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
consci@artgnomon.com
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.
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
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.
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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
3
TAE+CF+A
1. Whole information
2. determination of data
3. features extraction
4. total data
5. useful data
6. interconnection of data
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
Science in Aid of Expert Opinion: A Tell-Tale on Disputed Artworks
877
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
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F. Koussiaki et al.
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.
2.
3.
4.
5.
6.
4
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.
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 laserinduced 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.
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.
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).
Identification of the paint’s binding medium with: a) staining of crosssections, and b) infrared spectroscopy (FTIR-ATR).
Collection, verification and cross-examination of the findings with reference
samples, existing sources and publications.
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.
Science in Aid of Expert Opinion: A Tell-Tale on Disputed Artworks
879
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
880
F. Koussiaki et al.
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.
Science in Aid of Expert Opinion: A Tell-Tale on Disputed Artworks
881
600
Sqrt (Counts)
500
400
RUTILE
300
R
200
100
10
0
3
10
20
30
600
Sqrt (Counts)
500
400
300
200
RUTILE
100
RUTILE
RUTILE
RUTILE
RUTILE
RUTILE
RUT
10
0
37
40
50
60
2-Theta - Scale
AKROPOLIS 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
Operations: Smooth 0.150 | Back.(in Sqrt) 1.000,1.000 | Import
36-1451 (*) - Zincite, syn - ZnO 13-0131 (I) - Hydrocerussite, syn - Pb3(CO3)2(OH)2 05-0448 (D) - Barite - BaSO4 - I/Ic PDF 2.6 03-0596 (D) - beta-Calcite - CaCO3 21-1276 (*) - Rutile, syn - TiO2 - I/Ic PDF 3.4 79-1342 (C) - Dolomite - CaMg(CO3)2 - I/Ic PDF 2.5 -
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].
882
F. Koussiaki et al.
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 (IESLFORTH), G. Economou and D. Tarenidis (IGME), M. Mariglis and Th.
Dimogerontakis (ELKEME).
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