scienceinaidofexpertopinion (published version)

M. Ioannides et al. (Eds.): EuroMed 2012, LNCS 7616, pp. 874–883, 2012. © Springer-Verlag Berlin Heidelberg 2012

Science in Aid of Expert Opinion: A Tell-Tale on Disputed Artworks

Fotini Koussiaki1,4,*, Vivi Tornari2,4, Eleni Kouloumpi3,4, and Alkis Lembessis4,5

1 Conservation and Restoration of Cultural Heritage, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece

[email protected] www.arch.auth.gr

2 IESL/FORTH, Institute of Electronic Structure and Laser, N. Plastira 100, Heraklion 71 110, Crete, Greece

www.iesl.forth.gr 3 National Gallery - Alexandros Soutzos Museum,

Michalakopoulou 1, Athens, Greece www.nationalgallery.gr 4 ARTGNOMON

www.artgnomon.com , 5 TAURUS Secure Solutions LtD, Pipinou 22, 11257 Athens, Greece

www.taurus.com.gr

Abstract. Nowadays the increase demand for loaning art objects as well as safety, ethical, economical and security issues, are forcing curators and conservation experts to undertake challenging and disputable decisions in regards of issuing an artwork accreditation. On the other hand scientific analysis and modern tools in artwork conservation offer a powerful source for objective multidisciplinary choices serving and safeguarding an expert’s decision. Hence, strong initiatives and innovative actions are important to be taken to ensure that modern technology serves for cases of dispute, damage, fraud, or mistreatment during transportation of Cultural Heritage. Therefore the paper presents some current results in originality assessment and results from the development of an anti-fraud concept based on an innovative approach of works of art, and application of methodologies and instrumentation. The authors’ aim and prior consideration is to respond to such critical aspects of increased importance in cultural heritage preservation, among which to secure proper treatment, to assess possible damage and to fight fraud actions. The paper introduces for the first time to our knowledge the idea of fraud-fighting with development of dedicated “ultimate documentation UD” ™.

Keywords: accreditation, art conservation, art in transit, documentation, originality, interferometry, holography, spectroscopy, conservation science, originality, security, fraud, titanium white.

1 Introduction

Europe holds universal importance in worldwide Cultural Heritage and transit of works of art, such as paintings and sculptures, which are the lifeblood of Europe's * Corresponding author.

Science in Aid of Expert Opinion: A Tell-Tale on Disputed Artworks 875

cultural communication. Museums put them on display and, recurrently, loan them out to other institutions [1]. However, sale or exhibiting art and moving it from place to place cause problems. Repeated handling and exposure to sudden environmental and climatic changes can all take their toll on old and delicate objects increasing the need for conservation treatments. Art in transit is also under threat from inadequate transportation, mishandling and fraud [2]. Distortions of structural and mechanical properties of artworks are an important factor of deterioration causing slow but steady disintegration of the artwork [3, 4]. The thermal and moisture related degradation processes, transportation and handling, various conservation and restoration actions, as well as the display and arrangement may systematically or rapidly influence the condition of the concerned artwork, monument or antique. Chemical attack, chemical disintegration, pollutants and dust particles are common enemies of the structural and chemical integrity.

Conservators need to monitor the condition of artwork in a way that responds to these issues. Laser technology is among the most competitive candidates for remote full-field non destructive examination of extended delicate surfaces [5]. Moreover a novel tool to help conservation researchers and practitioners to visualize the invisible defects, enduring disintegration processes and interventions has been introduced through the principles and targeted adaptation of holographic interferometry [6-12].

The “ultimate documentation UD” ™ concept was developed to aid the expert decision on disputed issues, such as in the case of deterioration that could signify either mistreatment or intervention and/or cases that a fake is presented claiming to be genuine artwork, and/or cases that provenance or tracking of masterpieces is requested. It utilizes novel scientific approaches based on technology advances offered by exploiting and providing to the expert the innovative tools for a secure and sustainable preservation and originality id of precious artworks.

Thus “ultimate documentation UD”™ may apply in many strategic decisions implemented by systematic documentation update. These range from a routine seasonal examination of a work’s state of preservation, to its deterioration control and definition of early-induced damage, as well as periodic assessment of conservation treatments and materials compatibility, continuous monitoring of transportation impact, direct confirmation of originality and control of maintenance for any art object in transit, likewise tracking of masterpieces and archaeological findings, etc.

