PEA the mechanical behavior ofpaper changes considerably; particularly the flexibilityof cellulose increases. This fact is due to the low glasstransition temperature of PEA (–24 °C).

Table 3: Results of tensile testing.

Sample Young’s Modulus Elongation at break(MPa) (%)

Untreated paper 1100 1.6Oxidized 0.1 M 2 h 1000 1.4Grafted PMMA 1100 1.3Grafted PEA 222 4.9

Thermal degradation of cellulose and modifiedcellulose has been extensively studied by DSC;6 itinvolves a set of concurrent and consecutive reactions.A strong exothermal peak at about 300–340 °C isattributed to cellulose depolymerization and to charringand oxidation of the decomposition products.7 A secondpeak observed above 400 °C is likely due to oxidationof the char. DSC curves of the oxidized samples showchanges in respect to the original Whatman paper. Aftereach oxidation the first peak shifts to lowertemperature, because the oxidized cellulose is alreadydegraded with a large fraction of oligomers andtherefore less energy is necessary for their thermaldecomposition. In the grafted paper, two degradationsteps concerning cellulose and acrylic polymer, areobserved and the key peak splits in two. Regardingcellulose decomposition, the peak shifts to highertemperature than the untreated paper. The shift can beexplained assuming that the grafted cellulose has abetter thermal stability due to the presence of acrylicpolymer.

4. ConclusionsThe studies reported here give an insight inunderstanding the structural changes occurring whencellulose-based materials are oxidized and grafted withacrylic polymers. Methyl methacrylate and ethylacrylate were grafted onto Whatman paper, previouslyoxidized by sodium iodate(VII), with the intent toreproduce natural oxidative ageing. Moreover, byproperly choosing the type of monomer to be grafted,the properties of the resulting copolymer can bemodulated, especially mechanical and thermalbehavior. From the point of view of the mechanicalbehavior, the results indicate that PEA can besuccessfully employed in grafting. Due to the highglass transition of the poly(methyl methacrylate)chains (105 °C), the treated samples were brittle andstiff.

The level of degradation and the effectiveness ofgrafting were evaluated using thermal analysis.

Synthesis of graft copolymers represents an interestingway to obtain composites with specific properties thatmight be also applied in the preservation of culturalheritage items of cellulosic nature. This method doesnot alter the main features of the materials and nosurface coatings are formed on the grafted samples, asdemanded by appropriate restoration practice.


5. References1. T. P. Nevell, S. H. Zeronian, Cellulose chemistry and its

applications. Halsted Press, 19852. K. Rahn, T. Heinze, Cell. Chem. Technol., 1998, 32, 173.3. U. J. Kim, S. Kuga, M. Wada, T. Okano, T. Kondo,

Biomacromolecules, 2000, 1, 488.4. S. Margutti, S. Vicini, N. Proietti, D. Capitani, G. Conio, E.

Pedemonte, A.L. Segre, Polymer, 2002, 43, 6185.5. C. E. Brockway, J. Polym. Sci. Part A, 1964, 2, 3733.6. C. Flaquč, S. Montserrat, J. Appl. Polym. Sci., 1991, 42, 3205.7. R. K. Jain, K. Lal, H. L. Bhatnagar, J. Appl. Polym. Sci., 1985,

30, 897.


THE EFFECT OF ARTIFICIAL AGING AND SIZING ONDISCOLORATION OF PAPER STUDIED BY UV-VIS-NIRSPECTROSCOPY IN COMPARISON TO ANCIENT PAPERM. Missori*1, M. Righini2, M. S. Storace1, A. Congiu Castellano3, S. Selci2

1 Istituto Centrale per la Patologia del Libro, Rome, Italy2 Istituto dei Sistemi Complessi-CNR, Rome, Italy3 Dipartimento di Fisica Università La Sapienza, Rome, Italy


1. IntroductionThe preservation of paper artefacts poses a seriousproblem for libraries, archives and museums worldwide. In order to develop appropriate conservationmethods, an advanced knowledge of the degradationprocesses which affect them is essential. Besidesdifferent paper degradation effects, discoloration andfoxing are the most obvious to the naked eye. Notwith-standing this fact, as yet almost no attention has beenpaid to the characterisation of ancient paper degradationby means of optical spectroscopy although the appli-cation of this technique provides information on paperstatus in a non-destructive way. However, an improvedcomprehension of the relation between paper structureand its optical properties, is required. In fact papersheets are complex materials consisting in a felt ofcellulose fibres (in ancient times deriving from linen) inaddition to other substances depending on the produc-tion technique employed, such as gelatine, which hasbeen used to size paper in the Western world since thebeginning of paper making history1,2. The process ofpaper degradation may be seen as a combination of acidhydrolysis, which deteriorates the mechanical pro-perties of sheets, shortening the cellulose polymericchains, and the so-called “slow-fire” caused by theoxidation of materials with subsequent development ofcarbonyl and carboxyl ligands, mechanical weakening,and discoloration of the remaining substratum3-5. On thewhole, it appears that while the overall process of paperdegradation is quite clear, it is its effect on the opticalproperties of discoloration and foxing that requiresfurther investigation.Recently we have carried out an optical reflectancespectroscopy study of ancient paper with different kindsof degradation, with either widespread discoloration orfoxing6. Paper optical response was measured in thewavelength range of 250–1100 nm. Even if thespecimens under study were of different manufacture,geographical origins, and ages, displaying a broadrange of widespread discoloration, they all show anextremely similar spectral form. A similar spectrumwas also observed by measuring foxing spots of severalintensities on a single foxed sheet. In all these samples,increasing paper degradation implies a reduction of thereflectivity in the higher energy side of the spectrum.This behaviour seems to suggest the existence of a maincause common to all samples, driving their optical

response and leaving aside other paper specimendifferences.In this contribution, in order to gain a betterunderstanding of these results, we describe our resultson the optical characterization of sized and non-sizedmodern paper samples artificially aged, and theircomparison to the ancient paper specimens. Moreover,the independent role of cellulose and sizing materialson the paper discoloration phenomena has beeninvestigated by measuring separately the modificationof their optical properties following artificial aging.

2. ExperimentalWhatman No. 1 paper samples, made of pure cellulose,were manually sized using a brush. The samples wereobtained from paper sheets acquired approximately sixyears ago and then stored at 23 °C and 50 % relativehumidity (RH). The gelatine used in sizing wasprepared following a traditional recipe for parchmentglue, as reported in the medieval manuscript entitled“De arte illuminandi”7. Modern parchment used for thispurpose was handmade by the small industry laboratoryof Otello Scaricaciottoli, Paglieta, Chieti (Italy). Anaqueous solution of gelatine at a concentration ofapproximately 3% in weight were obtained, whichachieved a dry weight uptake in the paper of approxi-mately 10%, as measured before and after the sizingprocess. Samples for gelatine transmission measure-ments were prepared by using sizing material preparedin the same way as described above. Flat surface solidgelatine film of approximately 80 µm thickness withnegligible optical scattering were produced on a quartzsubstrate. Several accelerated aging process wereperformed in a climatic chamber at constant tempera-ture and relative humidity. Three aging procedures wereused: I) 21 days at 80 °C and 65 % RH; II) 21 days at90 °C and 80 % RH; and III) 40 days at 90 °C and 80 %RH. The experimental setup used for optical reflectanceis described in ref.6. Transmittance spectra of gelatinefilms on quartz substrates were measured by a Jasco V-570 spectrophotometer by using 2 nm resolution.

3. Results and discussionIn the upper part of Fig. 1, reflectance spectra of ancientpaper samples, presenting various kinds of widespreaddiscoloration and foxing are shown. For a description of


the spectra labels see Table 1. In the lower part of thesame image the reflectance spectra of artificially agedWhatman paper samples sized with gelatine are plotted.All spectra are normalized to the reflectance ofWhatman paper No. 1. It is evident that ancient papersand artificially aged papers show a similar spectralbehaviour. This similarity is even more manifest in Fig.2 where the reflectance of a paper sample produced inFrance in 1413 (S6) and a gelatine sized aged Whatmanpaper (A4, aging procedure III) are directly comparedshowing an identical trend. This striking result makesus confident that the sample preparation protocol andthe artificial aging procedure used in this work are wellsuited for studying the discoloration processes ofancient paper. Even though the same aging procedurehas been applied to non-sized papers, none of thesesamples displayed in the measured range relevantreflectance modification. To bring attention to thisresult, the almost flat reflectance spectrum of a non-sized Whatman paper (W3) aged under procedure III isreported for comparison in Fig. 2.

The fact that the spectra of samples made by purecellulose (Whatman paper) remain constant regardlessof aging procedures, encouraged us to study the opticalresponse of collagen alone. To achieve this, weartificially aged the gelatine films deposited on quartzsubstrates by using the same protocols described before.Due to the transparency of gelatine samples, the effectof aging has been observed in transmittance.Transmittance spectra of three gelatine samples arereported in Fig. 2. It is evident that, the same spectralregion involved in the discoloration of ancient as wellas aged paper is affected by a similar variation in agedgelatine transmittance.

Studies concerning the relation between the foundchanges in spectra to molecular changes are presentlyon going. In conclusion, the independent analysis of the

aging effect on pure-cellulose and pure-gelatinesamples seems to strongly support the hypothesis thatthe main contribution on paper discoloration is due togelatine. In view of these results, it will now be aninteresting prospect to attempt to understand thegelatine aging. Similarly, the analysis of possiblecellulose-gelatine cooperative effects in discoloration ofsized paper will also be necessary.

4. References1. J. S. Dabrowski, John S.G. Simmons, Permanence of early

European hand-made papers, Fibres & Textiles in EasternEurope, 2003, 11, 8–13.

Figure 1: Reflectance spectra of ancient paper (upper part)compared to those of Whatman paper samples sized withgelatine (lower part). Curves labelled S are relative towidespread discoloured ancient specimens while the curveslabelled F have been measured on foxing spots of increasingintensity on the same ancient sample. A detailed descriptionof ancient paper samples is given in Table 1.

Figure 2: Reflectance spectra of S6 ancient paper samplecompared to those of artificially aged Whatman paper non-sized (W3) and sized with gelatine (A4) both aged usingprocedure III. In the lower part are shown the transmittancespectra of gelatine samples: G1 is not-aged, G2 and G3 areaged with procedures I and III, respectively.

0.6

0.8

300 400 500 600 700 800 900 1000

0.0

0.5

1.0

Rela

tive

Refle

ctance

Wavelength (nm)

A4S6W3

G1G2G3

Tra

nsm

ittance

0.0

0.5

1.0

Rela

tive

Refle

ctance

F1F2F3S4F4

S5S2S1S6S3

300 400 500 600 700 800 900 1000

0.0

0.5

1.0

Wavelength (nm)

A1A2A3A4

Table 1. Correspondence between the spectra labels and thesamples measured.

SpectrumLabel Sample descriptionS1 Milan, 1430, good stateS2 Milan, 1430, intermediate stateS3 Milan, 1430, bad stateS4 Nuremberg, XV century, very bad stateS5 Perpignan, 1413, good stateS6 Perpignan, 1413, intermediate stateF1 France, XVI century, area without foxingF2 same paper as F1: light foxing spotF3 same paper as F1: intermediate foxing spotF4 same paper as F1: heavy foxing spotA1 Gelatine sized Whatman paper no. 1 not agedA2 Gelatine sized Whatman paper no. 1 aged

procedure IA3 Gelatine sized Whatman paper no. 1 aged

procedure IIA4 Gelatine sized Whatman paper no. 1 aged

procedure IIIW3 Whatman paper no. 1 aged procedure IIIG1 Gelatine on quartz substrate not agedG2 Gelatine on quartz substrate aged procedure IG3 Gelatine on quartz substrate aged procedure III


2. A.-L. Dupont, The role of gelatine/alum sizing in the degradationof paper: a study by size exclusion chromatography in lithiumchloride/N,N-dimethyllacetamide using multiangle lightscattering detection, in: D. Vincent, D. Alan, P. Smith, Ed.,Works of art on paper books, documents and photographs –techniques and conservation, International Institute forConservation, Baltimore, 2002, 59–64.

3. P. Calvini, E. Franceschi, D. Palazzi, Artificially induced slow-fire in sized paper: FTIR, TG, DTA and SEM analysis, Scienceand Technology for Cultural Heritage, 1996, 5, 1–11.

4. H. Arai, Foxing caused by fungi: twenty-five years of study,International Biodeterioration & Biodegradation, 2000, 46, 181–188.

5. N. L. Rebrikova, N. V. Manturovskaya, Foxing A new approachto an old problem, Restaurator, 2000, 21, 85–100.

6. M. Missori, M. Righini, S. Selci, Optical reflectancespectroscopy of ancient papers with discoloration or foxing, Opt.Commun., 2004, 231, 99–106.

7. F. Brunello, Ed., De arte illuminandi, Neri Pozza publishing,Vicenza, Italy, 1975, 92.


IRON GALL INK CORRODED AUTOGRAPHS OF THE 18TH AND 19TH

CENTURIES

CONSERVATION OF MATERIAL CHARACTERISTICS VERSUSCONSERVATION TREATMENTSIrmhild SchäferBayerische Staatsbibliothek München, Deutschlande-mail: [email protected]

The conservation of so-called “exterior” characteristicsof documents during conservation proceduresrepresents a challenging task. The wide range ofmaterials and their different degradation states areillustrated by means of autographs of the 18th and 19th

centuries. Taking into account the modern methods ofconservation it is necessary to select optimisedprocedures for each single case of damage.

There are, basically, aqueous and non-aqueousconservation treatments available for stabilisation ofdocuments. Besides the chemical and mechanicalstabilisation of ink and paper, also other types ofinformation such as the iconic and material specifics ofdocuments (e.g. surface of paper, watermarks, color ofink, shellack and wafer seals, stamps) need to bepreserved. The method used here depends on the actualstate of damage and also on the historical type ofmaterial.

1. Aqueous conservation treatmentsBy applying aqueous methods of mechanicalstrengthening in combination with aqueous methods ofchemical stabilisation all three central conservationaims can be achieved:

1. Removal or inactivation of ferrous ions.2. Neutralisation or alkalinisation of sulphate ions.3. Strengthening of the weakened paper.

We must be aware that aqueous treatments change theoriginal composition of the inks. As a consequence,future analysis of the inks would not provide anyreliable information about the historical recipes and thecharacteristic behaviour of the aged inks.

The following aqueous treatments are used:

– Conventional treatment:An extremly thin tissue of Japanese fibres, known as“Gossamer tissue” (1,7 g/m2), is suitable formechanical strengthening of weakened paper inaqueous media. Depending on the degree of damageand the type of historical material a stronger tissueup to 5 g/m2 is required for effective stabilisation ofthe paper. However, note that thicker applicationtissue may affect transparency.

– The tissue method and leafcasting machine:A standard conservation method, applied at theInstitute of Book and Manuscript Restoration of the

Bavarian State Library (IBR) Munich, involves theuse of Japanese fibres for strengthening weakenedpaper by forming a tissue in the leafcasting machine.The tissue can be applied partially in order to keepfree unaffected areas from fibres.

– The tissue method and the use of a suction table:Sensitive objects can be strengthened by a tissue pro-duced in the leafcasting machine involving the use ofa suction table. The supporting tissue can be appliedselectively to the weakened parts of the paper.

2. Non-aqueous conservation treatmentsIn the case that aqueous treatments for the stabilisationof ink corroded papers are not suitable, we rely onalternative, non-aqueous treatments. At present, non-aqueous conservation treatments do not remove orinactivate transition metals. Therefore, the chemicalstabilisation is restricted to the neutralisation of acidsby the application of carbonised magnesium ethylate.A tissue coated with acrylate is used for the mechanicalstrengthening.

3. Concerns relating to the use of aqueoustreatments

Aqueous treatments may raise problems, because theymay effect the ink. Similarly, they may interfere withother writing fluids, the stamping-ink, the wafer andshellack seals. Furthermore the paper itself, its surfaceand dimensions as well as its watermarks need to beconsidered. In the case of progressive damage there isthe risk of worsening the degradation of the ink and thepaper. Aqueous treatments may also cause changes ofthe historical materials. Importantly, autographs of the18th and 19th centuries involve a wide range of writingmaterials. On one single document we may finddifferent kinds of ink used by the author and thecontemporary readers, and notes on envelopes in redchalk by the post office in the case of correspondence.Furthermore we may find later additional notes ofscientists as the first traces of research in directneighbourhood to stamps of the later owners of thedocuments. There are serious concerns that the differentkinds of inks and other writing fluids, pens, pencils orcrayons are not stable against “bleeding” or otherreactions caused by water. Even worse, fixatives mightbe unstable in inappropriate chemical contexts.


The texts with microscopically fine ink endlinesrepresent a valuable source of information about theindividual writing style of a historical personality. Eventiny remains of the drying sand, used by the authorimmediately after writing, may provide significantinsights into historical situations.

The seals, the fragile remains of wafers, the thin, flat,baked adhesive disks made from starch as well as thebinders and the pigments deserve special attention.Their natural fragility could lead to the completebreakage and loss. Therefore, wafers on a documentmay prevent the use of aqueous treatments.Similarly, difficulties occur with shellack seals, whichconsist of shellack dissolved in turpentine,colophonium and red pigments. Although they appearto be stable, under the microscope they often reveal alot of fine cracks. Moreover aqueous treatmentsrequire a thorough drying process. Seals need to becarefully protected during this treatment. Nevertheless,centrifugal folds, the “wrinkles”, and the tensionsaround the seals might be the side-effects of aqueoustreatments.

4. Concerns relating to the use of non-aqueoustreatments

Non-aqueous treatments need to be examined carefullyregarding the long-term behaviour of syntheticadhesives and possible changes of the optical as well ashaptical impression of the document.

5. Selection of objectsAlso here, regarding the complexity of damagingfactors and historical types of material on the one hand,and the different conservation treatments on the otherhand, we have to choose the best method for eachsingle object without affecting the iconic and materialinformation. Each case of damage requires its specificconservation treatment. Among undesirable side-effectsare not only such apparently things like bleeding of theink or increased mechanical degradation in the corrodedareas. Special attention deserve the more subtlecharacteristics of the historical materials in order tominimize the risk of affecting them during theconservation treatments.


EFFECTS OF GELATINE SIZING ON IRON GALL INK CORRODEDPAPERT. P. Nguyen*1, A. Delatour1, S. Bouvet1, V. Rouchon Quillet2

1 Bibliothèque nationale de France, Laboratoire, Bussy Saint Georges, France2 University of la Rochelle, LEMMA, La Rochelle, France

* Corresponding author :[email protected]

1. IntroductionMany types of sizing can be used in the traditionalrestoration of iron gall ink manuscripts and eachworkshop has its own practices. Up to now, gelatinesizing is not widely used in France although recentwork performed in Germany1 has shown that gelatinesizing may delay iron gall ink corrosion of paper. Themechanical tests performed on laboratory samplesshowed that gelatine can retard the loss of physicalproperties of paper containing iron gall ink duringageing. However, using this technique alone, nodistinction can be made between the effect of a gelatinereticulation and the impact of gelatine on iron gall inkcorrosion. For this reason, we tried to evaluate theimpact of gelatine as a sizing agent on the degree ofpolymerization (DP) of cellulose by using a sizeexclusion chromatography (SEC).

