Introduction

Iron gall ink was the ink of choice for centuries in

western history. Its chemical instability has caused

a major threat to paper-based heritage. From the

perspective of long-term storage of archival

collections, this research focuses on the following

research question:

Can the synergistic effects of deteriorating agents

for paper containing iron gall inks that have been

identified in literature [1, 2], i.e. temperature,

relative humidity, iron(II) content, pH of ink lines,

paper grammage, and intensity of application be

quantitatively determined through theoretical,

experimental and statistical analysis?

Damage Function for Paper Containing Iron Gall Inks

Yun LiuUCL Institute for Sustainable Heritage, University College London, London, UK

yun.liu.14@ucl.ac.uk

Fig. 1 A manuscript damaged by iron gall ink corrosion (Credit: The National Archives, Kew, UK).

Methodology

Damage Functions in heritage science are

functions describing detectable physical or

chemical change in the context of value [3].

fDamage = fValue (fChange (x))

Where fChange =Δ𝐶ℎ𝑎𝑛𝑔𝑒

Δ𝑡

= f (environmental factor, material property)

References[1] Kolar, J., Stolfa, A., Strlič, M., Pompe, M., Pihlar, B., Budnar, M., Simcic, J., Reissland, B., 2006. Historical iron gall ink containing

documents — Properties affecting their condition. Analytica Chimica Acta 555, 167–174.

[2] Neevel, J.G., 1995. Phytate: A Potential Conservation Agent for the Treatment of Ink Corrosion caused by Iron Gall Inks.

Restaurator 16, 143–160.

[3] Strlič, M., Thickett, D., Taylor, J., Cassar, M., 2013. Damage Functions in Heritage Science. Studies in Conservation 58, 80–87.

AcknowledgementsThis project is supported by the EPSRC Centre for Doctoral

Training in Science and Engineering in Arts, Heritage and

Archaeology at University College London, in collaboration

with the Smithsonian’s Museum Conservation Institute, the

National Archives and the company Lichtblau e.K.

Expected Outcomes

The damage function to be developed for paper containing iron gall inks will be used to predict the fitness for use of iron gall ink collections based on

their current material state, in order to prioritize controllable environmental parameters. This will be a major contribution to the development of the online

collections modelling tool that will facilitate collection management via visualised data interpretation and collection management scenario exploration.

Fig. 4 Viscometric method

for DP determination.

Fig. 3 Cold extraction

method for pH

determination.

Fig. 2

Bathophenanthroline

test for Fe2+ identification.

Historical Iron Gall Inks typically contain tannic acid and iron(II) sulfate as

colour-forming components, as well as Arabic gum as the binder. Degradation

of inks results in a colour change of inks from blueish-black to brown as well as

loss of mechanical properties of paper support along ink lines in extreme cases.

Tannic acid extracted from gall nuts Gallic acid

+ H2O + Fe2SO4·7H2O

Insoluble

Fe(III)

gallate

complex

+

Arabic gum Ink

solution

Environmental Parameters

Material Properties

Paper Properties

Ink Properties

Dose-response Function

Damage Function for Paper Containing

Iron Gall Inks

Threshold Based on Value

Temperature

Relative Humidity

Grammage

pH of Ink Lines

Application Intensity

Iron ContentRate of Degradation

Degree of Polymerization (DP)

Physicochemical Approach

Epidemiological Approach

Non-destructive Collection Survey

Damage Function for Other Materials

User Control

Defined Input and Output

Online Collections Modelling Tool

Doctoral ResearchMRes Research

Psychophysical Approach

Model Validation

Experimental Approach

Theoretical Approach Theoretical FunctionArrhenius Equation

Ekenstam Equation

Testing Techniques Fig. 6 Data for modelling

were obtained from historic

samples using NIR

spectrometer in

collaboration with the

National Archives (UK).

Fig. 5 Thickness

measurement. 2 3 4 5 6

Milestones Experimental Parameters