The effectiveness of the proposed method relies on the direct coded extraction of distinct features from the artwork in the lane of conservation, transportation and loan that characterizes the state of conservation of the artwork and its originality. The coding and decoding of such characteristic features once performed can then be performed at any, before and after, instant since they have been optically and numerically transformed for digital archiving. The artwork’s features or the archived coded data forming the “artwork id”, commonly known as fingerprint, can be compared periodically or at any later time to provide indication or evidence of induced alterations leading any art expert to safe conclusions. The UD™ advances the state of the art and its elaboration in synergy with existing methods and practices may lead in universal application and worldwide exploitation.

876 F. Koussiaki et al.

2 Methodology Concept of UD™

The fact that experts do not always agree on the authenticity of a particular item makes the matter of “provenance” more complex. Conventionally, a work comprised in an artist’s “catalogue raisonné” has been the key to confirming the authenticity, and thus value {2}. Omission from an artist’s catalogue raisonné indeed can be proved fatal to any potential resale of a work, notwithstanding any proof the owner may offer to support authenticity. Art forgery can be extremely lucrative; in addition, art specialists lack many of the important technological means that scientists use to authenticate art today. Modern dating and analytical techniques have made the identification of forged artwork possible. This is essential in order to be conscious of illegitimate trade of art and antiquities, as well as for the protection of our cultural heritage.

The contribution of science and technology in the service of art is essential. We are in position to collect valuable information for each and single artifact operating mostly in a non-destructive, non-contacting and not-interventive manner. Technology advances in chemical, structural and spectroscopic analysis are superior remote methods which offer the high potential in UD™. The UD™ methodology scheme is shown in the table I.

Table 1. Ultimate Documentation database scheme

Ultimate Documentation database scheme 1 Total

artwork elements

TAE

2 Characteristic

features CF

1. Whole information 2. determination of data 3. features extraction 4. total data 5. useful data 6. interconnection of data

3 TAE+CF+A

Scaling characteristic features A 4 TAE+CF+A+B

Scaling characteristic features B

5 TAE+CF+A+B-(C)

Testing characteristic features CxD

6 TAE+CF+A

+B-(C)x(D) The combination of techniques and the interconnection of unique information

sources ranging from analytical techniques up to the laser applications, can contribute to the re-synthesis of the artists’ palette, revealing thus the first steps of a painting’s creation. With the application of a complete analytical study, the full characterisation


of materials and artistic construction techniques can be achieved along with the recording of the preservation state of the object. As far as the contemporary artefacts are concerned, their dating can be achieved through a combination of techniques which offer complementary information and can place a work of art into a specific chronological period. Even though there is no technique able to give a construction date, there are techniques which can determine the period of production, through a) the macroscopic study (characterisation of a technique as traditional or not), b) the structural study revealing hidden information in terms of mechanical discontinuities and defects, c) imaging techniques at various wavelengths of the electromagnetic spectrum (detection of invisible elements such as under-drawings, signatures), d) the study of the stratigraphy (way of construction and detection of overpaintings), e) identification of materials (some pigments and binding media were discovered and used at a specific period), and f) combination techniques to assess degree of deterioration (the ageing degree of a material). Thus the documentation is a long process made along analytical steps integrated in a coded form in a fully secure database forming the UD database of each and single artwork [6].

3 Proof of Principle

In the presented research study the feasibility of the methodology of UDTM is shown through a known exemplary case of the research group, the painting attributed to the famous Greek painter Konstantinos Parthenis (1878-1967), “Still life before the Acropolis” shown in figure 1.

Fig. 1. In a) Painting attributed to Parthenis “Still life before the Acropolis” with areas of recording and in-situ analysis and b) reverse of canvas

In figure 1 are shown the areas analysed during in-situ measurements. No sample was removed from the paint surface. From the reverse side of the painting only three microsamples were collected. These were taken from areas at the side of the canvas next to the stretcher. The painting was disputed in regards to the originality of Parthenis or not. The research group approaches the scientific research of artwork in order to acquire its UD™ aiding the expert identification process and reveal dispute, through two main study phases: The first phase comprises of in-depth but general examination with conventional and alternative tools. This includes the stereoscopic examination of the surface, examination at specific wavelengths with the use of multispectral imaging


system, structural examination of surface and subsurface or bulk, and finally depending upon case sampling and study of the cross-sections under the optical metallographic microscope in combination with the use of micro-chemical tests. This general approach can offer very important information about the preservation state of the object, as well as the construction technique used by the artist. The second phase consists of an in-depth specialized approach. This phase of research as in the Parthenis case shown takes place when there are indications requiring the use of specific instrumental techniques in order to answer questions born at the first phase of the study. The results of the first phase along with the type of information that has to be collected are the ones determining the choice of the next steps of documentation and in particular the analytical techniques. The employed methods give accurate information concerning the chemical type of the construction materials of the works of art. In order to collect the requested information and answer questions concerning the technique of the artist and the quality of the construction materials, the following analytical protocol was adopted:

1. study of the synthesis and the stages of creation, in order to produce a profile of each painting with: a) macroscopic and stereoscopic examination, and b) the use of multispectral imaging.