2. Experimental methods

2.1 Sample preparation

The paper samples were made of cotton linters,unbleached, unfilled and unsized, 80 g/m2 (provided byTNO-ref. PAPER2). The iron gall ink was composed ofFeSO4´7H2O (Aldrich 31.007-7), gallic acid (SigmaG7384) and gum arabic (Sigma G9752), molar ratio ofiron and gallic acid was 5.5:1, iron and gum arabicconcentrations were respectively 23.29 g/l and 31.4 g/l.The pieces of paper (6 × 12 cm) were immersed in afreshly prepared ink for 5 minutes. To improve thehomogeneity of the inked samples, each of them wasplaced between 2 sheets of blotting paper. The surplusink was removed by moving a metal roller usually usedto perform the Cobb test2 (20 cm wide and weighing10.0 ± 0.5 kg) once back and once forward over thepad. By using this technique, we obtained a 4%variation of iron distribution from one sample toanother and from one area to another on the samesample, instead of 30% when the roller is not used.

2.2 Artificial ageing

As C. Rémazeilles has shown that a dynamic ageingtechnique3 has the same effect on the DP of cellulose asa static one4, all the samples were aged in a climatechamber Vötsch VC 2033 at 55 °C and 75% RH. Inorder to obtain pre-degraded samples, the inkcontaining papers were pre-aged for 7 days. Then asecond ageing was carried out after conservation

treatments of the pre-aged samples. After 5, 12 and 17days, series of samples were removed from the oven foranalysis.

2.3 Conservation treatments

In order to study the effect of gelatine sizing (220Bloom) on inked paper, different methods ofapplication were compared: 5 min. immersion in water,5 min. immersion in a 1% gelatine solution, sprayingwith a 1% gelatine solution, coating with a 10%gelatine solution using a brush. The first two treatmentswere used to evaluate the migration of iron ions in thesolution during immersion. The last two treatmentswere used to compare the effect of concentration ofgelatine on cellulose. No significant change in thecontent of iron ions due to conservation treatment isexpected in these two samples.

2.4 Size exclusion chromatography

The DP of ink containing paper was analysed using theSEC technique. The procedure for samples preparationand chromatographic conditions were the same asdescribed by Heike Jerosch5, except for the columnswhich were three Phenogel GPC, 5 mm, mixed bed,300 × 7.8 mm plus a Phenogel GPC, 5 mm, mixed bed,50 × 7.8 mm.

Before the swelling step, the gelatine containingsamples were soaked 2 times in hot water (70 °C) inorder to remove the gelatine sizing as much as possible.

2.5 Iron content determination

The content of total iron in the laboratory samples wasdetermined by spectrophotometry usingbathophenanthrolinedisulfonic acid as a colour reagent.36 cm2 of inked paper was placed in a crucible thenincinerated at 570 °C. After complete cooling, 3 ml of6N HCl was added and heated 5 min. at 150 °C. Thissolution was diluted to 50 ml with deionized water then10 ml were taken and placed in a 25 ml volumetricflask. 7.5 ml of 100% acetic acid adjusted to pH 4.7,500 ml of a 20 g/l hydroxylamine hydrochloridesolution (Acros Organics 5471-11-1), 500 ml of a 5 g/lbathophenanthrolindisulfonic acid disodium saltsolution (Sigma B1375) were added in this order andthe mixture was brought up to 25 mL with water.Hydroxylamine hydrochloride was used to reduce theFe(III) in Fe(II) which forms a deep pink coloured


complex with bathophenanthrolin. The total ironconcentration was determined using a Perkin ElmerLambda40 spectrophotometer settled at 156 nm. Thecalibration was performed by adding 1.25, 2.5, 3.75 and5 ml of a 0.01 N Fe(SO4)´7H2O solution to the 25 mlflask.

3. Results and discussion

3.1 Iron migration during immersion

Before and after treatment, each laboratory sample wasincinerated for total iron quantification. Before anytreatment, the quantity of iron measured in all the 15inked samples was 12 ± 0.5 mg/cm2. This quantity isequivalent to the average one measured in a previousstudy by C. Rémazeilles on 50 historical manuscripts(dated from 1826 to 1842) containing iron gall ink,using PIXE analysis.

After conservation treatments (3 samples were analysedper treatment), as shown on figure 1, the same quantity,about 25% of original iron content, was removed fromthe inked papers during immersion treatment in wateror in 1% gelatine solution. As expected, no iron ionswere washed out after spraying and coating treatments.

the conservation treatments is observed. It is also notpossible to make a distinction between the washingeffect and the effect due to the presence of gelatine.Nevertheless, we can notice that the treated samples’molecular mass remains quite stable during the five firstdays of artificial ageing; so the conservation treatmentscould have some positive short-term effect on inkedpapers, although additional work is needed to confirmthis observation.

Surprisingly, it is remarkable that even when a signifi-cant quantity of iron ions is washed out after immersion(25%), the depolymerisation of the cellulose is notreduced more than 15% compared to the reference.

0

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8

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14

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immersed in1% gelatin

sprayed with1% gelatin

coated with10% gelatin

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Figure 1: Iron content in pre-aged inked samples afterconservation treatments. Error bars represent standarddeviations.

3.2 Effects of conservation treatments on the DPof the cellulose

The evolution of the weight average molecular massMw versus artificial ageing is plotted on figure 2 fortreated and non-treated samples. This graph shows thatthe Mw values are similar for non aged papers beforeand after gelatine sizing, confirming the fact that thegelatine does not disturb the SEC analysis of cellulose.

Looking at the evolution of Mw versus artificial ageing,compared to the reference, no clear long term effect of

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Ageing time (days)

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reference (untreated)immersed in waterimmersed in 1% gelatinsprayed with 1% gelatincoated with 10% gelatin

Figure 2: Changes of the Mw of treated inked paperscellulose during artificial ageing at 55 °C and 75% RH.R.S.D. is 5%.

4. ConclusionIn the light of the results obtained by SEC, it appearsthat neither water immersion nor gelatine sizing haveany significant effect on ageing stability of iron gall inkcontaining paper. Gelatine may however still affect therate of diffusion of the ink or its components duringaquous treatments, as suggested by Gelsa Kolbe6.

5. References1. G. Banik, G. Kolbe, J. Wouters, analytical procedure to evaluate

conservation treatments of iron gall ink corrosion, 4èmesjournées internationales d’études de l’ARSAG, Paris,m 2002,205-217.

2. Tappi test method T441 om-90.3. C. Rémazeilles, internal paper, CRCDG, post Doc. report, 2002.4. J. G. Neevel, Phytate: a potential conservation agent for the

treatment of ink corrosion caused by iron gall inks, Restaurator,1995, 16, 143-160.

5. H. Jerosch, B. Lavédrine, J. C. Cherton, Study on the correlationbetween SEC and mechanical tests of different paper types fordegradation state evaluation, Restaurator, 2002, 23, 222-239.

6. G. Kolbe, Gelatine in historical paper production and as ainhibiting agent for iron gall ink corrosion on paper, Restaurator,2004, 16, 26-39.


EVALUATION OF RELATIVE FE2+ AND FE3+ CONTENTS OF ORIGINALMANUSCRIPT FRAGMENTS BY MEANS OF µ-XANES ANDMÖSSBAUER SPECTROMETRYK. Janssens*1, V. Rouchon-Quillet2, C. Remazeilles3, M. Eveno4 and A. Wattiaux5

1 Dept. of Chemistry, University of Antwerp, Antwerp, Belgium2 CRCDG, Paris, France3 LEMMA, La Rochelle University, La Rochelle, France4 Bibliothèque Nationale de France, Paris, France5 ICMCB, Pessac, France

* [email protected]

1. IntroductionThe corrosion of paper due to iron gall ink is generallyattributed to a combination of two mechanisms : acidhydrolysis and oxidation enhanced by the presence offree Fe2+. The presence of free Fe2+ and free Fe3+ inoriginal samples can easily be detected with a spotcolour test. Yet this detection remains qualitative, andlittle information is available on the quantity of Fe2+ andFe3+ present in the original inks.

In this work, an attempt was made to estimate the Fe2+/Fe3+ content in a set of original manuscripts usinginstrumental techniques µ-XANES and Mössbauerspectrometry These manuscripts consisted of valuelessdocuments in variable states of preservation: some werein a perfect condition, whereas others were highlydamaged. Particular attention was paid to a samplefeaturing white crystal-like precipitates within the inkcontaining areas of the paper.

Microscopic X-ray absorption near-edge spectroscopy(µ-XANES) measurements were performed with alateral resolution of 30-50 µm in order to determine thelocal Fe2+/Fe3+ ratio. For comparison, an averageestimation of the Fe2+/Fe3+ ratio was also obtained bymeans of Mössbauer spectrometry on two suitablesamples (sample M and C) for which great quantities ofdark-coloured damaged material were available.

2. Experimental

2.1 µ-XANES experiment

The XANES experiments were carried out at beam-lineL of HASYLAB (Hamburg, Germany)1. By varying theenergy of the primary X-ray beam in small (typically 1eV) steps across the K-absorption edge of Fe. In aprevious study, the XANES profiles recorded fromhand written characters in a 16th century prayer bookcould be well described as a linear combination of thereference profiles FeSO4.7H2O and Fe2(SO4)3.5H2O,allowing to estimate the relative abundances of Fe2+ andFe3+, as was confirmed by cross-validation withMössbauer spectroscopy2. In the present work, only in alimited number of cases, this simple regression modelwas found to be sufficient to adequately describe the

experimental XANES profiles. Since it can be expectedthat Fe in aged iron gall ink is present as a verycomplex mixture of different compounds, it is ratherdifficult to make a quite rigorous description of theXANES profiles. The numbers cited below, which wereobtained on the simple sulphate model, can only beregarded as preliminary and semi-quantitative.

2.2 Mössbauer experiment

Mössbauer measurements were performed at roomtemperature using a constant acceleration HALDERtype spectrometer, with a 57Co source (Rh matrix) intransmission geometry. The spectra were recorded at293 K. It was necessary to perform the measurementson a stack of approximately 10 sheets together to enablerecording of spectra in a reasonable timescale of twoweeks. Moreover, for such sample preparation linebroadening effects can be neglected. The velocity wascalibrated using pure iron metal as reference material.The experimental data were resolved into symmetricdoublets with Lorentzian lineshapes using an iterativeleast-squares fit program. When the refinement of theMössbauer spectra showed an important and abnormalwidening of the peaks, the spectra were fitted assuminga quadrupolar splittings distribution3.

2.3 Examined documents

The historical samples examined in this study wereclassified according to the four-level system developedby Reissland4. Seventeen samples were examined; fourof these were in an advanced state of degradation (type4) while the majority was in a better condition (types 2and 3). Some samples, though originating from thesame sheet of paper, had a totally different outlook andwere classified in different categories. With theexception of two samples dating from the middle of the18th century, all the selected samples had the sameorigin: they were written between 1826 and 1842,consisted of handmade paper with a similar filigree andwere stored together in identical conditions during thesame period of time. They show neither water norbacteriological damage. An elaborate description ofthese samples can be found elsewhere5. In particular,


PIXE elemental measurements were performed on thesesamples, showing various iron contents ranging 1016 to1018at/cm2.

3. ResultsFor all the samples except sample M, XANES examina-tion of the inked areas pointed out a Fe2+-abundanceconsistently lower than 10–15%. Unfortunately, thesensitivity of XANES technique to low Fe2+ content israther poor, and further methodological development isrequired in order to evaluate more accurately theFe2+/Fe3+ ratio. However, XANES measurementsperformed on sample C are consistent with a Mössbauermeasurement estimating the Fe2+ abundance to be in the11–15% range.

The case of sample M is quite different from the others.It has the highest iron content (2.1018 at/cm2 to 5.1018

at/cm2 ). The semi-quantitative XANES measurementsperformed on different parts of this sample aresummarized Table 1. Whereas Mössbauer spectrometryperformed on dark-coloured completely damagedfragments, indicates that, on average, up to 90% of thetotal iron correspond to Fe2+, quite variable results areobtained using of µ-XANES, depending on the areawhere the measurements were carried out. The whitecrystal-like precipitates, which can be observed onsome of the inked areas (see Fig. 1a), on average showabout twice as much Fe atoms per unit area than thesurrounding black ink (see Fig. 1b). Although it was notpossible to obtain XANES data from the precipitatesseparately, on average the ‘crystals’ appear to containsignificantly less Fe2+ than the surrounding inked areas(see Fig. 1c).

Table 1: Semi-quantitative estimation of Fe2+/Fe3+ (%) insample M using µ-XANES.

Area Number of Fe2+/Fe3+ (%)measurements

Paper in good condition 3 10 to 30Brown halo around characters 2 35 to 40Ink 9 35 to 70White crystals on ink 6 20 to 50

Micro-Raman spectrometry was used to identifysulphate (SO4

2-) as the major anion present in theprecipitates; however, the vibration mode signatureshows similarities to but is not identical to that of eitherFeSO4´7H2O or Fe2(SO4)3´5H2O.

4. ConclusionThis preliminary work shows that XANES andMössbauer measurements performed on two originalsamples were rather consistent with each other.

However, it appears rather difficult to fit some of theexperimental XANES data using the simple sulphatemodel. This confirms that the iron present inmanuscripts has various chemical environments whichare more complex than a mixture of FeSO4´7H2O andFe2(SO4)3´5H2O. Thus, more attention should be paid tothe selection of references in order to improve theprecision of the measurements.

Great care should also be taken when choosing the area,which is relevant to the average ink composition.Indeed, the observations made on sample M, show greatvariations of the Fe2+/Fe3+ ratio even in a small arearanging approximately 1 mm2. These variations wererelated to the presence of crystal-like aggregates on thesurface of the ink.

5. References1. K. Proost, L. Vincze, K. Janssens, N. Gao, E. Bulska, M.

Schreiner and G. Falkenberg, Characterization of a polycapillarylens for use in micro-XANES experiments, X-ray Spectrometry,2003, 32, 215–222.

2. K. Proost, K. Janssens, B. Wagner, E. Bulska and M. Schreiner,Determination of localized Fe2+/Fe3+ ratios in inks of historicdocuments by means of µ-XANES, Nuclear Instruments andMethods in Physics Research B, 2004, 213, 723–728.

3. J. Hesse, A. Rubartsch, J. Phys. E. Sci. Instrum, 1974, 7, 526.4. B. Reissland, J. Hofenk de Graaff, Condition rating for paper

objects with iron-gall ink. In: ICN-Information nr. 1.5. C. Rémazeilles, Etude des processus de dégradation des

manuscrits anciens écrits à l’encre ferrogallique : analysed’échantillons originaux et d’éprouvettes de laboratoire, mise enévidence du rôle de l’acide gallique et de la gomme arabique.Rapport de thèse de doctorat, Université de La Rochelle (2001).

Figure 1: Optical photograph (a), total Fe distribution (b) andFe chemical state map (c) within a character “a” on afragment of sample M. Area shown: 2.4 x 3 mm. In (b)darker colours indicate higher Fe levels; in (c) darker greyindicated a lower Fe2+ content.


THE IMPACT OF GUM ARABIC ON IRON GALL INK CORROSIONVéronique Rouchon Quillet*1, Céline Remazeilles2, Thi Phuong Nguyen3, Jean Bleton4, Alain Tchapla4

1 CRCDG, Paris, France2 LEMMA, La Rochelle University, France3 BNF, Bussy Saint Georges, France4 LETIAM, Orsay University, France


1. IntroductionIn the occidental world, gum arabic has beenextensively used as a binder in iron gall ink preparation,but its influence on iron gall ink corrosion has not beenextensively studied. In this work, we investigate theimpact of gum arabic on iron gall ink corrosion usinglaboratory samples made of cotton linters cellulosepaper with no additives. This paper was impregnatedwith different solutions combining the three mainingredients of iron gall ink, namely, gallic acid, ferroussulphate and gum arabic. The paper degradation versusartificial ageing was evaluated using bursting strengthdeterminations, FTIR spectrometry, and size exclusionchromatography (SEC). The degradation of the gumitself was evaluated using gas chromatography/massspectrometry (GC/MS).

2. Experimental

2.1 Materials and solutions

The composition of selected paper samples was veryclose to that of pure cellulose: most of the samples wereTNO cotton linters cellulose paper. Only for SEC,Whatman paper was used.

The ink ingredients were all laboratory grade (table 1).Only freshly prepared solutions were used. In order toevaluate the influence of gum arabic, we prepared twoseries of samples, the first one with a mixture of ironsulphate and gallic acid called “Fe+Ac”, and the secondone with a mixture of iron sulphate, gallic acid, andgum arabic, called “Fe+Ac+Gu”. The molar ironsulphate to gallic acid ratio was chosen to be 5.5regarding previous work performed by Han Neevel1.

Table 1: Chemicals used for preparation of the inks.

Iron sulphate Gallic acid Gum ArabicSEC measurementsReference of ALDRICH SIGMA SIGMAthe product 31,007-7 G7384 G9752

CAS 7782-63-0 CAS 149-91-7 CAS 9-01-5Concentration 6,95 0,77 31,40used (g/L)Other measurementsReference of ALDRICH ALDRICH ALDRICHthe product 21,542-2 39,822-5 n°26,077-0

CAS 7782-63-0 CAS 5995-86-8 CAS 9-01-5Concentration 5,69 0,70 31,40used (g/L)

2.2 Preparation of the samples

For mechanical measurements, inks were applied on thepaper in square patterns about 1 centimetre wide usinga computer guided plotter pen (Phillips Digital PlotterPM 1855), with a 0.5mm point. For the other samples,the paper was simply soaked in the respective solutionsfor approximately 10 s and dried in an ambientatmosphere. The iron concentration per surface unit isconsidered to be homogeneous within ± 25%. Thequantity of iron deposited on TNO cotton linterscellulose papers was determined in the centre of thesamples using atomic absorption spectroscopy (13 mg/cm2 ± 5 %). The average quantity of iron deposited onWhatman papers was measured by spectrophotometry2

using bathophenanthroline disulfonic acid as a colourreagent (37 mg/cm2 ± 5 %).

Most of the samples were artificially aged in a Vötsch0020 oven at 90 °C and the relative humidityfluctuating every 3 hours between 80% and 35%. Onlysamples prepared for SEC measurements wereartificially aged using a lower temperature (71 °C) anda constant relative humidity (75%).

2.3 Apparatus

The loss of mechanical properties during artificialageing was determined using a normalized burstingtester (Adamel-Lhomargy EC 05).

FTIR measurements were performed on a Paragon 1000PC spectrometer provided by Perkin Elmer. Theartificially aged papers were grounded by hand withpotassium bromide (KBr) in an agate mortar.Measurements were carried out on the resulting powderusing the diffuse reflectance mode3.

SEC measurements were performed at the sameconditions as those described by Heike Jerosch4 exceptfor the columns (three Phenogel GPC, 5 mm, mixedbed, 300 × 7,8 mm, with a Phenogel GPC, 5 mm,mixed bed, 50 × 7,8 mm).

The GC/MS measurements were carried out on aHP5890 chromatograph (Hewlett Packard) interfacedby direct coupling to an INCOS 50 quadrupole massspectrometer (Finnigan). The experimental conditions,including preparation of samples have been depictedpreviously5.


3. Results3.1 Mechanical properties

Figure 1 reports the loss of mechanical propertiesversus artificial ageing at 90 °C. The bursting strengthvalues measured on non-aged samples are similar tothat of virgin paper. During artificial ageing, the paperbecomes locally more brittle and breaks along the inkpatterns. After 3 days of artificial ageing, one canobserve that the “Fe+Ac+Gu” samples are moreresistant than the “Fe+Ac” samples. Yet, all sampleswere rapidly degraded, and after 7 days of artificialageing, no differences can be measured, mainly becauseof the large scatter of the results obtained by thebursting tester.

pH determinations were carried out with a flat-surfaceelectrode on the samples which were aged at 90 °C. Thetwo series of samples have similar pH values (3.5 ±0.5) and, these values seem to be constant during the 42days of artificial ageing. using lower temperature of 71 °C of artificial ageing

and SEC analysis to measure the changes of Mw ofcellulose. The evolution of Mw versus time of artificialageing (figure 3), confirms clearly the positiveinfluence of gum, which reduces the rate of degradationof cellulose.

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Figure 1: Evolution of bursting strength versus artificialageing (T = 90°C, RH = 35–80%) for TNO cotton linterscellulose paper impregnated with two different solutionscombining iron sulphate (Fe), gallic acid (Ac) and GumArabic (Gu).

3.2 FTIR measurements

The sensitivity of the FTIR technique is rather poor.Also, on non-aged samples, the presence of gallic acid,and/or gum arabic on the paper induces absolutely nochange in the FTIR spectra, which is quite similar to thecellulose absorption spectrum. These components arefar too diluted in the cellulose to be detected. One hasto go very far in the paper degradation process toobserve some changes in the FTIR signal. Thesechanges are limited to the region 1700 cm-1 to 1800cm-1 which is characteristic carbonyl groups stretchingvibration (see figure 2). We are inclined to think thatthese changes are mainly due to the paper itself, and notto the additives. Figure 2 shows that, in the presence ofgum, alkene and carbonyl groups are less numerous inthe degraded cellulose.

3.3 Size Exclusion Chromatography

In order to evaluate the influence of gum moreaccurately, we undertook a second set of experiments

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3.4 Gas Chromatography

In order to evaluate the stability of gum arabic duringageing, we mixed pure gum arabic with ferroussulphate powder and put the mixture in the climaticchamber for artificial ageing at 90 °C with the relativehumidity fluctuating every 3 hours between 80% and35%. Within a few days, the colour of the mixtureturned dark brown, whereas the colour of gum alone,artificially aged at the same conditions, was still verylight. GC/MS measurements confirm this observation:no significant changes are observed on thechromatograms when gum arabic is aged alone, whiledrastic changes are observed when it is mixed withferrous sulphate. The intensity of signal of arabinose,

Figure 3: Decrease of cellulose molecular weight versus timeof artificial ageing (T = 71 °C, RH = 75%) for Whatmanpaper impregnated with two different solutions combiningiron sulphate (Fe), gallic acid (Ac) and gum arabic (Gu).


and rhamnose decreases, and some galactonic acidappears. This proves that gum Arabic degrades veryfast in the presence of iron. Its positive influence oniron gall ink corrosion is also limited in time.

4. ConclusionResearch presented demonstrates that, when gum arabicis added to the ink, the degradation of the paper isdelayed. We are inclined to believe that this effect ismainly due to physical factors, as the gum coats thepaper fibres, and thus limits the diffusion of oxygen orfree iron. This protective effect is limited in timebecause the gum is itself very sensitive to iron sulphate.

5. References1. J. G. Neevel, Phytate: a potential conservation agent for the

treatment of ink corrosion caused by iron gall inks, Restaurator,1995, 16, 143–160.

2. T. P. Nguyen, A. Delatour, S. Bouvet, V. Rouchon Quillet, Effectof gelatin sizing on iron gall ink corroded paper, Durability ofPaper and writing, Lubjana, 2004, Nov. 16–20th, proceeding.

3. C. Remazeilles, PhD thesis, University of La Rochelle, 2001 July18th.

4. H. Jerosch, B. Lavedrine, J.C. Cherton, Study on the correlationbetween SEC and mechanical tests of different paper types fordegradation state evaluation, Restaurator, 2002, 23, 222–239.

5. J. Bleton, P. Mejanelle, J. Sansoulet, S. Goursaud, A. Tchapla,Characterisation of neutral sugars and uronic acids aftermethanolysis and trimethylsilylation for recognition of plantGums, Journal of Chromatography A, 1996, 720, 27–49.


LASER CLEANING OF PAPER – A STEP TOWARDS OPTIMISATIONV. S. Šelih*1, M. Strlič1, J. Kolar2, D. Kočar1, B. Pihlar1

1 University of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5, 1000 Ljubljana, Slovenia2 National and University Library, Turjaška 1, 1000 Ljubljana, Slovenia


1. IntroductionIn conservation, laser cleaning is becoming more andmore popular. Commercial laser cleaning systems havebecome available during the last years and are nowbeing increasingly used in conservation studios acrossEurope, where well over 20 such systems are availabletoday.1

variety of applications.3 Interactions between thesubstrate and laser light may be such that bothformation of new chromophores (discolouration oryellowing) and destruction of already existingchromophores (bleaching) may occur simultaneously4,5,especially if the substrate is a complex material, e.g.lignin-containing or gelatine-sized paper. Yellowing isa common phenomenon observed when fibrousmaterials are cleaned using ordinary laser cleaningparameters (Nd:YAG – 1064 nm or 532 nm; 0.1-1J/cm2, repetition rate 10-50 Hz, 5-10 ns pulse duration).Formation of chromophores during dry laser cleaningof paper is not a sufficiently understood phenomenonand a higher level of knowledge could lead to betteroptimised cleaning parameters, thus reducingundesirable side effects. This was the scope of ourwork.

2. ExperimentalPurified cotton linters cellulose paper (Whatman N° 1filter paper) was used as a model. To obtain anexaggerated soiled model, well defined charcoalpowder (low content of impurities, uniform particlesize) was used as model soiling in high surface density.It was deposited onto paper by filtering aqueoussuspension through paper sheets. Viscometry accordingto standard procedure,6 using freshcupriethylenediamine solvent was used to determine thedegree of polymerisation (DP)7. Accelerated lightageing studies were performed in Xenotest Alpha lightageing chambers. Accelerated thermal ageing (up to160 h, 90 °C, 65% RH) was performed in a VötschVC0020 climatic chamber. Chemiluminescenceexperiments in N2 atmosphere were performed withLumipol 2 instrument. Colorimetric measurements ofsamples were performed with a Minolta CM-3610ddiffuse reflectance VIS spectrophotometer with thespecular component excluded. The reflectance wasmeasured in % relative to polymeric Minolta standard.CIE L*a*b* system8 was used to evaluate the colourchanges.

Two Q-switched Nd-YAG lasers at fundamental(1064 nm) or doubled frequency (532 nm) were usedin this study. Soiled samples used forchemiluminometric analyses and study of light ageingstability were treated with 1 J/cm2 fluence and 8 mmspot diameter laser pulse. For optimisation of cleaningprocess other laser with lower fluences (0.05 and 0.1J/cm2), 5 mm spot and 1 and 10 shots per secondrepetition rates was used.

Figure 1: Example of laser cleaning of a paper document.

Laser-based cleaning is a well controllable method forremoval of soiling from the surface of a substrate.2 It isfurthermore highly selective, contact- and reagent-less.In many cases it gives the conservator a level of controlnot achievable with the traditional cleaning methods.Two general approaches to laser cleaning are used; dryand wet (water assisted) approach. While in the case ofdry laser cleaning only interaction of light with soilingleads to a cleaning effect, wet laser cleaning takesadvantage of interaction of laser light with waterdeposited on soiling. For paper, dry laser cleaning isused.

During laser cleaning, removal of soiling should inprinciple proceed without alterations of the underlyingsubstrate of an artefact. This is possible only if lightabsorptivity of soiling is considerably higher than thatof the substrate and if there is no interaction betweensoiling particles and the substrate. In case of sensitiveorganic materials, e.g. paper, parchment and textiles,this is frequently not the case and surface modificationafter laser cleaning may be observed, exhibited asdiscolouration or yellowing.

Yellowing as a result of laser cleaning is a particularlydisturbing phenomenon and it has been noticed in a


3. Results and discussionWith chemiluminometry we showed, contrary toRudolph et al.,9 that changes in substrate immediatelyafter laser treatment can be observed. In a dynamicexperiment, chemiluminescence activity of samplesimmediately after laser treatment is evident already atlow (<100 °C) temperatures. This indicates thepresence of reactive species, formed during the processof laser cleaning and gradually decomposed, as can beseen in Fig. 2, curves a, b, c. It is evident that thespecies is quite long lived in darkness at roomconditions (22 °C), but is easily destroyed by oxidation(Fig 2, curve d). as a consequence, limitedchemiluminescence emission, close to background, isobserved at low temperatures (<100 oC).

thermal ageing experiments all support the fact thatchemical changes do take place and will in long termdestabilize structural integrity of the substrate. Light-induced ageing processes are of particular importancefor objects which are exhibited after laser cleaning.

The data in Figure 3 demonstrate that as a result of lasercleaning, the yellow component b* increasessubstantially. However, extensive bleaching ofchromophores takes place even during irradiation withλ>340 nm, the difference amounting to 7 units in 7days. Long-term instability towards chain-scission,however, is also impaired and the laser-treated materialdegrades more quickly than the original non-treatedone. Similar results can be demonstrated for thermalageing.

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Figure 2: Chemiluminescence emission in nitrogenatmosphere during dynamic experiments (temperaturegradient: 2.5 °C/min) after a 15-min period of flushing, bothin N2 atmosphere. All samples were soiled and laser-cleaned(Nd:YAG 1064 nm, 1 J/cm2) and stored in darkness for: a) 20min; b) 22 h; a) 95 h. Sample d) was, 98 min after thecleaning, oxidized in O2 at 100 °C for 30 min and thensubjected to the same chemiluminometric experiment.

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Figure 3: Changes in b* and DP during photo ageing(l>340 nm) of a non-treated and a soiled and laser-cleaned(Nd:YAG 1064 nm, 1 J/cm2) cellulose sheet.

Results, obtained with size exclusion chromatography,chemiluminometry, FTIR, accelerated photo and

The rate of thermal degradation at 80 oC, 65% RH isalso significantly changed – it is evident that thestability of laser-cleaned paper will be impaired in thelong term.

It was already shown9,10 that laser cleaning at 532 nmmay in several cases be preferable to 1064 nm, and thatone pulse of 1 J/cm2 is better than several pulses oflower fluence4. Considering that cellulose is a thermalinsulator, the heat generated during interaction of lightwith particles of soiling, is accumulated in the treatedarea.

4. ConclusionsDue to differences in type of soiling and type of paperitself, universal conditions for laser cleaning can not beput forward.

The research results obtained with an exaggeratedmodel (high surface density of charcoal soiling, highlysensitive cellulosic material), indicate that lasercleaning of paper may result in its increased instability.

However, it should be stressed that even if optimal lasercleaning conditions are achievable, with minimalyellowing, the cellulosic substrate will still be

Figure 4: Degree of polymerisation during acceleratedageing (80 oC, 65% RH) of a non-treated and a soiled andlaser-cleaned (Nd:YAG 1064 nm, 1 J cm-2) cellulose sheet.

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destabilized in the long-term, both during thermal andphoto ageing. It is doubtful whether large-areaapplications are thus acceptable, while laser cleaning oflocalised areas may still be the cleaning method ofchoice in certain instances (low mechanical stability,hindered access, unavailability of other treatments).Furthermore, since paper is a complex material, thebehaviour of a particular artefact during laser cleaningis difficult to predict, and testing before use is essential.

5. References1. Artwork conservation by laser in Europe database http://

alpha1.infim.ro/cost/pagini/TEXT-BD.htm2. S. Georgiou, Adv. Polym. Sci., 2004, 168, 1–49.

3. V. Verges-Belmin, C. Dignard, Journal of Cultural Heriatage,2003, 4, S238–S244

4. M. Strlič, J. Kolar, V.-S. Šelih, M. Marinček, Appl. Surf. Sci.,2003, 207, 236–245.

5. V. R. Botaro, C.G. dos Sanots, G. Arantes Junior, A. R. daCosta, Appl. Surf. Sci., 2001, 183, 120–125.

6. SCAN-CM 15:88: Viscosity in Cupri-Ethylenediamine Solution,Scandinavian pulp, paper and board testing committee, 1988, 1–7.

7. R. Evans, A. F. A. Wallis, 4th Int. Symp. Wood Chem. 1987,201–205.

8. K. McLaren, JSDC, 1976, 338–341.9. P. Rudolph, F. Ligterink, J. L. Pedersoli Jr., M. Van Bommel, J.

Bos, H. A. Aziz, J. B. G. A. Havermans, H. Scholten, D.Schipper, W. Kautek, Appl.Phys.A, 2004, 79, 941–944.

10. J. Kolar, M. Strlič, S. Pentzien, W. Kautek, Appl. Phys. A,2000, 71, 87–90.


COMPARISON BETWEEN STARCH AND METHIL CELLULOSESURFACE COATING DURING THE LEAF CASTING TECHNIQUEJedert Vodopivec*1, Stanka Grkman1, Meta Černič-Letnar2

1 Archives of the Republic of Slovenia, Ljubljana, Slovenia2 Pulp and Paper Institute – ICP, Ljubljana, Slovenia


1. IntroductionStarch1 and water-soluble cellulose ethers2, areimportant additives in paper production, in papersurface sizing and coating. They are as well used inpaper conservation as adhesives, paper coatings orstrengtheners, consolidates and also as cleaners.3 Aresearch into the influence of starch and cellulose ethersurface coating on the properties of paper formedduring conservation by leaf casting was conductedwithin the framework of the applied research project4

“Optimization of conservation leaf casting technique”.In this context the first part of individual properties ofstarch types and starch layers were studied anddetermined. After having compared the results, we wereable to confirm the assumption that starch propertiesdepend mostly on its origin (wheat, potato, corn). Thispart was presented at the ICOM-CC meeting inLjubljana on March 2004.5

2. Experimental partIn the next stage of the mentioned research project,paper samples were prepared in the same manner andwith the same fibre composition as for the first part, theonly difference was the coating where somemethylcelluloses were applied and tested. Some typicalphysical properties of the tested samples weredetermined, and comparison with the results obtainedwith starch surface coated samples was performed. Inthe presentation the results of the comparison betweenstarch and methylcellulose surface coatings appliedduring the leaf casting conservation technique, arepresented. Due to financial restrictions only twosamples of methylcellulose coating were possible toanalyse. We selected one of the most frequently usedproducts in paper conservation, a relatively low andmedium viscosity was selected. The following samplesof starches and MC were used:

Sample 1: Sudsterke potato starch (Helios),Sample 2: Cerestar wheat starch , (Helios),Sample 3: Cerestar corn starch (Helios),Sample 4: Papiran SKM-42 corn cationic active starch

(Helios),Sample 5: Drei hasen Weizenstarke wheat starch

(Laursen),Sample 6: Jin Shofu Japanese wheat starch,Sample 7: CULMINAL MC 2000 (Hercules),Sample 8: CULMINAL MC 7000 (Hercules).

Measurements and analysis of surface coated papersamples were conducted at the Pulp and Paper Institutein Ljubljana, according to ISO and TAPPI standardsand ICP methods:

– Basic physical-structural properties (grammage6,thickness, density, specific volume7, uniformity of thepaper sheet – M/K-3D formation index8).

– Mechanical properties (tearing resistance9, burstingstrength10, folding endurance – MIT11, stiffness –Clark12)

– Surface properties (smoothness – Bekk13, porosity –Gurley14, contact angle – FibroDAT15).

– Optical properties (ISO brightness16, opacity17, lightscattering and light absorption18).

3. Results and Discussion1. Starches and MC surface coatings on paper influence

only the paper uniformity, which is shown asimprovement of the formation index. Other basicphysical structural properties were not affected.

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Figure 1: The effect of starch and MC surface coatings onthe uniformity of paper samples.

2. Mechanical properties in general did not improvemuch with starch and MC, except the foldingendurance. Starch samples showed less improvedvalues. A distinct improvement in double folds wasobserved with 1% potato starch (sample 1).

The best results were obtained with samples coatedwith Culminal 7000 0,5% and Culminal 2000 1%.(fig. 2)

3. Measurements show that starch or MC surfacecoatings do not affect smoothness, but only porosityand hydrophilic properties. Results show that 1%


concentrations of potato (sample 1), corn (sample 3),Japanese wheat starch (sample 6), Culminal 2000(sample 7) as well as 1% Culminal 7000 (sample 8)reduce porosity of paper structure. (Fig. 3)

4. In general application of starch and MC does notaffect measured ISO properties. We noticed onlysome reduced values in opacity, which means highertransparency, on samples coated with 1% potatostarch (Sample 1) and with 0,5% Culminal 7000(Sample 8), all the others samples show no change inopacity.

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Figure 2: The effect of starch and MC surface coatings onpaper samples tested for folding endurance.

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Figure 3: The effect of starch and MC surface coatings onthe porosity of the paper samples.

Application of starch and MC on the surface of paperslightly decreases its hydrophilic properties. Thesurface becomes less wet absorbent, but still remainshydrophilic. The best results were obtained with 0,5% Culminal 2000 (Sample 7). (Fig. 4)

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Figure 4: The effect of starch and MC surface coatings onthe hydrophilic/hydrophobic properties of the paper samplesmeasured with contact angle – FibroDAT.

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4. ConclusionsWith the comparison of analysed properties ofleafcasted coated paper samples we examined the effectof starches and methylcellulose surface coatings onsome typical physical properties used in paper testing.From the results conducted during the research we maybe able to conclude that:

– Not all starches are suitable for surface coatingapplication in the paper conservation leafcastingprocedure.

– Potato starch coating (sample 1) show improvedproperties, but because of its great adhesion it is notadequate as coating during the leafcasting.

– Corn starches coatings (Sample 3 and 4) show noimprovement on treated paper samples.

– Wheat starches (Samples 2, 5 and 6) show the bestresults among analysed starches.

– Starch and MC coatings improve paper formation.– MC, compared to starches improves some surface

properties especially the hidrophobicity (contactangle) and the porosity of paper.

– MC coated samples show the best results in foldingendurance (double folds).

5. References1. S. E. Bruun: Starch, Papermaking Science and Technology,

Pigment Coating and Surface Sizing of Paper, Finish PaperEngineers Association and TAPPI, Helsinki, Finland, 2002, 11,241–229.

2. R. L. Feller, M. Wilt: Evaluation of Cellulose Ethers forConservation, The Getty Conservation Institute, 1990, 3, 3–19.