2. Study of the canvas and the priming which was stretched on its reverse side. The aim is to investigate the provenance of the canvas and the priming composition with: a) macroscopic and stereoscopic examination of canvas, b) scanning electron microscopy coupled to energy dispersive X-ray spectrometer (SEM-EDX), c) application of lasers and in particular laser-induced breakdown spectroscopy LIBS for the characterisation of the inorganic elements of the priming, d) staining of cross-sections for the determination of the priming’s binding medium, e) infrared spectroscopy (FTIR-ATR) for the identification of the binding medium of the priming.

3. Study of the signature, in order to detect at which stage the painting was signed and at what degree it incorporates into the paint layer with the use of: a) macroscopic and stereoscopic examination, and b) multispectral imaging.

4. Identification of specific pigments, in order to study their composition and acquire a broader image of the construction techniques of the paintings with: a) scanning electron microscopy coupled to energy dispersive X-ray spectrometer (SEM-EDX), b) application of lasers and in particular LIBS, and c) infrared spectroscopy (FTIR-ATR).

5. Identification of the paint’s binding medium with: a) staining of cross-sections, and b) infrared spectroscopy (FTIR-ATR).

6. Collection, verification and cross-examination of the findings with reference samples, existing sources and publications.

4 Results

As it is understandable the full study and results cannot be shown in detail in this paper. Therefore only few exemplary but characteristic results are chosen to be presented whereas the conclusions refer to the full extent of data analysis.


The macroscopic study of the painting led to many observations with most prominent that the painting is very well preserved and there are no deterioration signs. The painting was examined in the spectral regions from 320-950nm by multispectral imaging system IRIS aiming to detect under-drawings, revisions and areas of later alterations. However, in the current painting no differentiations in the pigments were observed, apart from the pigment used for the signature which presents different absorption from the rest of the painting in wavelengths higher than 700nm.

Samples from the priming were examined under 200x magnification and revealed the presence of two layers. Above the layer of the fabric substrate, there is a homogenous in consistency layer, of uneven thickness fluctuating from 40μm up to 100μm and is whitish in colour. A second layer is brighter in colour with thickness of 30 to 35μm. Between the canvas support and the first layer of priming, a homogenous layer of brown colour is observed. LIBS analysis was performed on selected spots of the priming area in order to identify the pigments used. For the analysis the LIBS, LMNT-II system was employed and the following elements detected at priming’s area Zn, Ba, Pb, and Ti were attributed to compounds of Zn (ZnS or ZnO), barium sulphate (BaSO4), lead oxide (PbO) and titanium oxide (TiO2) respectively.

Fig. 2. The SEM-EDX spectrum in analysis of the upper layer of priming

The elemental analysis by SEM-EDX of the upper layer of the priming, figure 2, detected elements such as titanium, barium, lead, and sulfur in major quantities along with other elements of minor importance. The presence of those elements indicates the use of titanium white and lead white in combination with barium sulphate.

Furthermore, in order to get a complete idea of the detected elements distribution, mapping technique was applied to the whole sample.

The study of the particular cross-section showed that the priming consists of two layers. The upper layer is mainly of inorganic composition and consists of a mixture of lead white, titanium white, calcite and barium sulphate. On the contrary, the lower layer seems to contain a big amount of organic medium in combination with zinc white. The thickness of the layers indicates that the upper part was possibly used as a


coat for the main layer. Additionally, the homogeneity along with the size of the grains of both layers is indicative of industrially produced priming.

Fig. 3. Mapping of the sample. The first square shows the analysed area, while the rest show where each element was detected and at what concentration.

From the mineralogical point of view X-ray diffraction analysis at figure 4 confirmed findings of zincates (ZnO), hydrocerussite (Pb3(CO3)2(OH)2), baryte (BaSO4), calcite (CaCO3) and revealed titanium dioxide (TiO2) to be present in the crystal form of rutile at priming’s area.