3. J. Vodopivec, M. Černič-Letnar: Applying synthetic polymers toconserve cultural property on paper, Restaurator, 1990, 11, 34–47.

4. M. Černič-Letnar, J. Vodopivec: Optimizing the LeafcastingTechnique, Restaurator, 2004, 25, 1–14.

Figure 5: The effect of starch and MC surface coatings onthe ISO opacity of the paper samples.


5. J. Vodopivec, S. Grkman, M. Černič-Letnar, M. Berovič: Effectof Starch coating during the leaf-casting technique, Proceedingsof the ICOM – CC Graphic documents meeting, Ljubljana,Slovenia, March 2004, 40–42.

6. ISO 536 – Paper and board – Determination of grammage.

7. ISO 534 – Paper and board – Determination of thickness andapparent bulk density or apparent sheet density.

8. ICP method – M/K-3D Formation Index (M/K Formation tester/floc analyzer).

9. ISO 1974 – Paper – Determination of tearing resistance.

10. ISO 2758 – Paper – Determination of bursting strength.

11. ISO 5626 – Paper – Determination of folding endurance.

12. TAPPI 451 – Flexural properties of paper (Clark stiffness).13. ISO 5627 – Paper and Board – Determination of smoothness

(Bekk method).14. ISO 5636-5 – Paper and board – Determination of air permeance

(medium range) – Part. 5: Gurley method.15. TAPPI 558 – Surface wettability of paper (angle of contact

method).16. ISO 2470 – Paper, board and pulps – measurement of diffuse

blue reflectance factor (ISO brightness).17. ISO 2471 – Paper and board – Determination of opacity (paper

backing) – diffuse reflectance method.18. ISO 9416 – Determination of light scattering and absorption

coefficients (using Kubelka-Munk theory).


EXPERIMENTAL RESULTS OF AGED TREATED PAPER WITH SOMECONSOLIDANTSAbdel-Salam M EL-Easely*1, Marion F. Mecklenburg2

1 South Valley University, Conservation Dept., Sohag, Egypt2 Smithsonian Institution, SCMRE, Suitland-MD, USA

* corresponding author:*[email protected]

1. IntroductionCellulose ethers polymers are typically used for,pharmaceuticals, foods, paints, paper sizing, printingsand textiles. They consist of a wide diversity ofpolymers ranging from organic-soluble thermoplasticproducts to water-soluble food additives. They are moreeconomical to produce than natural gums and starchesas a result their importance has increased recently.1

In paper conservation, cellulose ethers have been usedalone or combined with starch pastes for structuralrepair such as lining, hinging, and mending. Theirmoisture holding, surfactant and anti-redepositionproperties made them useful as poultices for removingstains, old adhesives and other accretions. Dilutesolutions of cellulose ethers polymers have been usedfor sizing or resizing paper and this has a directapplication on this research. Cellulose ethers have alsobeen used for consolidating flaking of friable paints onilluminated manuscripts and as a binder for cellulosepowder fills.2

2. Effects of environmental conditions on theweight gain of the cellulose ethers

In order to study the effects of relative humidity onweight change the experimented cellulose ethers wereexposed to 50% relative humidity and 21.3 °C. Thepurpose of this experiment is to study how muchmoisture is gained over time when exposed.

Exposed samples were weighed at time intervals untillittle or no measurable weight change is observed. Fig1. shows how these materials absorb moisture whenexposed to the air and gradually reach the equilibrium.Water-soluble ethers, e.g., Methocels and Klucels(Methyl Cellulose and Hydroxypropyl Cellulose),absorb more moisture than organic-soluble ethers suchas Ethocels. Non-water soluble ethers, ethocel-10 andEthocel-100, absorb nearly no moisture. Klucel-G andKlucel-M show an intermediate percentage of moistureabsorption when compared with either Methocels orEthocels.

3. Application of Methyl cellulose (Mothocel)

Cellulose ethers exhibited different degrees of thermalstability. In order to study the effect of heat,discoloration and weight loss changes were measuredas an evaluation of the stability of the ethers. Thepowder forms of the ethers, as received from thecompanies, were exposed to 90 °C in air-circulating dryoven. Samples received even heat exposure. Sampleswere weighed at time intervals to determine the weightloss versus time. Feller mentioned that the amount ofweight that polymers lose during heating usuallyindicates degradation and is a simple measure of long-term stability3 thermal aging was continued untildistinct color changes were observed. Table 1 lists theweight loss% of the tested ethers.

Table 1: Percent Weight Loss % of Heated Ethers at 90°Cversus time (hours).

Material 112 Hours 1080 Hours 1872 HoursMethocel-K100LV 1.97 2.67 5.98Methocel-A15LV 2.39 3.08 7.44Ethocel-10S 2.20 3.25 5.55Ethocel-100S 0.68 4.48 7.75Klucel-G 0.69 14.80 17.91Klucel-M 3.34 20.12 22.19Whatman Paper#1 2.98 4.79 9.22Total Absorption 0.68 1.86 2.6

In brief, Methocels show almost no color change andvery little weight loss when exposed to heating overquite a long time, certainly long enough to observedistinct color and weight changes for all of the testedmaterials. These results suggested that they are fairlystable materials.

Figure 1: Weight Change of Cellulose Derivatives versusTime. Conditioning at 50% Relative Humidity and 23.4° C.


3.1 Changes of mechanical properties duringthermal ageing

The experiment included three Methylcelluloses,Methocel-A4C, Methocel-A15LV and MethocelK100LV.As mentioned before, Methocels absorb about3% of its original weight of moisture when conditionedat 50% relative humidity and 23°C. Although thermalaging does not affect the color over more than 1872hours, aged Methocels powders desorbs about 6–7% ofthe original weight.

Stress-strain curves of the treated and aged samplesshow that as the aging time increased, both the strainand the stress to failure decreased as shown in Fig 2.

3.2 Light stability

Both treated and control samples were exposed to lightaging under intense Ultraviolet lamps at a distance ofabout 20 cm between the lamp and the samples. Theywere exposed for more than 12 weeks at which declinein strength properties were observed. Figure 4summarizes these results, in which stress and strain tofailure are plotted versus aging time in weeks of bothmaterials Methocel-A4C and Methocel-A15LV.Exposure to ultraviolet for 12 weeks reduced thestrength of all samples to approximately the samevalue.

4. Application of ethyl cellulose (Ethocels)


Figure 2: Breaking Stress (psi) versus Time Aging (Hours) at90 °C and 75.3 RH of Treated Whatman Paper#1 withCellulose Derivatives.

Aged treated samples with Methocel-A15LV exhibitedlittle color change when compared to other treatedsamples, Figure 3 includes the yellowness index YIE313 of the humid thermal aged treated and controlsamples. While treated samples with

Figure 4: UV – Light Aging Effects on the Breaking Strain(in./in.) of the Treated Whatman Paper#1.

Figure 3: Yellownes Index, ASTM-E313, of the Aging, at90°C and 75.3% RH, of the Treated Whatman Paper#1.

Methocel exhibited a little more color change thancontrol alone, as seen in Figure 3, they underwent acolor change that far less than treated samples witheither Kymene-557H or with gelatin.

Figure 5: Breaking Stress (psi) versus Aging Time (Hours) at90°C and 75.3% RH of Treated Whatman Paper#1 withCellulose Derivatives.

From Figure 5, it is obvious that although the aginghours increased up to 700 hours, the strain to failure ofthe aged treated samples decreased only from about0.025 to 0.015. This means that aging up to this numberof hours reduced only the extensibility of the treatedsamples but the ultimate resistance to stress values arenearly the same.

After 1670 aging hours, it seems that both, the paperand the consolidant, are no longer resistant to the aging


conditions. Stress-strain curves in Figure 5 show thathumid thermal aging stiffened the treated paper withthis material eventually reduced the strength of thesample aging while at the same time increased thestiffness only at 1000 hours of exposure.

Treated paper samples with Ethocel-10S suffered littlecolor change in comparison to Kymene-557H or evento Gelatin as seen in Figure 3 which plot the yellownessindex E313 of the humid thermal aging effects on thecolor change of the treated aged and control samples.Samples treated with Ethocels and exposed toultraviolet light exhibited no measurable color changeeven after 12 weeks of exposure. This suggested that inthese materials color stability is not good indication ofmechanical stability.

5. Application of gelatinAnimal glues and gelatin are binders and adhesiveswith broad applications in the paper manufacturingindustry. They are used in both surface sizing andcoatings of papers4. It is well known that gelatin is oneof major sizing materials in paper industry with itsadvantages and disadvantages.


strength, but also exhibited much more extensibilitywhen compared to the untreated (Control) samples.

3.2 Light stability

Ultraviolet light aging does not change the color of thetreated samples with gelatin at all up to 2060 hours, thenumbers of hours that decreased the strength propertiesto less than 50%, as shown in Figure 7.

Figure 6: Breaking Stress (psi) versus Time Aging (Hours) at90 °C and 75.3% RH of Treated Whatman Paper#1.

On the other hand, humid thermal aging causes moreserious color change to the gelatin-treated samples thanthe control.. The color change was the in the secondorder of all the experimented materials in this researchas seen in Figure 3.

In conclusion, although treated samples with gelatinexhibit the highest values of strength, comparing to allof the experimented materials within this research, theygradually suffered observable degrees of color changeas a result of humid thermal aging.

6. References1. Kirk Othmer, Encyclopaedia of Chemical Technology, 3rd

edition, John Wiley and Son, 1979, 143.2. Paper Conservation Catalogue, AIC Book and Paper Group-46,

1989, 21.3. R. L. Feller and M. Wilt. Evaluation of cellulose Ethers for

Conservation, Getty Conservation Institute, 1990, 63.4. TAPPI Monograph Series No. 36, Protein Binders in Paper and

Paperboard Coating, Appleton, Wisconsin 1975, 105.

Figure: 7 Effects UV-Light Exposure on the Stress-StrainCurves of Whatman Paper No#1 Treated with Treated withGelatin.

Figure 6 shows that gelatin treated samples, beforehumid thermal aging, acquired not only considerable


PRESELECTION OF HISTORICAL BOOKS IN THE PROCESS OFTHEIR STABILIZATIONM. Reháková*, K. Vizárová, D. Jančiová, M. Valovičová, Š. VargaSlovak University of Technology in Bratislava, Faculty of Chemical and Food Technology, Bratislava, Slovakia


1. IntroductionThe aim of this experimental study was to propose themethods of the qualitative classification of historicalbooks from 19th and 20th centuries from the point ofview of their next preservation. A special selection ofbook collection before the next deacidification,conservation and strengthening processes is notnecessary. The secondary effects and partial restrictionsare published only1-3. It would be appropriate to developa simple and fast realizable method for considering thebooks state. This method could also predict booksbehavior in the technological steps of preservation.

2. ExperimentalCollection of 100 books of 20th century, kindly providedfrom Slovak National Library in Martin, was studied.The following parameters were measured: squareweight, thick of paper, the content of paper pulp, pH ofcold extract, surface pH of paper, the degree of sizing,folding endurance, tensile strain by subsistent norms(ISO, STN)4-10 and lignin content by spectrophotometricmeasurements of absorption at 280 and 457 nm (M40with photometric ball, Carl Zeiss Jena), surface pH byindicator papers (Macherey-Nagel), performancestability from steel point. 15 measurements wereperformed (at 3 pages localized in different places ofbook block and at 5 different zones on one page) per onebook. The following mathematical methods were usedfor statistical evaluation: analysis of variance(ANOVA), point estimators of parameters in the modelof analysis of variance, nonparametric statistics – theKruskal Wallis test, multivariante analysis of variance(MANOVA), correlation, cluster analysis.

3. Results and discussion

3.1 Acidity of paper

The acidity of ligno-cellulose materials was determinedby 3 various methods of the pH value measuring. Thestatistically significant difference was achieved betweenthem, but their correlation coefficient was determinedas very high: 0.95–0.96. The dependence of pH valueon the age of books was determined and is showed inFig. 1. The following results were obtained by statisticevaluation: the position of the measured place on pageinfluences the pH value, the location of the page in thebook does not influence the pH value, the book ageinfluences the pH value. It was found out that the textpart was the most acidic area, internal edge near the

back of the book was the least acidic and the marginshad almost the same pH values.

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3.2 Mechanical properties and degree of sizing

Results of mechanical properties measurement – tensilestrength (tensile index Xt), folding endurance (numberof DF), break through endurance (puncture depth PD)always in the machine direction (MD) and crossdirection (CD) and their relations to the degree of sizinghave shown, that all of mechanical properties mutuallydisplayed statistically significant correlation, especiallyin case of MD with higher coefficient of correlation(0.45–0.75). That signifies that one of themeasurements (semi-destructive method in longitudinalline) is sufficed in practical monitoring. The degree ofsizing didn’t show correlation with other mechanicalproperties.We expected improvement of the mechanical propertieswith shorter age of books. The hypothesis confirmedwith the exception of some cases. The illustration ofmechanical properties monitoring is in Fig. 2.

3.3 Lignin

Dying experiment using fluorglucinol was used toestimate lignin content (%L) and compared with thespectral method (determination of remission at 280 –R280, and 457 nm – R457). The correlation of thesemethods was significant with correlation coefficient0.61 and dependence was following: %L = 26.52 – 1.14R280.

Figure 1: Average of pH of 20th century books sorted bytheir age. Standard deviation was ± 0.1 for cold extractionand surface pH method and ± 0.2 for pH indicator method.


4. Summary and conclusionThe others parameters showed neither statisticalsignificance nor correlation with mentioned properties.The classification of books based on aciditymeasurements (by indicator), mechanical propertiesmeasurements (by steel point) and lignin contentestimated (by spectrophotometry) enabled theircategorization into four groups (Fig. 3). Four kind ofnext book protection were proposed. There were 14%of books in a very bad state and hand intercession wasneeded, 31% should be treated by deacidification andstrengthening, 49% should be treated by deacidificationonly and just 6% of books were in good state and noprotection was needed. Monitoring of book state independence of date of their origin is showed in Table 1.

Table 1: Categorization of 20th century books into the classesA–D.

Years Number Number Number Numberof books of books of books of booksin class A in class B in class C in class D

1900–1919 4 9 7 01920–1939 6 9 5 01940–1959 1 5 13 11960–1979 3 5 12 01990–2000 0 3 12 5

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Figure 2: Average of fold endurance of 20th century bookssorted by their age.

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Figure 3: Classification of books required protection; A –intercession of restaurators, B – deacidification andstrengthening, C – deacidification only, D – withoutprotection.

5. References1. W. Wächter, Bucher erhalten, pflegen und restaurieren,

Hauswendel, Stuttgart 1997, ISBN 3-7762-0402-8, 203–241.2. W. Sobucki, B. Drewniewska-Idziak, Survey of the preservation

status of the 19th and 20th century collections at the Nationallibrary in Warsaw, Restaurator, 2003, 24, 189–201.

3. J. Havermans, P. Marres, P. Defize, The development of auniversal procedure for archive assessment, Restaurator, 1999,20, 48–55.

4. STN ISO 536 Paper and board. Determination of grammage.5. STN ISO 534 Paper and board. Determination of thickness.6. M. Souček, Zkoušení papíru, SNTL, Praha, 1977, 66.7. STN ISO 6588 Paper, board and pulps. Determination of pH

aqueous extract.8. STN 500374 Testing of pulp and paper. Surface pH

measurement of pulp and paper.9. STN ISO 1924-2 Paper and board. Determination of tensile

properties. Part 2: Constant rate of elongation method.10. STN ISO 5626 Paper. Determination of folding endurance.


DEACIDIFICATION OF AGED NEWSPRINTSMiriam Turanova, Bohuslava Havlinova, Michal Ceppan*Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava, Slovakia* corresponding author: [email protected]

The study was aimed to the influence of paperdeacidification on the stability of graphic informationof offset newsprints during the ageing. Wood-pulpnewsprint paper naturally aged for about 20 years (50 g/m2) and high quality filter paper Whatman (Cat. No.1001 917, 85 g/m2) as a reference were used. Samplesof papers were printed with coldset offset inksRollotemp produced by Michael Huber GmbH,München.

Nontreated papers and deacidified papers were tested.Samples of paper were deacidified by pouring into 2%solution of Methoxy Magnesium Methyl Carbonate inMethanol and drying on a free air. The standardtechniques of accelerated ageing – moist heat (80 °Cand 65% relative humidity6), UV-A radiation (radiationintensity 29 W/m2, illumination intensity 60 000 lux,average temperature of sample 31–36 °C, 11–17%relative humidity, distance of samples from the source19 cm), daylight (samples were exposed to the light ofstandard sunlight through window’s glass, radiationintensity 3–25 W/m2, illumination intensity 4770–39500 lux, average temperature of sample 23–27 °C,32–37% relative humidity) and office light (sampleswere exposed to the light of standard office illuminatingfluorescent tube, radiation intensity 0.0031 W/m2,illumination intensity 600 lux, average temperature ofsample 15–18 °C, 18–22% relative humidity, distanceof samples from the source 150 cm) – were applied inthe stability investigation of original and deacidifiedpapers.

Deacidification of nonprinted samples leads to theimprovement or does not significantly affect themechanical properties of Whatman paper afteraccelerated ageing. On the other side, thedeacidification in most cases leads to the downgrade ofthe mechanical properties of the newsprint paper afteraccelerated ageing, e.g. the folding endurance7 issignificantly lower for deacidified samples afteraccelerated ageing (Figure 1). This downgrade wasprobably caused by significant lowering of the pH ofthe newsprint samples containing lignin afterdeacidification1, 4 (pH of the cold extract of nontreatedsamples – 5.20; pH of the cold extract of the treatedsamples around 9.7). The values of pH of cold extractwere obtained according to the ref.5.

The brightness9 of samples of newsprint paper (originalas well as that after accelerated ageing) is significantlylower than the brightness of the corresponding samplesof Whatman paper (Figure 2). In most cases, thedeacidification treatment does not significantly affectthe brightness of the samples of Whatman paper and

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Figure 1: Folding endurance of samples of Whatman paperand newsprint paper (W – original Whatman paper; WN –deacidified Whatman paper; NP – original [20 years naturallyaged] newsprint paper; NPN – deacidified newsprint paper;Nonaged – samples without accelerated ageing; Daylight –960 hours of daylight ageing; Office light – 3000 hours ofageing in office conditions; UV light – 96 hours of ageingunder UV-A source, 29 W/m2; Moist heat – Standardaccelerated ageing, 80 °C, 65%).

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leads to the further lowering of the brightness of thesamples of the newsprint paper.

The optical properties of the samples of Whatman paperand newsprint paper printed by standard process inkscyan (C), magenta (M), yellow (Y) and black (K) were


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on the optical properties of the printed samples of theWhatman paper is various and depends on the particularink and type of accelerated ageing. The colordifferences ∆ECMC of samples printed by yellow ink areshown on Figure 3.

Comparing with nontreated samples, the deacidificationtreatment using 2% solution of Methoxy MagnesiumMethyl Carbonate in Methanol leads to the downgradeof mechanical properties and lowering of brightness ofthe newspaper samples subjected to several types ofaccelerated ageing, while optical properties of colorprints on the these samples were not changesignificantly.

References1. V. Bukovský: Yellowing of Newspaper after Deacidification with

Methyl Magnesium Carbonate, Restaurator, 1997, 18, 25–38.2. K. McLaren: The Colour Science of Dyes and Pigments, (2nd ed.),

Hilger, Bristol, 1986, 143.3. R. W. G. Hunt: Measuring Colour, (3rd ed.), Fountain Press,

Surrey , United Kingdom, 1998, 77.4. H. J Porck: Mass Deacidification, An Update of Possibilities and

Limitation, European Commission on Preservation and AccessAmsterdam, Commission on Preservation and AccessWashington, 1996.

5. ISO 6588 : 1981 – Paper, board and pulps. Determination of .pHof aqueous extracts.

6. ISO 5630-4:1986. Paper and board — Accelerated ageing – Part4: Dry heat treatment at 120 or 150 degrees.

7. ISO 5626 : 1993 – Paper – Determination of folding endurance.8. ISO 13655 1996 – Graphic Technology – Spectral measurement

and colorimetric computation for graphic arts images.9. ISO 2470 : 1999 – Paper, board and pulps – Measurement of

diffuse blue reflectance factor (ISO brightness).

Figure 3: Color differences of the samples of papers printedby yellow ink.

evaluated based on the optical density and colordifference (∆ECMC) (Colorimetric properties weremeasured according to the ref.8 – D65 standardillumination, 2° standard observer, 45/0 illumination/detection geometry; color differences ∆ECMC werecalculated according to the ref.2, 3).

It was found, that the yellow ink is the most labile withthe respect to the all types of accelerated ageing, whilethe black ink is generally the most stable one. In mostcases, the deacidification treatment does notsignificantly affect the optical properties of the printednewsprint papers, the observed changes are within theacceptable tolerance. The effect of the deacidification


CONDITION SURVEY ATLAS FOR PHOTOGRAPH COLLECTIONSIstván Kecskeméti*EVTEK Institute of Art and Design, Vantaa, Finland

* István Kecskeméti: [email protected]

1. IntroductionPhotograph collections have a dual value. Individualphotographs and negatives are historic and authenticobjects of their time. They represent the technology andprocessing of the past. Primarily the values inphotograph collections are considered to be informativevalues. Nevertheless, it is of importance to survey thecondition of the collection as the first step in collectionmanagement.1

Photograph collections in museums, libraries andarchives are usually very large containing severalthousands of objects or even more. Therefore thoroughindividual survey of objects is too time consuming.Methods for surveying large amounts of photographicobjects have been developed recently.1-4 No standard forsurveying of large collections has still yet been made.2

Statistic approach is often used in surveying largecollections of books and archival materials. 5 Randomsampling is not always a good option due to the veryspecific deterioration behaviour of photographmaterials. Several studies have presented the differentdeterioration phenomena characteristic for photographicmaterials.6-10 Many different deterioration factors arepresent, both internal (e.g. bad processing, acidhydrolysis of acetate film base) and external (e.g.climatic) factors. Due to the specific laminated structureand very sensitive image layer deterioration behavioursof photographic materials are specific.

2. MethodThis work has started with in 2002 and it has alreadybeen used by the conservation students of our Institutein condition surveying of different photographcollections. It has been also in use on the surveying ofUno Wegelius collection of 856 glass plate negatives.The method will also be adapted for book and archivalmaterials in the education of paper conservator studentsof our Institute. The surveying method consists ofcategorisation of damages types and damage amounts.An essential part of the surveying method is aCondition Survey Atlas for giving details of thecategories and an EXCEL form, where the results arepresented. This poster will concentrate to the conditionsurvey of silver gelatine glass plate negativecollections.

2.1. Categorisation of damage types

Damages of glass plate negatives are divided in 6groups according to the most usual damages. They are:

A – damages caused by biologic factorsB – emulsion damages, both caused by mechanical or

climatic reasonsC – silver mirroringD – yellowed or bleached silver imageE – dirt or other foreign material presentF – damages of the base material

2.2. Categorisation by amount of damage

It is common to use numbers from 0 to 3 to indicate theamount of damage.1-3

0 – no damage1 – slight damage, no need for conservation2 – moderate damage, need for conservation; should be

controlled3 – severe damage, need for acute conservation

2.3. Data of survey results

The survey data will consist of three different files. Theresults of the survey are written on Excel writing file.From writing file the results will be automaticallytransferred to the Survey Printing File. The programwill calculate the total amount of different damagetypes and also the total amount of damage severeness(table 1). From those results one can plan the active andpreventive conservation needs for future care. For onefile the information of 200 negatives can be written.The form was planned by István Kecskeméti andrealised by a student of paper conservation IlkkaHeikkinen in autumn 2002.

With this surveying method one can survey thecondition of 500–800 glass plate negatives per day,depending on how they are reached from their storageenvelopes.

Table 1: The results of different damages and the severity ofdamages.

1 2 3 Totally:A: biological 0 3 1 4B: emulsion 84 44 0 128C: silver mirror 126 39 14 179D: bleac/yell 14 3 0 17E: dirt 2 0 0 2F: base material 0 0 0 0Totally: 226 89 15

3. Condition Survey AtlasIn order to interpret the survey results by the same wayby different individuals an illustrated Condition Survey


Atlas was created. In this Atlas each damage categorywith letter and number are described. Severalphotographs belonging to most categories have beentaken to make the identification of damages moreprecise. During the planning of Atlas no sampling fromcollections was made; Uno Wegelius collection of 856glass plates was surveyd as a whole.

4. DiscussionThis Condition Survey Atlas is planned for surveyingthe condition of one specific photographic technique ata time. Most of the catalogued collections are organisedand stored by different techniques. The main purpose ofthe Atlas is to create a surveying system to get moreinformation of the deterioration of large collections.This will help to plan the needed conservationtreatments. This survey system can be adapted easily toother photographic techniques and also to book andarchival materials. It is possible to use this ConditionSurveying Atlas to survey whole collections or tochoose parts of larger collections by random sampling.

5. References1. J. S. Johnsen, Conservation Management and Archival Survival

of Photographic Collections, Acta Universitatis Gothoburgensis,Sweden, 1997.

2. Katja R. Glud and J. S. Johnsen, Survey of the still photographcollection at the Danish Film Institute, Works of art on paper,books, documents and photographs, 2002, AIC Baltimorecongress.

3. Anne Aune, Jesper Stub Johnsen, Fotokonserveringsprosjektet(The Photographic Conservation Project), En undersökelse avoppbevaringsforholdene og tilstanden i 14 norske fotosamlinger,1995–1996, Norsk Kulturråd.

4. D. G. Horvath, The Acetate Negative Survey, Final Report.University of Louisville, 1987 Louisville.

5. M. C. Drott, ‘Random sampling: a tool for library research’,College and Research Libraries, 1969, 30(2), 119–125.

6. Delamotte, “First report of the committee appointed to take intoconsideration the question of the fading of positive photographicpictures upon paper”, Photographic Journal, 1855, Vol. 2, No.36, pp. 251–252.

7. R.W. Henn and D. G. Wiest, ”Microscopic spots in processedmicrofilms: their nature and prevention,” Photographic Scienceand Engineering, 1963, vol 7, no 5, pp. 253–261.

8. P. Z. Adelstein, J. M. Reilly, D. W. Nishimura, and C. J.Erbland, “Stability of Cellulose Ester Base Photographic Film:Part I – Laboratory Testing Procedures”. Society of MotionPicture and Television Engineers Journal, 1992, Vol. 101, pp.336–346.

9. Henry Wilhelm, The Permanence and Care of ColorPhotographs: Traditional and Digital Color prints, ColorNegatives, Slides, and Motion Pictures. Preservation PublishingCompany, Iowa, 1993.

10. Giovanna Di Pietro, Silver mirroring on silver gelatine glassplate negatives, inaugural dissertation, 2002, Der UniversitätBasel.


VISCOSITY MEASUREMENTS. MARTIN EQUATION VERSUS MULTI-POINT METHODSJ. M. Łagan*

Jagiellonian University, Regional Laboratory for Phys-Chem. Analyses and Structural Research, Kraków, Poland* corresponding author: [email protected]

1. General considerationsChemists tend to regard viscosity as a specific propertyof fluids (both liquids and gases), but for a physicistviscosity is rather a coefficient used in the equations offlow.1,2 This physical point of view explains whyexperimental determination of viscosity of cellulosesolutions in organic solvents greatly depends on theapplied method (equation, type and geometry of theviscometer), and a necessity of standardization of thesemeasurements is obvious. At present, national standardsrequire that the intrinsic viscosity of cellulose [η] iscalculated according to one-point Martin equation fromdata obtained with a viscometer of strictly determinedgeometry.3,4 This method is fast and sufficiently reliablebut it is used only in paper industry and preservationscience. Generally, the intrinsic viscosity of polymersshould be determined by one of multi-point methodsbased directly on the following equation:5

(1)

where: [η] – intrinsic viscosity of polymer, η0 –viscosity of solvent, η – viscosity of solution, c –concentration of solution, D – shear velocity.

Polymer handbooks give a general dependence ofviscosity of a polymer solution on its concentration6:

(2)

From this equation the most commonly known multi-point equations can be derived – those of Huggins7,Kraemer8, and Schulz and Blaschke9. Practicalapplication of these equations needs much tediouslaboratory work and usage of series of viscometers ofvarying geometry in order to be in accordance with therequirement of shear velocity approaching zero.

2. One-point Martin methodIn 1951 Martin10 suggested the use of a much simplerone-point method, but no information about the originof his equation was given in the paper. An attempt ofreconstruction of the probable path of mathematicalconsiderations, used in order to arrive at the finalequation, will be presented below.

This seems to be very simple. When higher-order termsin equation (2) are neglected, one obtains the wellknown Huggins equation

(3)

After applying logarithmic transformation to thisequation one arrives at its other form

(4)

and taking into account the approximation:

ln(1 + x) ≅ x (5)

the final result is obtained:

. (6)

This is the logarithmic version of the Martin equation.

But there is a trap hidden in these calculations. Onemust remember that some numerical errors aregenerated through approximate formulae. For example,this specific approximation in eq. (5) generates a 10%relative error when –0.2 < x < +0.2. Let’s have a closerlook at the consequences. Both standard3 and thesecond Martin publication11 require fulfillment of theinequality 2.5 < [η]c < 3.5. If we take into account onlysmaller of these limits and the value of Martin constant(K ≡ k1) equal to 0.3, it is easy to observe that theobtained value of the expression K[η]c = 0.75 is muchhigher than the allowed value of x in the approximation(5). Therefore the generated numerical error greatlyexceeds 10%. The conclusion seems to be obvious:though derived from the same basic equation (2), fromwhich various multi-point equations are stemming,Martin equation cannot be treated as a basis for multi-point viscosity measurements.

Nevertheless, the Martin one-point method givesreproducible results when used in the case of cellulosesolved in cupriethylenediamine. Therefore equation (6)must be regarded as an empirical equation of limitedapplicability. However, its unquestionable simplicityand strictly determined geometry of viscometer, as well

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as strictly defined experimental conditions, make thismethod a perfect tool for rapid determination ofintrinsic viscosity of cellulose3,4.

3. ExperimentsBeing fully aware that the Martin equation cannot beused for multi-point viscosity determination, wenevertheless tried to compare it with two other multi-point equations – that of Huggins, see eq. (3) andKraemer:

(7)

which can be also derived from equation (2) byapplying the approximate formula (5). Themeasurements have been done on samples of two modelpapers P1 and P2 (described in publication12). Thepreliminary results, presented in Table 1, were bothinteresting and unexpected.

Table 1: Intrinsic viscosity of cellulose calculated by variousequations. For multi-point methods correlation coefficientsare given.

Type of paper P1 P2Huggins equation 233 ± 25 644 ± 12

r = 0.9976 r = 0.9931Kraemer equation 354 ± 44 626 ± 5

r = 0.7169 r = 0.9953Martin equation (multi-point) 331 ± 40 655 ± 13

r = 0.9725 r = 0.9868Standard Martin equation 618 599

It seems that mutual accordance of the obtained valuesof intrinsic velocity depends on the type of paper being

studied. For paper P1 the results obtained by multi-point equations are much lower than the valuecalculated according to the standard3. This is not thecase with paper P2, where, unexpectedly, all appliedformulae lead to very similar values. This phenomenonundoubtedly deserves further studies – possibly notonly on cellulose solutions in cupriethylenediamine, butalso for other polymers.

4. References1. R. B. Bird, W. E. Stewart, E. N. Lightfoot, Transport

Phenomena. J. Wiley & Sons, New York–London, 1960,Chapters 1–2.

2. C. O. Bennett, J. E. Myers, Part 1: Fluid Dynamics, in:Momentum, Heat, and Mass Transfer. McGraw-Hill, New York,1962.

3. Scandinavian Pulp, Paper and Board Testing Commitee,Viscosity in cupri-ethylenediamine solution, Standard SCAN–CM 15: 88.

4. Polska Norma PN-92 / P-50101/01, Celuloza w rozcieńczonychroztworach. Oznaczanie lepkości granicznej. Część 1: Metodaoznaczania w roztworze etylenodwuaminomiedziowym (CED).

5. E. Gruber, R. Gruber, Viskosimetrische Bestimmung desPolymerrisationsgrades von Cellulose, Papier, 1981, 35, 133.

6. M. Stickler, N. Sütterlin, Concentration Dependence of theViscosity of Dilute Polymer Solutions: Huggins and Schulz-Blaschke Coefficients, in: Polymer Handbook, 3rd ed. J.Brandrup, E. H. Immergut (Eds.), New York, John Wiley &Sons, 1989.

7. M. L. Huggins, J. Am. Chem. Soc., 1942, 64, 2716.

8. E. O. Kraemer, Ind. Eng. Chem., 1938, 30, 1200.

9. G. V. Schulz, F. Blaschke, J. Prakt. Chem., 1941, 158, 130;ibid., 1941, 159, 146.

10. A. F. Martin, Toward a Referee Viscosity Method for Cellulose,TAPPI, 1951, 34, 363.

11. F. H. Wetzel, J. H. Elliot, A. F. Martin: Variable ShearViscometers for Cellulose Intrinsic Viscosity Determination,TAPPI, 1953, 36, 564–571.

12. J. B. G. A. Havermans, Restaurator, 1995, 16, 209–233.

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EXPERIMENTAL VERIFICATION OF ZOU, UESAKA AND GURNAGULFORMALISM, BASED ON KINETIC DATA OBTAINED FOR VARIOUSKINDS OF PAPERA. Barański*1,2, J.M. Łagan2, T. Łojewski1, T. Sawoszczuk1

1 Jagiellonian University, Department of Chemistry, Kraków, Poland2 Jagiellonian University, Regional Laboratory for Phys-Chem. Analyses and Structural Research, Kraków, Poland


1. IntroductionApplication of Arrhenius equation in predicting paperand pulp permanence, where a multiple-reaction systemwith different activation energies should be taken intoaccount, has been seriously questioned by manyauthors. However, Zou and co-workers1 achieved abetter understanding of the apparent activation energyeven in the case of multiple parallel reactions, andjustified the extrapolation based on Arrhenius plot.Their approach was a very promising one, but,unfortunately, this publication was not widelyrecognized among the researchers working in the fieldsof papermaking and preservation science. Strongexperimental evidence of validity or falsity of thisapproach is still lacking.

The equation used in paper1 is based on a well knownand widely used Ekenstam equation2 and has thefollowing form:

95% of cellulose from coniferous trees and 0.45% ofash) at temperature 90 °C and at various relativehumidities (from 10 to 75%)4. Samples of paper P1have been obtained from TNO, Delft.5 It should bestressed here that two different reams of P1 paper,differing slightly in the original value of polymerizationdegree, have been obtained from this source.

Another set of well documented kinetic data can betaken from the report of Kaminska, Bégin et al.6. Theauthors used in their experiments two other kinds ofpaper – BNSWK softwood ISR paper #1 (BleachedNorthern Softwood Kraft fibre, rosin sized) and SW-BCTMP softwood ISR paper #3 (BleachedChemiThermoMechanical Pulp fibre, unsized). Thetemperature range used by Kaminska and Bégin was65–90 °C, and the relative humidity range was 65–72%.

For comparison, one of the kinetic runs obtained byZou, Uesaka and Gurnagul has been chosen in order tocheck applicability of the same equation parameters(averaged over temperatures and humidities) to a singlecurve. The samples used in the experiments of Zouwere those of softwood bisulfite pulp (BBSP)originating from various Canadian paper mills andformed into standard handsheets (60 g/m2).

3. Results and DiscussionThe most important data concerning the kinetic resultsare presented in Table 1. Typical curves have beenshown in Fig. 1.

The reader should be aware that the residual standarddeviation (RSTD) values given in Table 1, thoughobtained as a result of linear regression analysis, havebeen recalculated so as to show differences betweenexperimental data and theoretical curves in the naturalsystem of coordinates: DP versus time.

The worst results of fitting the discussed model to theexperimental data have been obtained for Kaminskaand Bégin paper SW-BCTMP. The remaining resultswere quite promising. Most of the investigated kineticcurves were quite satisfactorily predicted by the model,though in almost all cases the experimental points weresituated below the calculated curve, this meaning thatreal degradation rate was somewhat higher than thecalculated one. Experimental degradation progressingfaster than that predicted by the discussed model couldbe explained by the fact that the model assumes a

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where

Aa = Aa0 + Aa2[H2O] + Aa5[H+][H2O].

Symbol [H2O] denotes the moisture content in paper.As the concentration of hydrogen ions in paper cannotbe measured, the value of [H+] was recalculated fromthe experimentally determined pH value of paper. Theparameters Aa0 , Aa2 , and Aa5 , as well as the activationenergy Ea, should be empirically determined for theinvestigated kind of paper. However, they are notindependent, and if one wants to use the equation for adifferent kind of paper, it is necessary to find thesuitable values simultaneously. One can try, however,to find at least an approximate prediction of theinvestigated paper ageing behaviour using the originalset of values published in the second part of the citedpublication3. This is exactly what we did. We tried touse the parameters of Zou and co-workers equation tothe papers differing from the material used in theoriginal experiments described in the literature.1,3

2. Types of papers usedWe decided to check the applicability of Zou, Uesakaand Gurnagul formalism, taking our kinetic dataobtained for the model P1 paper (containing more than


constant concentration of hydrogen ions during thedegradation process, whereas our own experimentalresults7 clearly show that pH is lowered during theartificial ageing tests, thus resulting in the accelerationof acid hydrolysis process.

4. ConclusionThe results presented here, though not conclusiveenough, speak strongly in favor of Zou, Uesaka andGurnagul formalism. It seems possible to apply thevalues of parameters experimentally obtained by these

Table 1: Selected experimental details of kinetic results obtained for various kinds of paper. The Kraków data have beenobtained for P1 paper originating from different paper reams.