Analysis by LIBS was performed on selected areas of the painting in order to identify the pigments used for the painting layers. However LIIBS detected the presence of calcium (Ca), titanium (Ti) and zinc (Zn), indicating the presence of chalk (CaCO3) or gypsum (CaSO4), titanium dioxide (TiO2) and zinc oxide or other structure of zinc (ZnO or ZnS). Such regular findings of white pigments and extenders signify a single paint manufacturer for most paints presented on the painting.


79-1342 (C) - Dolomite - CaMg(CO3)2 - I/Ic PDF 2.5 - 21-1276 (*) - Rutile, syn - TiO2 - I/Ic PDF 3.4 - 03-0596 (D) - beta-Calcite - CaCO3 - 05-0448 (D) - Barite - BaSO4 - I/Ic PDF 2.6 - 13-0131 (I) - Hydrocerussite, syn - Pb3(CO3)2(OH)2 - 36-1451 (*) - Zincite, syn - ZnO - Operations: Smooth 0.150 | Back.(in Sqrt) 1.000,1.000 | ImportAKROPOLIS SYLLOGIS D. DIAMANTIDI - File: KOUSIAKI_AKROPOLI_20081014.raw - Type: 2Th/Th locked - Start: 3.000 ° - End: 69.980 ° - Step: 0.020 ° - Step time: 2. s - Temp.: 25 °C (Room) - Time Started: 0 s - 2-T

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ount

s)

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2-Theta - Scale

37 40 50 60

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t (C

ount

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RUTILE RUTILERUTILE RUTILE

RUTILERUTILE RUT

RUTILE

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Fig. 4. The XRD spectra revealed Ti rutile presence

Fig. 5. Detail of painting taken under raking light

5 Discussion of Results

The aforementioned results showed that the majority of the analyzed paints include titanium white (TiO2) in combination with specific extenders. Admixtures of white pigments and extenders, eg. titanium white with plaster, titanium white with barytes, titanium white with zinc white or titanium white with lithopone was already common practice from first quarter of the twentieth century for the industry of paints in order to achieve modification of the properties of paints. With the turn of the century, zinc white had replaced the poisonous lead white but the fragile paint layer that zinc white produces and the better hiding power of titanium white or lead white, led to the replacement of zinc with titanium white, specifically after 1945 [13, 14].


Furthermore the crystallographic analysis confirmed the crystal structure of the components. Zinc white is most probably associated with the first layer rather than the second. However the synthesis of titanium is an important clue in confirming its date of production since different crystal forms or various combinations with other white pigments where employed in different seasons [15]. There are two main crystal forms of titanium dioxide; anatase and rutile. With regard to the crystal form of titanium anatase as a pigment this is presented around the 1920s, while the rutile appears only after 1940s when it began to be systematically used for oil paints [16]. Therefore the painting could not have been created before 1940, as it was initially suggested.

6 Conclusions

The aim of ultimate documentation was achieved and successful data and results were obtained. The presented study is a successful application of integrated documentation through a well-structured evidence of the painting in dispute and its construction technique and materials. Post processed steps include archiving, securing coding of data if needed. The paper’s ambition is to prove the important contribution of science as a tool in cultural heritage research as well as in securing each and single one cultural treasure.

The method, procedure and system of UD are also available for private and public applications upon demand with prices depended on the artwork condition, location, place, problems. Thus always a prior study for a custom-made offer is required. Training on the system and method is also possible upon demand. Hence the technology can be considered as a pre-industrial stage of development available to public and market. Acknowledgements. The project is a continuation of the study undertaken for the EC project MULTIENCODE (SSP-006427) coordinated by Vivi Tornari (IESL/FORTH). Special thanks for the support to the present study are acknowledged to E. Varella (Aristotle University of Thessaloniki), V. Papadakis and A. Giakoumaki (IESL-FORTH), G. Economou and D. Tarenidis (IGME), M. Mariglis and Th. Dimogerontakis (ELKEME).

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13. Brindley, B.H.: Australian Home Decorator and Painter. A Colour gravure Publication, Melbourne (circa, 1952)

14. Koussiaki, F.: The Influence of non-traditional Art Materials on the Paintings of Pablo Picasso. In: Postprints, AIC Paintings Specialty Group, 30th Annual Meeting. The American Institute for Conservation of Historic and Artistic Works, Miami, Florida, pp. 39–48 (2002)

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