Source of Zou Kaminska, Kaminska, Kraków Krakówdata et al. Bégin Bégin

[1] [6] [6] [4] [4]Paper type BBSP BNSWK SW-BCTMP P1 P1Temperature range 90 °C 65–90 °C 65–90 °C 90 °C 90 °CRH range 75% 65–72 65–72 10–45 23–75DP0 value 1369 2475 1858 921 997Number of kinetic curves 1 4 4 2 2Mean value of Residual Standard Deviation (RSTD) in DP units 72 122 188 69 35

Figure 1: Kinetic curves calculated according to Zou, Uesakaand Gurnagul model (lines), as fitted to the experimental data(points) obtained in various laboratories at temperature 90 °Cand relative humidity close to 75%.

authors for the rough estimation of kinetic behaviour ofpapers originating from different sources. Of course,better results will be, most probably, obtained if a set ofequation parameters is experimentally determined forthe specific kind of paper being investigated. Anotherimprovement in the original model could be achievedby taking into account variation of the hydrogen ionconcentration in the course of accelerated ageing tests.

5. References1. X. Zou, T. Uesaka, N. Gurnagul, Prediction of paper

permanence by accelerated aging. I. Kinetic analysis of the agingprocess, Cellulose, 1996, 3, 243–267.

2. A. Ekenstam, Über das Verhalten der Cellulose in Mineralsäure-Lösungen, II Mitteil: Kinetisches Studium des Abbaus derCellulose in Säure-Lösungen, Ber., 1936, Band I, Abt. B, 551.

3. X. Zou, T. Uesaka, N. Gurnagul, Prediction of paperpermanence by accelerated aging. II. Comparison of thepredictions with natural aging results, Cellulose, 1996, 3, 269–279.

4. A. Barański, D. Dutka, R. Dziembaj, A. Konieczna-Molenda, J.M. Łagan, Effect of Relative Humidity on the Degradation Rateof Cellulose. Methodology Studies, Restaurator, 2004, 25, 68–74.

5. J. B. G. A. Havermans, Restaurator, 1995, 16, 209–233.

6. E. Kaminska, P. Bégin, D. Grattan, D. Woods, A. Bullow, ASTM/ISR Research Program on the Effects of Ageing on Printing andWriting Papers: Accelerated Ageing Test Method Development,Report of Canadian Conservation Institute CCI No. 70664,November 2001.

7. A. Barański, R. Dziembaj, A. Konieczna-Molenda, J.M. Łagan,S. Walas; On the applicability of Arrhenius equation toaccelerated ageing tests. The case of alum-impregnatedcellulose; Polish Journal of Chemical Technology, 2004, 6, 1–8.


DEGRADATION OF PAPER AS STUDIED BY FIBER LENGTHMEASUREMENTS AFTER HYDRODYNAMICAL TREATMENTT. Sawoszczuk1, P. Wandelt*2, A. Barański*1,3, J. M. Łagan3, T. Łojewski1, K. Perlińska-Sipa2

1 Jagiellonian University, Department of Chemistry, Kraków, Poland2 Technical University of Łódź, Łódź, Poland3 Jagiellonian University, Regional Laboratory for Phys-Chem. Analyses and Structural Research, Kraków, Poland

* corresponding authors: [email protected]@p.lodz.pl

1. IntroductionComprehensive characterization of deteriorating papersis a prerequisite of selecting the best methods for theirpreservation. In this context, it is important to learnhow macromolecular changes influence mechanicalproperties of paper.

Properties of cellulose chains determine the propertiesof cellulose fibers. A decrease in the degree of poly-merization of cellulose lowers mechanical resistance offibers, thus making them susceptible to shortening dueto mechanical treatment. Consequently, mechanicalproperties of paper are also changed. A scheme of thiscause-and-effect chain of the degradation process canbe drawn:

2.2 Equipment

Morphological properties of fibers were determinedwith a MorFi LB-01 fiber analyzer, produced byTechpap, France. The analysis is done on a fibernetwork, so that the measurement occurs in the naturalunrestrained environment of fibers. This approachallows for a reliable statistical measurement of thou-sands of fibers at high speed and accurate determinationof important characteristics of their shape.

2.3 Defibration procedure

The samples of degraded paper had to be defiberedprior to a measurement in a simple domestic blenderused as a disintegrator. Direct action of the blenderknives, as well as the action of water whirl produced by

the rotation of knives, were thedefibering agents. In order to minimizethe destructive action of knives, thedefibering process (of total duration timeequal to 3 minutes) was done in cycles:blender switched on for 5 seconds, then

blender switched off for 10 seconds.

2.4 Fiber length measurements

The length of fibers was measured automatically in theMorFi apparatus by a computer analysis of images ofthe suspension flowing through a flat cell observed by adigital CCD video-camera. The analysis of morpho-logical properties of fibers performed by MorFi LB-01provided arithmetical average length of fibers (thevalue most sensitive to the effect of shortening ofdegraded fibers during their mechanical treatment),expressed by the equation

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Studies on the dependences DP = DP(t) andMP = MP(DP) exist in the literature, but description ofa possible relation between fiber length and DP is hardto be found. Characterization of paper degradationthrough the studies of fiber length has several practicaladvantages:

a) a small amount of paper is necessary for themeasurement (0.1 g sample, about 14 cm2, wouldsuffice);

b) paper samples covered with print, as well as thosecontaining lignin, can be studied;

c) the measurements are fast.

2. Experimental

2.1 Samples

The experiments were carried out on a sample of modelpaper P1 (containing more than 95% of cellulose andobtained from TNO, Delft1), previously subjected toaccelerated aging2. Some samples had beenimpregnated with aluminum sulphate prior toaccelerated aging3 in order to achieve an effect ofdegradation more advanced than that obtained for thenon-impregnated samples after the same degradationperiod.

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where zi is the number of fibers in a given class oflength, and li is the mean length of fibers in the givenclass. Additionally, a determination of the degree ofcellulose polymerization (DP), for all samples tested byMorFi LB-01, has been done viscometrically, inaccordance with the SCAN-CM 15:88 standard.

2.5 SEM measurements

Another method of defibering of samples consisted in agentle shaking of paper sample in a small bottle partly


filled with water. After defibration, suspensionscomposed of separate fibres were obtained. From thesesuspensions small handsheets (1 cm2 in diameter) weremade. The length of fibres could be measured from thephotographs of handsheets, made by Scanning ElectronMicroscope.

3. Results and Discussion

regarded as negligible). This decrease is due to thepresence of sensitive places in the structure of degradedfibers. These places are distinguished by a very weakmechanical strength. It can be postulated that for DPvalues below 450 the number of weak points in fibers isso great that even a delicate mechanical treatment canbreak off the fibers.

When a dependence of average length of fibers on thepolymerization degree of cellulose is drawn for allsamples impregnated with aluminum (Figure 3), anexistence of a logarithmic relation can be supposed.Such a hypothesis has been forwarded by Akcetin andVerschraege4. However, more experimental data in theregion of lower DP values are necessary in order toobtain a more unequivocal confirmation of thissupposition.

A comparison has been made between the values offiber length obtained from SEM photographs and thosemeasured with MorFi LB-01. Both values were of thesame order of magnitude. The differences fall withinthe interval of (+10 ÷ –33)% of the value obtained fromMorFi LB-01. If the action of knives was a criticalsource of shortening of fibers, then the values of fiberlength obtained from the analyzer would besignificantly lower.

Figure 1: Changes of arithmetical average length of fibers(FL) and the polymerization degree of cellulose (DP) forpaper sample S31 (90 °C, RH = 100%, 0.8‰ of Al) as afunction of time.

The dependence of both measured quantities – degreeof cellulose polymerization (DP) and average fibrelength (FL) – on time has been shown in Figure 1. Bothcurves are similar and running approximately inparallel, thus confirming existence of correlationbetween polymerization degree and fiber length.

However, this correlation was established only forpaper samples containing cellulose with polymerizationdegree below 450, as illustrated by Figure 2.

Figure 2: Dependence of arithmetical average length offibers (FL) on the polymerization degree of cellulose (DP)for paper samples S31 (90°C, RH = 100%, 0.8‰ of Al) andS14 (90°C, RH = 100%, 0.0‰ of Al). Degradation times areindicated in the drawing.

It has to be stressed that a decrease in the arithmeticalaverage length of fibers is an effect of weak mechanicaltreatment of sample, being the result of water whirlonly (results of action of the blender knives was

4. ConclusionsDetermination of properties of cellulose fibers can beuseful in paper degradation studies. However, essentialdecrease in arithmetical average length of fibers,correlated linearly with the decrease in cellulose DPvalues was observed only for paper samples aged for along time, or under conditions increasing the rate ofhydrolysis of cellulose chains. It is proposed thatmeasurements of arithmetical average length ofcellulose fibers can be used as an indicator of papercondition in books and printings, because for this kindof measurement only a small piece of paper is needed –as compared with other methods used in conservationpractice.

Figure 3: Dependence of arithmetical average length offibers (FL) on the polymerization degree of cellulose (DP)for all paper samples impregnated with aluminum.


5. References1. J. B. G. A. Havermans, Restaurator, 1995, 16, 209–233.2. A. Barański, R. Dziembaj, A. Konieczna, A. Kowalski, J. M.

Łagan, L. M. Proniewicz: Methodology of kinetic investigation ofcellulose degradation. Chemical Technology Between Centuries,Permanent Committee of Chemical Technology Congresses,Gliwice, Poland, 2000, 441–450.

3. A. Barański, R. Dziembaj, A. Konieczna-Molenda, J. M. Łagan,S. Walas, On the applicability of Arrhenius equation toaccelerated ageing tests. The case of alum-impregnatedcellulose, Polish Journal of Chemical Technology 2004, 6, 1–8.

4. D. Akcetin, L. Verschraege, Relation between the degree ofpolymerization, the fiber strength, and the breaking elongation,Textilis 1974, 10, 16.


CONTROL OF AQUEOUS PAPER TREATMENTS WITH IONCHROMATOGRAPHYUlla Knuutinen*, Istvan Kecskemeti, Ilkka Heikkilä and Tuomo RaappanaEVTEK Institute of Art and Design, Vantaa, Finland


1. IntroductionThere are several aqueous conservation treatments forpaper materials in use: cleaning/washing with water,deacidification/ neutralisation treatments and aqueousmethods for the stabilisation of iron gall ink containingpaper. The effectiveness of these processes has beenstudied mainly by analysing changes in paperproperties.1-4 With few exceptions, the only commontreatment control was provided by determination ofpH.5

The purpose of this study was to test the usability of IC(ion chromatography) for the control of washing ofpaper materials, for the monitoring of deacidificationwith calcium hydroxide and sodium phosphate, as wellas in studies of phytate treatments.

Sampling for the IC analyses can be performed non-destructively, by taking samples directly from treatmentsolutions, or destructively, by making extracts of thetreated papers. This paper presents some preliminaryresults of IC analyses of washing and conservationtreatment solutions. More results will be publishedlater.

2. Experimental

2.1 Ion chromatography

IC is a liquid-chromatographic technique in which theprinciple of separation involves ion-exchange. It is usedfor qualitative and quantitative analyses of ioniccomponents in complex matrices. The separationproceeds between the stationary phase with functionalgroups, and the mobile phase, which moves through thecolumn. The ionic components of a sample areseparated on the basis of their different affinities for thestationary phase. Factors that control the separationinclude column type (length, resin type, particle size),eluent, its concentration and flow rate. Detection limits(depending on the detector) under normal operationconditions are in sub-ppm to ppm range.6,7

The Metrohm 761 compact high-performance ionchromatography system, was used with Dialysis (754IC) unit to analyse both anionic and cationic samples.As a pre-treatment, the dialysis unit separated highmolecular (colloidal) substances from the injectedsolutions.

For anionic analyses Metrosep A Supp 5-100(6.1006.510) Column, size 4.0 × 100 mm and particlesize 5.0 µm was used with 3.2 mmol/L Na2CO3/1.0

mmol/L NaOH eluent with suppression. The separatingphase of the column consisted of polyvinyl alcoholcoated with quaternary ammonium groups. Theseparated ions were detected using a conductivitydetector. Conditions for anionic analyses were:Injection volume 20.0 µL, flow rate 0.70 m L/min,temperature 20.0 oC and pressure 13.2 MPa. Theanionic analyses were calibrated to detect and quantifysulphate, phosphate, chloride and fluoride anions.

For the cationic analyses the Metrosep C 2-250(6.1010.230) cation column, size 4.0 × 250 mm andparticle size 7.0 µm was used with 4.0 mmol/L tartaricacid and 1.0 mmol/L dipicolinic acid eluent. Conditionsfor cationic analyses were: injection volume 20.0 µL,flow rate 1.2 m L/min, temperature 20.0 oC andpressure 13.2 MPa. The cationic analyses werecalibrated to detect and quantify sodium, ammonium,potassium, calcium and magnesium cations.

2.2 Samples

Rag paper, sample A (cotton linters, 1840’s) and lignincontaining mechanical pulp, sample B (newspaper,1920’s) were used. 2 × 1.5 g of each was washedseparately in purified (Millipore, ElixTM) water (500mL) in a beaker for 15 min and the washing (20 oC)solutions were analyzed with IC after dialyses.

Two batches of 0.27 mmol/L calcium phytate solutions(solution I and solution II) 2 L each, were madeaccording to Neevel’s recipe from p.a grade phytic acid,calcium carbonate in purified water and pH of solutionswas adjusted to pH 5.6 (WTW pH Meter 330) withammonium hydroxide.8

3. Results and DiscussionThe IC chromatograms (Figure 1) show three identifiedwater-soluble anionic substances, which were washedout from paper samples. IC analyses offer directinformation on the amount of water-soluble sulphates,which are washed out during the aqueous process.

More sulphates washed out from old rag paper, sampleA (2.7 mg/L) than from newspaper, sample B (1.4 mg/L).The SD (standard deviation) value for sulphatecation analyses is ±0.3 mg/L. Purified water itselfcontained sulphate only in trace amount. Of course, ICanalyses cannot reveal the origin of sulphate and it isobvious that internal and external sources of sulphatescan be different in different papers.9


Table 1 gives the results of IC analyses on contents ofcertain ions in calcium phytate solutions. IC analysesshow that different concentrations of soluble calcium,ammonium and phosphate ions were performed in twodifferent batches (solution I and II) of identically madecalcium phytate solutions. Treatment solutions for irongall ink stabilisation are made from phytic acid,calcium carbonate and ammoniac. They are mixtures ofcalcium-, and ammonium phytate containing bothsoluble and insoluble complexes and ions. In theformation of calcium-phytate complexes other cations(in this case ammonium ions), if present in the samesolution, can intervene by forming both solid andsoluble species.10 It is evident, that pH measurementcombined with the solubility information of calciumphytate solution, is not a sufficient control for this kindof complex aqueous mixtures.11

The IC offers a possibility to analyse both solublecations and anions from these treatment solutions andalso provides an opportunity for studying changes inion composition during aqueous stabilisationtreatments.

Table 1: Ion contents of calcium phytate solutions I and II.Error is given as standard deviation.

Calcium phytate [PO43-] [Ca2+] [NH4

+]solution (mg/L) (mg/L) (mg/L)I 470 ± 8 92 ± 4 13 ± 1II 323 ± 8 117 ± 4 16 ± 1

In paper conservation, aqueous deacidificationprocesses are very often performed with saturatedsolutions of calcium hydroxide, which turn to calciumcarbonate or with calcium carbonate, which is almostinsoluble in water. Clear solutions over precipitates areused for the deacidification without knowledge of exactconcentrations of soluble calcium cations or other ions,which form the basis of the chemical conservationtreatment.12,13 In the deacidification/ neutralisationreaction cations (Ca2+, Mg2+) are important, becausethey take part in salt formation. They will be alsoadsorbed on paper and give alkaline reserve.Concentrations of cations in neutralising solutions andloss of cations from solution during sorption, as well as

possible washing out of cations and/or anions, can bestudied by the IC.

Adsorption of ions/salts can be monitored also frompaper extracts after treatment processes by destructiveIC analyses.

There are, anyhow, some limitations for IC analyses:use of chemicals of a high degree of purity (p.a.), whilefor preparation of solutions and eluents water of highpurity is needed.

4. SummaryThe preliminary results show that IC is a very usefultool for the study and control of aqueous treatments ofpaper. With this method one can follow the removal ofsulphates and other ions from paper into water used forwashing. Also the changes in ion concentrations (iontake up and wash out) in treatment solutions, used forstabilisation and neutralisation, can be examined.

With IC (either anionic or cationic), can achieved lowdetection limits and low sample consumption: typicalsample volume is 20 µl (even smaller samples arepossible). Repeatability, resolution, as well as linearityof calibration are unique for each cation and anion. Themethod was statistically evaluated.14 There are alsomany chromatographic parameters: dead volume,retention times, net retention times, standard deviationof peaks of individual components, selectivity (theseparation efficiency of chromatographic system),which need to be controlled before using IC routinely.Anyhow, even routine analyses must be made under thecontrol of a chemist.

5. References1. A. Moropoulou, S. Zervos, The Immediate Impact of Aqueous

Treatments on the Strength of Paper, Restaurator, 2003, 24,160–177.

2. V. Daniels, J. Kosek, Studies on the Washing of Paper,Restaurator, 2004, 25, 81–93.

3. F. Sundholm, M. Tahvanainen, Paper conservation UsingAqueous Solutions of Calcium Hydroxide/Methyl Cellulose. 2.The influence of accelerated ageing temperature on properties oftreated paper, Restaurator, 2003, 24, 178–188.

4. J. Kolar, M. Strlic, Evaluating the Effects of treatments on IronGall Ink Corroded Documents, A new analytical methodology,Restaurator, 2004, 25, 94–103.

5. H. Bansa, Aqueous Deacidification – with calcium or withMagnesium, Restaurator, 1998, 19, 1–40.

6. J. P. Sibilia, Ed., Materials Characterization and ChemicalAnalysis, Separation Techniques Ion Chromatography, Secondedition, 1996, VCH Publishers, Inc, 101–106.

7. A. Braithwaite, F. J. Smith, Chromatographic Methods, Highperformance liquid chromatography, Ion exchangechromatography, Fifth edition 1996, Blackie Academic &Professional, 332–338.

8. J. G. Neevel, (Im)possibilities of the phytate treatment..The irongall ink meeting, Newcastle 4th–5th Septemper, Postprints,University of Northumbria, Newcastle upon Tyne, 125–134.

9. J. L. Pedersoli Jr., Evaluation of efficiency of calcium hydroxideand of methyl ethers of cellulose. Department of PolymerChemistry of Helsinki University, MsC degree thesis 1994, 12–18.

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Figure 1: Determination of fluoride, chloride and sulphate inwashing solution of rag paper, sample A.


10. F. Crea, P. Crea, A. De Robertis and S. Sammartano, Speciationof Phytate Ion in Aqueous Solution. Characterisation of Ca-phytate Sparingly Soluble Spaces, Chemical Speciation andBioavailability, 2004, 16 (1/2), 53–59.

11. R. Jackman, C. A. Black, Solubility of Iron,Aluminium, Calciumand Magnesium Inositol Phosphates at Different pH Values,Soil. Sci., 1951, 7, 179–186.

12. B. Reissland, Ink Corrosion Aqueous and Non-AqueousTreatment of Paper Objects – State of the Art, Restaurator,1999, 20, 167–180.

13. J. Kolar, G. Novak, Effect of Various Deacidification Solutionson the Stability of Cellulose Pulp, Restaurator, 1996, 17, 25–31.

14. K. Huuhilo, Ion Chromatography and Dialysis in AnalysingWaste Water, 2003, EVTEK Institute of Technology, Vantaa,unpublished report.


THE CONSERVATION AND RESTORATION OF THE MANUSCRIPTS“LA BASTILLE”V. Belon*1, V. Godeaux1, T. P. Nguyen2

1 Bibliothèque nationale de France, Restoration workshop, Centre Technique “CTBnF”, Bussy Saint Georges, France2 Bibliothèque nationale de France, Laboratoire, France.

* Corresponding author: [email protected]

1. IntroductionWorkshops always have to deal with the treatment of alarge number of manuscripts containing iron gall ink.The CTBnF has tried to find a way to treat this kind ofdocument without damaging the ink. The use of waterto clean or leaftcast the paper is sometimes necessary,and we have tried to study its effect on the ink, parti-cularly on the iron ions.

2. History of the manuscriptsThe Bastille archives date from 1660 to 1786, andconcern prisoners and jail administration. They werestolen and scattered on the 14th of July during theFrench Revolution1. Now conserved at the “Biblio-thèque de l’Arsenal”, this enormous collection (about20 000 documents), preserves some evidence of its ownhistory as it is in poor condition and difficult to read byresearchers.

3. Condition of documentsThe documents are in various states of degradation butmost of them are folded, incomplete, full of dust andmud, and sometimes have been attacked by mould orbacteria.

of iron gall ink force us to make a choice betweendifferent treatments. The use of water (immersion) issometimes the only viable alternative if one wishes towash, flatten and leaftcast the documents to renderthem legible and preserve them.

Figure 1: Document 10217 A-2-37 before treatment.

Most of the inks on the treated documents are in goodor mediocre condition (Figure 2), and they are notsensitive to water. Unfortunately others are in poorcondition (Figure 3), particularly when they havesuffered from a water damage.

4. Conservation and RestorationEven though some of the documents are in goodcondition, the sheer quantity of them and the presence

Figure 2: Iron gall ink in mediocre condition.

Figure 3: Iron gall ink on a water-damaged document in poorcondition.

Figure 4: Document 10217 A-2-37 after leaftcasting.

Figure 5: Leaftcasting of a document damaged by iron gallink.


Leafcasting has many advantages, for example, it putsno stress on the borders because the technique uses noadhesives but recreates fiber bonds and it is a good wayto strengthen paper degraded by microorganisms. It is arapid treatment that preserves every piece of thedocument. Compared to lining, there is nothingattached to the whole surface of the document. Thistechnique boasts excellent legibility and reversibility.

5. Long term control of the inkThe use of water evokes up some questions: is thistreatment appropriate for this kind of ink despite thefact that it is in good condition and this is not ableeding ink? According to B.Reissland2, an aqueoustreatment may have side effects: it can activate an acidhydrolysis, or it can make iron ions move on the papersurface or it can discolour the ink. It is also establishedthat iron ions are harmful to paper as they catalyse theoxidation3. In order to control the effects of watertreatments on the iron ions we have used “the indicatorpapers for iron ions” developed by the NetherlandsInstitute for Cultural Heritage4.

5.1 Bathophenantroline spot tests

Firstly, test papers containing the indicator bath-ophenanthroline are prepared. The principle is thatwater-soluble iron salts migrate into a dampenedindicator strip that is brought in contact with the surfaceof the document. The bathophenantroline forms anintensively magenta-coloured complex with iron(II)-ions (there is no risk of bleeding from the indicatorbathophenantroline during the contact because theindicator is not water-soluble.)

Procedure:

– We have prepared small pieces of the indicator papers(containing bathophenantroline).

– The indicator paper has been dipped in distilled water(removing the excess water on a blotting paper).

– We have placed the indicator on the ink, covered itwith a piece of plastic foil and we have pressed itwith a finger for 30 seconds.

– The indicator paper was removed from the object.Magenta colour of the strip indicated the presence ofiron (II) ions.

5.2 Hydroxylamine hydrochloride spot test

Secondly, hydrolylamine hydrochloride has been usedto show the presence of iron (III)-ions in the ink.

Procedure:

– The test papers used for the bathophenantroline spottest have been cut in two pieces.

– A half of this test paper has been dipped inhydroxylamine hydrochloride.

– The hydroxylamine hydrochloride reduces the iron(III)-ions in iron (II)-ions and the test paper becomesmagenta.

The more iron (II)-ions and iron (III)-ions there are inthe paper, the more magenta coloured the test papersbecome.

6. ResultsThe indicator strips were used to evaluate the effects ofaqueous treatments on iron gall ink. The formation ofmagenta-coloured complex was not observed afteraqueous treatments involving large quantities of water,as is the case during washing or leafcasting. We canthus assume that some of the soluble iron(II) ions andiron(III) ions are washed from the paper.

In order to control the ageing stability of paper, wehave collected our results in tables (figure 6). A pictureis inserted in the table to report the area tested with thespot tests. After some years we will control if the ink isstill in good condition. By repeating the same tests onthe same areas we will be able to see if some solubleiron ions could be detected.

7. ConclusionIt was necessary for the workshop to find a rapid andsecure way to conserve and treat this enormous andimportant collection. Thanks to these simple spot tests,we can control the presence of free irons in the ink aftertreatment. And, as it is not water-soluble ink, we cansay that washing and leafcasting in this case is a goodsolution to treat this documents without damaging theink.

8. References1. F. F. Brentano, Catalogue des manuscrits de la Bibliothèque de

l’Arsenal, tome 9, Librairie Plon, Paris 1892.2. B. Reissland, Ink corrosion: side effects caused by aqueous

treatments for paper objects, Iron gall ink meeting, 4th and 5th

September 2000, The University of Northumbria, Newcastle,United Kingdom, 109–114.

3. V. Daniels, The chemistry of iron gall ink, Iron gall ink meeting,4th and 5th September 2000, The University of Northumbria,Newcastle, United Kingdom, 31–36.

4. H. Neevel, B. Reissland, Indicator Paper for Iron ions, documentfrom the Netherlands Institute for Cultural Heritage,Conservation research department, 27th November 2001,Amsterdam, Netherlands.

Figure 6: Tables of spot tests using bathophenantroline andhydroxylamine chloride.


INTEGRATED EFFORT FOR PAPER CULTURAL HERITAGEPRESERVATION IN THE SLOVAK REPUBLICJozef Hanus*1, Svetozár Katuščák2, Dušan Katuščák3, Vladimír Bukovský3, Jozef Rychlý4

1 Faculty of Chemical and Food Technology, Slovak University of Technology, Bratislava, Slovak Republic2 Slovak National Archives, Bratislava, Slovak Republic3 Slovak National Library, Martin, Slovak Republic4 Polymer Institute, Slovak Academy of Science, Bratislava, Slovak Republic


The principal tasks of archives and libraries – askeepers of irreplaceable source of cultural andinformation values – is to make accessible thesematerials for users and also to preserve this heritage forfuture generations. As paper is a principal informationcarrier and its degradation can cause the loss of“memory of mankind” only an integrated effort ofpaper education, research, science, conservation andpaper industry will be able to preserve this culturalheritage.1

The biggest problems in archives and libraries arecaused – paradoxically – by modern papers producedfrom the 2nd half of the 19th up to the recent years. Thenew technology of paper-making introduced in 1850,involved paper formation in an acidic environment.This was a crucial milestone from the point ofpermanence and durability of paper, its degradation andpreservation in archives and libraries. It is a self-degradative effect of acidic paper; “time bomb”, as it isoften called the limited lifetime of machine-made paperwith acidic rosin sizing with addition of alum has beenthreatening the great part of the cultural paper heritage.The present state of knowledge confirms that paperdegradation in the course of its ageing is the result ofhydrolysis (acidic, alkaline) and oxidation of celluloseby internal agents presented in paper in close co-influence of contaminated atmosphere, humidity andlight on one hand and cross-linking and fibresembrittlement on the other hand. Thermal, biologicaland mechanical destruction can occur as well. In mostcases, however, a combination of all above mentionedeffects causes degradation of cellulose macromolecule,hemicellulose and lignin which result in decrease offibres strength, mechanical properties, creation ofbrittleness, fragility and colour changes (yellowing,darkening) of paper.

1. Problem holders47 state archives in the Slovak Republic keep altogether22 345 archival fonds and collections representing totalscope of 157 700 running meters of material. Inarchives custody there are 44 236 middle-age chartersdating back before year 1526, 945 269 office books,about 138 000 maps, plans and drawings; documentsare stored in more than 1 million covers and boxes, etc.2

It is estimated that about 80–85% of total holdings are

documents created on paper from the period 1850–1970, i.e. on acidic paper with very law ageingresistance and thus potentially liable to self-degradationprocesses.3

Situation in Slovak libraries can be illustrated on anexample of the Slovak National Library in Martin. Thetotal number of book volumes until year 1900 is 1,2million, of which 684 000 are on acidic paper. Of900 000 volumes produced on hand-made paper470 000 ones are acidic – 117 500 volumes of them arein acute jeopardy. 300 000 volumes are produced onwooden paper; 214 000 volumes are on acidic paper –107 000 volumes are in acute jeopardy. Much worse issituation concerning books after year 1900. The SlovakNational Library keeps 2,4 millions of book titles ofwhich 2 280 000 are made of acidic paper. 1 140 000book volumes are in acute jeopardy.4 In other Slovaklibraries – scientific, public, special and academic – iskept about 43,6 millions of library units. On the basis ofstatistical data it can be stated that the situation in theselibraries is even worse because most of their collectionsare books, journals, newspaper and other unitsproduced after 1850 and 1900 on wooden and acidicpaper. It means that the distribution of library unitscompared to the Slovak National Library is shiftedmore to the period of “acidic paper production”.

From this brief review it is obvious that the situation incultural heritage preservation – of which archives andlibraries represent very significant and irreplaceablepart – is really very grave. It has to bear in mind thatpreservation of such heritage requires also considerablefinancial costs.

2. Problems solutionThere are two principal groups of problems to be solvedin paper preservation. The first solution must deal withacidic documents and books, i.e. acidic paper written orprinted in by different inks from the above mentionedperiod which create the majority of collections inarchives and libraries and are already kept in theseinstitutions. As the quantity of acidic books and recordsis enormous only mass-scale deacidification processeswill be able to solve the most serious problems. Variousmethods of mass deacidification treatment5 areavailable nowadays and an extensive applied researchstill continues in this field.


The second solution must deal with creation of newdocuments and books themselves. It is very obviousthat use of permanent and durable paper and writingand printing inks provides the best solution and theway, how to preserve paper cultural heritage of presentfor future generations.

3. Legislative provisionsPreservation and protection of cultural heritage all overthe world are covered by different legislative provisionson international and national levels. The SlovakRepublic belongs to countries in which legislativebackground provides an excellent base for preservation– worth of mentioning are at least the Declaration of theNational Council of the SR (NC SR) on preservation ofcultural heritage from February 2001, The Act of theNC SR no. 395/2002 on archives and registries and no.183/2000 on libraries.

4. National ProgramThe Department of Chemical Technology of Wood,Pulp and Paper covers in its educational programmealso problems of paper ageing and preservation;research activities in paper permanence and durabilitystarted at the Department already in 1980.6,7 During thelast years several diploma works – completed at thisDepartment and also at the Department of Graphic Artsand Applied Photochemistry – were devoted to pro-blems of preservation of cultural heritage – permanenceand ageing behaviour of some pulps and papers,deacidification of acidic paper, interaction of paper andprinting inks, their permanence and ageing resistance,etc. All these works were performed in closecooperation with the Slovak National Archives andLibrary.

The systematic effort of the authors started in 19898 andlater on of the organizations namely the SlovakNational Archives and the Slovak National Library forpreservation of archives and library paper culturalheritage together with activities of the Department ofChemical Technology of Wood, Pulp and Paper, STUBratislava and the Slovak Academy of Science resultedin the national programme and one particular project“Program of preservation, stabilisation andconservation of classical information carriers in theSlovak Republic – KNIHA SK”9,10.

The basic aims of the project can be summarized asfollows:

– increasing quality of university and continuingeducation of professionals for the field, includingengagement of graduate and postgraduate students ofchemical technology into projects on stabilisation ofLC carriers of information;

– concentration of the scientific capacity in the field oftechnology of preservation, stabilization and

conservation of lingo-cellulosic (LC) macromolecularmaterials in the Slovak Republic;

– creation of specialised shared national virtual libraryand inter-active shared knowledge space on theproblems of preservation of LC materials of theSlovak Republic for all project participants;

– improvement and verification of method forqualitative classification of endangered library &archives materials according to historical andtechnological criteria from the point of searching thepossibilities for increasing of capacity and decreasingof risks during their machinery treatment;

– new knowledge and new methods proposal forpreservation of library & archives materials;

– new information on indoor quality environment forlong-term storage of library & archives materials.

5. AcknowledgementsThe authors acknowledge the support of the ProjectKNIHA.SK granted by the Ministry of Education of theSlovak Republic and the grant VEGA 1/0061/03.

6. References1. J. Hanus, Integration of paper education, research and industry

for cultural heritage preservation. In: WPP ChemicalTechnology of Wood, Pulp and Paper. Editors: Baudin, G.,Fellegi, J., Gellerstedt, G., Katuscak, S., Pikulik, I., Paris, J.:Proceedings of the International Conference, September 17–19,2003, Bratislava, 91–95.

2. Informatívny sprievodca štátnych archívov Slovenskej republikyI. Ministerstvo vnútra SR, OA SS, Bratislava (2000).

3. J. Hanus, J. Mináriková, E. Hanusová, Deacidification withoutequipment and money – dream or reality? ICOM-CC 13th

Triennial Meeting, Rio de Janeiro 22–28 September 2002,Preprints (Volume II), ed. Roy Vontobel, James & JamesLondon, 603–608.

4. V. Bukovský, Nevyhnutnosť masovej deacidifikácie papiera vofondoch knižníc a archívov, Buničina a papier – technológie,vlastnosti, životné prostredie. Zborník z medzinárodnejkonferencie. Bratislava, 2001, 183–188.

5. H. J. Porck, Mass deacidification: An Update of Possibilitiesand Limitations, European Commission for Preservation andAccess, Amsterdam, Commission for Preservation and AccessWashington D.C., 1996.

6. P. Krkoška, K. Vizárová, Stálosť a trvanlivosť niektorýchbuničín a papierov, Buničina a papier – technológie, vlastnosti,životné prostredie. Zborník z medzinárodnej konferencie.Bratislava , 2001, 171–178.

7. J. Hanus, Štúdium starnutia papiera z hľadiska ochranyarchívnych dokumentov, Kandidátska dizertačná práca, CHTFSVŠT Bratislava, 1987.

8. S. Katuščák , J. Hanus a kol.: Veľkokapacitná stabilizácia akonzervácia klasických nosičov informácií. (Increasing Capacityof Stabilisation and Conservation of Traditional Carriers ofInformation). In Slovak, Res. Report State Forest Froducts Res.Institute. SDVÚ 26/89, Bratislava 1989.

9. S. Katuščák S, Chemical Technology of Wood, Pulp and Paperin Culture, Education and Industry. In: Baudin G., Fellegi J.,Gellerstedt G., Katuscak S., Pikulik I., and Paris J. (Editors):WPP – Chemical Technology of Wood, Pulp and Paper. 490pages. ISBN 80-227.1942-0. STU Bratislava 2003.

10. V. Bukovský, D. Katuščák, J. Hanus, Program ochranypapierových nosičov informácií v SR, Buničina a papier –technológie, vlastnosti, životné prostredie. Zborníkz medzinárodnej konferencie. Bratislava, 2001, 179–182.


CHARACTERISATION OF INK COMPONENTS IN ANCIENTMANUSCRIPTS USING FTIR SPECTROSCOPYNúria Ferrer1, M. Carme Sistach2

1 Scientific Technical Services, University of Barcelona. c/ Lluís Solé i Sabarís s/n. 08028 Barcelona, Spain2 Arxiu de la Corona d’Aragó, c/ Almogŕvers,77. 08018 Barcelona, Spain


1. IntroductionDegradation of paper and parchment has long been aline of scientific research because of the destruction itcan produce in libraries and archives. Serious damagecan be caused by iron gall inks.

Different parameters seem to be involved in thedestructive process: paper characteristics, inkcomposition, and other compounds.

Knowledge of reaction mechanisms in original inkcomponents is crucial to understand the damage causedto paper and parchment1-6. Therefore, characterisationof final ink products may help us to understand betterthe mechanisms and consequently to avoid degradation.

Considering ink components (tannins, iron sulphate andgum Arabic) as natural products which containimpurities, it is reasonable to find several inorganicelements (Cu, K, Zn ..) together with iron. In the sameway carbohydrates from tannins and gum Arabicdevelop an important role when oxidation andhydrolysis processes affects to the ink, as well as thepaper support itself.

FTIR spectroscopy was used to characterise inkcomponents in ancient manuscripts.

One of the most important problems related to this kindof samples is the small amount of ink that may beremoved from original manuscripts. This is whymicroscopic techniques are required.

Different methodologies have been used in order toobtain good quality infrared spectra. Reflectiontechniques, such as attenuated total reflectance (ATR)and transmission techniques have been compared. Bothmethodologies are coupled to an IR microscope, due tothe usually tiny amount of ink contained onmanuscripts. For transmission techniques, we need toremove some particles from the surface of inks with atungsten needle, and transport them to a diamond cell.At the same time, it is necessary to try to avoid paper orparchment. ATR techniques are not destructive at all.The ZnSe crystal of the objective is pressed against thesample and a single reflection penetrates it slightly.

The technique was tested using several manuscriptsamples with ink, which show different degree ofcorrosion, blackness and amount of settled ink.

A large number of inks have been analysed anddifferent oxalate salts have been characterised. Goodcorrelation between acidity of ink and oxalate anions

has been observed. Iron (II) sulfate has also beendetected in some samples.

2. ApparatusA Bomem MB-120 infrared spectrometer was used.The instrument has a Glowbar source, a KBrbeamsplitter and a DTGS detector. A Spectra-tech IRPlan Microscope, which has a liquid nitrogen cooledMCT detector and an ATR objective of ZnSe, isattached to the spectrometer.

Transmission infrared microscope spectra weremeasured by accumulating 100 scans at a resolution of4 cm-1. ART infrared spectra were measured byaccumulating 200 scans at a resolution of 8 cm-1.

Spectral range was from 4,000 to 720 cm-1. The spectraldata were processed with the GRAM/386 program fromGALACTIC.

3. ResultsBoth methods used in this study, transmission andreflection techniques, give the same information and areequally useful for all samples analysed. Poor qualityspectra are usually obtained when non-degradedsamples of paper are measured with the ATRmicroscope. Usually, several attempts have to be made,because the crystal often touches a non-smoothedregion containing fibres and empty areas. As degradedink samples have a bigger and more homogeneoussurface, the ATR spectrum is normally easier to obtain.

Figure 1: An image of one of the samples used in ourresearch, where the corrosion effect can be seen.


Spectra of inks on parchment are normally bettersamples to analyse than on paper, whether removingparticles for the transmission method or pressing theATR crystal.

These results mean that the ink composition is thesame, not only on the surface but also in the region incontact with the paper support.

Distribution of iron in the paper involves iron (II) andiron (III) ions, which can be found as differentcompounds in the ink spectra. In the same way, calciumfrom the paper alkaline buffering remains in the sampleas calcium carbonate, calcium sulphate or calciumoxalate. Inks from parchment show more contributionof this calcium compounds. Degradation of naturalextracts of tannins and gum arabic brings about organicsalts. Although spectra of inks have important bands ofwater and iron sulphate that overlap other compounds,it was possible to identify bands placed in free zones. (samples were cover with carbon and analysed on

surface).

Several samples analysed by GC-MS showed oxalicacid in their composition.

4. ConclusionsFTIR allows a rapid analysis of samples of ink on paperor parchment, using both transmission and reflectionmicroscopic techniques.

According to the sample’s pH, corrosion and colour,different compounds are detected in the ink. Calciumoxalate, calcium carbonate, iron sulfate, iron oxalateand iron potassium oxalate were identified.

These findings contribute to a better understanding ofthe mechanisms of the reactions involved in inks andinks’ degradation.

5. References1. B. Reissland, Visible progress of paper degradation caused by

iron gall inks, Postprints The iron gall ink meeting 4-5 set 2000,Northumbria University, Newcastle upon Tyne, 2000, 67–72.

2. M. Strlič, J. Kolar, V. S. Šelih, D. Kocar, B. Pihlar, Acomparative study of several transition metals in Fenton-likereaction systems at circum-neutral pH, Acta Chim. Slov., 2003,50, 619–632.

3. M. C. Sistach, N. Ferrer, Fourier Transform InfraredSpectroscopy applied to the analysis of ancient manuscripts,Restaurator, 1998, 19, 173–186.

4. M. C. Sistach, N. Ferrer, Iron gall ink corrosion in manuscripts,Post prints The Iron gall ink meeting 4-5 set. 2000. NorthumbriaUniversity, Newcastle Upon Tyne, 2000, 73–81.

5. G. Kolbe, Gelatine in historical paper production and asinhibiting agent for iron-gall ink corrosion on paper,Restaurator, 2004, 25, 26–39.

6. S. Margutti, G. Conio, P. Calvini, E. Pedemonte, Hydrolytic andoxidative degradation of paper, Restaurator, 2001, 21, 67–84.

7. M. C. Sistach, J. M. Gibert, R. Areal, Ageing of laboratory inksStudied by Reflectance Spectrometry, Restaurator, 1999, 20, 151–166.

Figure 2: Transmission spectrum of a parchment samplefrom the XIIIth century: Calcium oxalate and calciumcarbonate can be measured on the surface of the ink.

There seems to be a correlation between pH and colour,changing from black, dark to light when pH increases7

(Surface pH measurement, TAPPI T 529 om-99).

Corrosion also changes from very strong corrosion atvery low pH to strong corrosion, poor corrosion and nocorrosion when pH increases.

Comparing the oxalate salts with these results above,we can see that iron potassium oxalate appears at lowpH values, from 2.5 to 6.2. Higher pH values, from 6.5to 6.7, clearly indicate calcium oxalate, even thoughthis salt coexists with iron potassium oxalate and ironoxalate in some samples.

Calcium oxalate seems to be related to samples with nocorrosion and higher pH values.

In general, big peaks of K and Fe using SEM-EDX(JSM 840 (Jeol Ltd.) with Scanner AN 10000 (LYNKSYSTEMS) with Be window) confirm iron potassiumoxalate. Big peaks of Ca correlate with calcium oxalate

Figure 3: (SEM-EDX) spectrum of inorganic elements in theink.


Investigation on iron-gall inksHana Paulusová*1, Jiří Karhan2

1 State Central Archives in Prague, Czech Republic2 Czech National Bank, Prague, Czech Republic

* corresponding author: e-mail: [email protected]

In restoring some paper manuscripts at the State CentralArchives in Prague, a number of species, which wereclearly visible under a stereomicroscope and whoseorigin was not known, were found on the surface oflines of iron-gall inks. Available spectral analyticalmethods – Raman spectroscopy, FTIR and X-rayfluorescence – were employed to investigate thesespecies.

On the basis of the results of the analyses, these speciescan be divided into two groups: The first group consistsin crystalline products formed directly on the surface ofthe iron-gall ink. The second group consists in foreignsubstances that were most probably introduced to theink lines as a blotting powder used by the writer.

The first group includes crystals formed directly in theink line. They can grow to a size of up to several tenthsof a millimetre. They occur in very corrosive inks andare mostly found in the inner parts of the book block(where the measured pH is in the range 2–3). Theyprobably require a favourable microclimate for theirgrowth. The crystals are mostly white, or slightlyyellow or brownish. Information on crystal formationsappears only sporadically in the literature, frequently inconnection with deacidification processes. Historicalinks have been found to contain, e.g. calcium ormagnesium sulfates or oxalates,1,2 after deacidificationcarbonates too.3-5 A manuscript with one type of iron-gall ink, where numerous crystals were found, wassubjected to spectral analysis (Land Rolls 27, 1651,D22). The chemical composition of the crystals wasstudied using X-ray fluorescence microanalysis andFTIR. It was found that the crystals contain calcium andphosphorus. FTIR indicated that an organic phaseparticipated in their formation, where the calcium saltof an unspecified organic acid was identified. On thebasis of the results obtained by FTIR, it is apparent thatthe crystal formations do not consist of a singlecompound, but rather of a mixture of several products(a crystalline protein was also identified). More detailedstudy was prevented by the very small amount ofmaterial available for the analyses. The crystals aremost probably formed as a consequence of

degradation processes of the cellulose fibres due theeffect of the corrosive ink.

In addition to salt formations, some inks alsosporadically contained flat sparkling particles ofirregular shape, which looked reddish under themicroscope. Archivists were of the opinion that thesecould be gold flakes that could have been intentionally

mixed in the ink. It was found by X-ray fluorescenceanalysis and FTIR that this is an amorphous,transparent substance in which very fine red particlesare scattered, which were identified as ferric oxide onthe basis of the Raman spectra. No connection with thecorrosive ink has been found.

In restoring a number of manuscripts of the StateCentral Archive in Prague (Fund of the Upper MiningOffice in Jáchymov, Book No. 831 of 1753–1883,Book No. 832 of 1784–1820) and the State RegionalArchives in Prague (Kováň 1, register of births anddeaths of 1723–1765), a mixture of coloured particleswas found in the sections of the books and ink lines,which can be classified in the second group on the basisof their character. Blue particles predominated and werefound in mixtures with black, grey or white ortransparent particles. As the presence of these mixtureswas repeated in a number of books and the amountswere not negligible, their elemental composition wasfound using X-ray fluorescence microanalysis.

Table 1: Elemental composition of the analysed particles.

Type of solid particle Elemental compositionBlue glassy particles Si, K, As, Ca, Fe, Co, Ni, Cu,

ZnBlack particles (type I) Pb, trace amounts of CaGrey particles Zn, trace amounts of FeBlack to brown-black (type II) Zr, Nb, Si, Sn, Ca, Ti, Mn, Fe,

WWhite to transparent particles Si, small amount of Ca

The blue particles were identified (also using an opticalmicroscope) as blue potassium glass, which was alsofound in other studied manuscripts. Because of thearsenic content, it can be assumed that the source of thecobalt for production of the glass is saflorite (CoAs2),which occurs in various veins together with nickel, orsmaltine (CoAs3) or cobaltite (CoAsS). These mineralsare found in Bohemia in the Krušné Mts. Because ofthe relative contents of cobalt and arsenic in the glass,smaltine seems most probable. The light particles,which consist practically only of silicon dioxide, wereused in the form of fine sand to blot the wet ink. Theother types of particles have not yet been preciselydefined; if a sufficiently large sample of material isavailable, it will be employed for identification by X-ray diffraction.

An Eagle µProbe X-ray fluorescence spectrometer wasused to study the elemental composition of the particlesin the historical ink. In this connection, it is useful to


point out the ability of the spectrometer to carry outnon-destructive distribution elemental analysis, whichcould also be interesting for study of corrosion of inks.

This application permits monitoring of the elementaldistribution either along a line (LineScan) or on asurface (Mapping). The scanning technology designatedas mapping has the great advantage that three kinds ofinformation can be obtained from the measured area:the elemental composition at any point indicated by thecursor on the measured surface, the elementalcomposition on a line of any length and orientation onthe surface, and the elemental composition over arectangular area of any size or location (the maximumsize is given by the size of the measured area). Specialsoftware enables the creation of spectral maps(pictures), in which it is possible to depict thedistribution of a pre-selected element in the frameworkof the measured area, where the magnitude of theintensity of the fluorescent radiation of this element isexpressed either through various intensities on a greyscale from black (minimum) to white (maximum) orcoded in a coloured scale. Thus, a single measurementof the surface of a sample can yield the spectral mapsfor the individual elements and direct information notonly on the distribution, but also on the concentrationsof the given element over the surface.

The poster depicts the analysed crystal formations inthe inks and foreign material present in the ink lines,accompanied by a brief description of the studiescarried out. The poster is supplemented by depiction ofthe distribution of elements in historical inks in theform of spectral maps.

We would like to thank Ing. Miroslava Novotná, CSc.for the FTIR analysis and Raman spectroscopy andDoc. Ing. Martin Maryška, CSc. for optical microscopeimages (Institute of Chemical Technology in Prague).

References1. B.Reissland, Neue Restaurierungsmetoden für Tintenfraß auf

Papier mit wäßrigen Phytatlösungen-Möglichkeiten undGrenzen, in: G. Banik, H. Weber, Eds., Tintenfraßschäden undihre Behandlung, W. Kohlhammer Stuttgart, Germany, 1999,113–219.

2 J. G. Neevel, B. Reissland, The Ink Corrosion Project at theNetherlands Institute for Cultural Heritage – a review, in:Proceedings European Workshop on Iron-gall Ink Corrosion,Rotterdam, Netherlands, 1997, 37–45.

3. M. Hey, The Deacidification and Stabilization of Irongall Inks,Restaurator, 1981, 1–2, 24–44.

4. C. Barry, J. Fields, A Examination of Iron Gall ink drawings inthe British Museum deacidifiied with barium hydroxide, in: A. J.E. Brown, Ed., The Postprints of Iron Gall inks meeting, TheUniversity of Northumbria, Newcastle, UK, 2001, 83–88.

5. B. Reissland, Ink corrosion :side effects caused by aqueoustreatments for paper object, in: A. J. E. Brown, Ed., ThePostprints of Iron Gall inks meeting, The University ofNorthumbria, Newcastle, UK, 2001, 109–114.


NEW EVALUATION METHODS OF PAPER DETERIORATION: STUDYOF BRITISH PARLIAMENTARY PAPERS IN THE COLLECTION OFNATIONAL MUSEUM OF ETHNOLOGY, JAPANNaoko Sonoda*1, Shingo Hidaka1, Tsuneyuki Morita1, Takayuki Okayama2, Hajime Ohtani3, MasazumiSeki4, Katsuhiko Masuda5, Masako Kanayama6, Satoko Muramoto7

1 National Museum of Ethnology, Osaka, Japan2 Tokyo University of Agriculture and Technology, Tokyo, Japan3 University of Nagoya, Nagoya, Japan4 Kochi Prefectural Paper Technology Centre, Kochi, Japan5 Showa Women’s University, Tokyo, Japan6 Gangoji Institute for Cultural Properties, Nara, Japan7 National Diet Library, Tokyo, Japan


The National Museum of Ethnology, Osaka, Japan,received in 1998 a donation of approximately 13,000volumes of British Parliamentary Papers from KyoceraCo. Ltd, on the condition that they be made available toresearchers. However, due to the fragility of paper,perusal of a part of these papers is either very difficult orimpossible. We are conducting research to elucidate atwhat stage of damage we have to start a strengtheningtreatment. In other words, how can we evaluate the stateof paper deterioration? Only when these points are clari-fied, we can select an appropriate strengthening method.

In the first part, the present condition of the BritishParliamentary Papers is summarized. This investigationhas been conducted on samples from 47 Papers.

In the second part, our ongoing research to find outappropriate testing methods to evaluate the state ofpaper deterioration is presented. This study has beenconducted on 9 samples of discarded books from theNational Diet Library.

1. Present condition of the BritishParliamentary Papers

The double fold test has been carried out on each of 47of the Papers, selected from different periods. Thecomposition and degree of deterioration of papers havethen been examined using small pieces of paper,detached during a double fold test.

Most of samples from the first half of the 1800s arecomposed of linen and those from the last half of thecentury showed an increased ratio of esparto as well asan addition of cotton rag, Manila hemp and groundwood pulp. Softwood chemical pulp began to appeararound the 1880s and became the mainstream materialby the 1900s. Samples from the time of World War IIshowed a great portion of non-wood fibres. Samplesafter World War II showed the use of softwood andhardwood chemical pulp (Figure 1).

Zero-span tensile strength (Figure 2) shows the strengthof one fibre. Results of a measurement of Zero-span

tensile strength indicate that, on the whole, the samplesof paper from the first half of the 1800s are comparati-vely strong, while those from the last half of the 1800sto the first half of the 1900s tend to be comparativelyweak. As the analysis of fibre composition shows, theuse of ground wood pulp may be a cause of deterio-ration in the papers of this period.

2. Evaluation of deterioration of paper fromdiscarded books

2.1. Visual evaluation

The year and country of publication and fibrecomposition of natural aged discarded books aresummarized in Table1.

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Table 1: Year and country of publication, and fibrecomposition of studied books.Sample Date and Fibre composition

countryof publication

A 1942, Japan Groundwood pulp(70%),softwood sulfite pulp(30%)

B 1952, Japan Groundwood pulp (75%),softwood sulfite pulp(25%)

C 1918, Japan Groundwood pulp (40%),softwood sulfite pulp (40%),cotton rag (20%)

D 1943, Japan Groundwood pulp (85%),softwood sulfite pulp (15%),cotton rag (trace),unknown (trace)

E 1949, Japan Groundwood pulp (65%),softwood sulfite pulp (35%),unknown (trace)

F 1943, Japan Groundwood pulp (25%),softwood sulfite pulp (75%),straw (trace)

G 1949, Japan Groundwood pulp (80%),softwood sulfite pulp (20%)

H 1948, Japan Groundwood pulp (85%),softwood sulfite pulp (15%)

I 1932, Mexico Groundwood pulp (50%),softwood sulfite pulp (45%),cotton rag (5%)

Visual evaluation was first conducted from a restorationstandpoint. A restorer has been asked to group booksamples into 3 classes: samples which necessitateconservation treatment, samples which do notnecessitate conservation treatment, and intermediatesamples.

In addition to performing the conventional double foldtest, we devised a new evaluation method that wetentatively call the rolling test, using cylinders ofdifferent diameter: from 40 mm to 5 mm in diameter,with an interval of 5 mm. According to this method, apaper is first rolled around a cylinder of 40 mm indiameter. If the page is rolled safely, without wrinkles,tears or any kind of resistance, the same test isperformed using a narrower cylinder, and so on. Assoon as a sign of resistance appears, the rolling test wasstopped. This test was done in two different manners:rolling parallel to the page (from 40 mm up to 10 mmin diameter), and rolling from a corner forming anangle of 45 degree to the page (from 40 mm up to 5 mmin diameter) (Figure 3). See Table 2 for results.

2.2. Pyrolysis Gas Chromatography (PyGC)

If a paper sample is pyrolysed at 300 oC, it decomposesslowly, generating levoglucosan as the main decompo-sition product. However, deteriorated samples frompaper I (Table 2) are quickly thermally decomposedeven at 300 oC. In addition to levoglucosan, its oxidizedproduct levoglucosenone was clearly observed. Thisresult suggests that the oxidation of cellulosecontributes greatly to the deterioration of paper.

Comparing the pyrograms of samples taken from themiddle of a paper with those of samples from the edgesof the same page (3.5 cm and 7 cm from centre, and atthe extreme end of the page), we found that the peak oflevoglucosenone was relatively much higher at theedges (Figure 4).

3. SummaryDeterminations of mechanical properties, by zero-spantensile strength performed on detached pieces of 47 ofthe British Parliamentary Papers might have given morealarming results than if they had been performed on awhole page. Nevertheless, the results illustrate well theoverall present paper condition.

To evaluate if a book requires a conservation treatment,the state of degradation of an entire page is taken inconsideration. We believe that the rolling test is aneffective one for visual evaluation and deserves furtherattention, as it can be carried out on a larger surface ofthe page, and is much less destructive than a doublefold test. The data in Table 2 seem to indicate that (withthe exception of sample B) if a paper cannot be safelyrolled around a cylinder of 20 mm in diameter, itrequires precaution during handling.

The PyGC is also effective for evaluation of paperdeterioration. By using the relative peak areas of

Figure 3: Rolling test method. Left: rolling from a corner atan angle of 45 degree to the page. Right: rolling parallel tothe page.

Table 2: Results of sample evaluation.Conservation Double Rolling Rollingtreatment fold test test

test (parallel) (45 deg)Sample A intermediate 2 * **Sample B not necessary 1 25 mm 40 mmSample C not necessary 2 * 15 mmSample D intermediate 1 10 mm 20 mmSample E necessary 0 25 mm 25 mmSample F not necessary 2 10 mm 5 mmSample G intermediate 2 * 5 mmSample H necessary 0 20 mm 30 mmSample I necessary 0 25 mm 30 mm* No change even with a cylinder of 10 mm in diameter.** No change even with a cylinder of 5 mm in diameter.


levoglucosan and levoglucosenone as an index, a rapidevaluation of the degree of deterioration of paper seemspossible using a tiny sample, without damaging theoriginal.

4. References1. T. Okayama, K. Fukai, K. Kanamori, M. Seki, N. Sonoda, T.

Morita, Degradation of the British Parliamentary Papers andStrengthening Using Cellulose Derivatives (in Jap), Abstracts ofthe 23rd Conference of the Japan Society for the Conservation ofCultural property, 2001, 36–37.

2. H. Ohtani, Y. Taguchi, N. Sonoda, Evaluation of Degradation ofAcid Paper Using Pyrolysis Gas Chromatography (in Jap),Abstracts of the 35th Annual Meeting of Union of Chemistry-Related Societies in Chubu Area, Japan, 2004, 224.

Figure 4: Pyrograms of (a) filter paper (reference), (b)deteriorated paper (centre), (c) deteriorated paper (3.5 cmfrom centre), (4) deteriorated paper (7 cm from centre), and(e) deteriorated paper (edge). Pyrolyzer: Frontier Lab PY-2020D, pyrolysis temperature: 300 oC, gas chromatograph:HP6890, column: Ultra ALLOY ±5, oven temperature, 50 oC– 5 oC/min – 280 oC, detector: flame ionization detector,injection temperature: 280 oC, detector temperature: 300 oC,sample weight: ca. 300 µg.