Information: conservation@benaki.gr
The relatively large demand for art works and / or archaeological artefacts means that, inevitably, it cannot be covered with artefacts whose provenance is legal; so that increasingly this demand is turning to the illicit trade in antiquities and the creation of forgeries and fakes. This problem is further aggravated by the fact that the question of authenticity is mainly viewed from the point of view of Art Historians and not always in combination with physical and chemical analytical methods, even though these too can be misled by faked “aging” of the object in question. UNESCO has proposed the production and marketing of high quality, “museum” quality copies by reviving ancient production methods and using authentic raw materials, not only in order to promote cultural heritage, but also to satisfy demand and blunt economic pressures, which encourage illicit trade in antiquities and the creation of forgeries and fakes. This proposal has already been accepted by some countries. Unfortunately, from a technical standpoint, when a copy is very faithful, the temptation to place it back on the market as an authentic piece increases. To this end, suitable methods of tagging these objects are required, in order to avoid finding these copies on the market as authentic pieces. The project, which was carried out, aimed to develop:
1. Integrated Elemental Tagging Technology (IETT) to safeguard the identity of the copy.
2. IETT for conservation materials for authentic archaeological artefacts, in order to safeguard their identity in a manner that would help discourage replacement or theft of paintings or metal objects.
3. IETT for contemporary conservation materials for icons and paintings. The creation of a data base that would include pigments and conservation materials for works of selected Greek Icon Painters and Painters from the 16th to the 20th century.
4. Integrated System of Ionic Non-Destructive Techniques for Authentication, which would, on the one hand easily identify IETTs but would also provide a versatile tool to investigate the authenticity of any other untagged work of art or archaeological artefact. Furthermore, in order for private agencies to be able to undertake quality control of the IETT application, the development of a low-cost, simple-to-use, portable X-Ray fluorescence spectrometer (XRF) was proposed, which would provide software suitable for use by non-expert staff.
In summarising the results of the IETT programme, the significant achievements that came up will be noted as these correspond to the initial goals.
The results in the selection of chemical tags, which could be incorporated either into a dye or into the corpus of technological ceramic copies and conservation materials were summarised in two ranked multi-parameter tables, which included all the candidate chemical elements. The methodology was developed to incorporate chemical tags in ceramic copies decorated with clay dyes and undecorated, but also in conservation materials, such as the acrylic resin Paraloid B72, in acrylic paints for paintings and in microcrystallic waxes (Renaissance wax) for metal artefacts. In the case of decorated ceramics, the tag is applied before the ceramic enters the kiln, while in undecorated ceramics, tagging takes place by spraying immediately after the objects are removed from the kiln and while they are still hot.
In order to trace the integrated elemental tagging (IET) in ceramic copies and conservation materials, a methodology was developed to measure and quantify this on the basis of X-Ray Fluorescence, XRF. To this end, but also in order to carry out quality controls on the production process for IET, an original portable XRF spectrometer was developed, which was designed, manufactured and evaluated within the framework of the programme and was finally installed on site at the newly-established Non-destructive analysis laboratory at the Benaki Museum.
In order to deal in a more integrated manner with issues of authenticity for artworks and archaeological artefacts, but also in order to carry out a more in-depth quality control of the IET, the Demokritos National Centre for Scientific Research developed an integrated system of non-destructive techniques, which includes an experimental external ion beam station with the support and collaboration of three different ion beam techniques (PIXE: particle-induced X-ray emission; RBS: Rutherford back-scattering spectrometry; and PIGE: particle-induced gamma-ray emission), as well as in a scattering chamber for the application of the innovative PIXRF (Proton-induced X-ray fluorescence) technique. The aforementioned experimental arrays were designed, built and put in place with all the necessary support equipment and electronic arrays as part of the IETT programme. Systematic research led to the development of appropriate analysis protocols, which include optimised experimental measurement conditions for each type of artefact, in order to achieve simultaneous and combinatorial analysis with the different spectrometers; a methodology for calibrating each technique; and software packages, which support the spectrum analysis and the extraction of processing of analytical data. Special emphasis was placed on developing a new methodology for non-destructive analysis of the distribution of the concentration of an element in respect to depth. Within this framework theoretical grounds were developed for the quantification of a novel innovative technique, confocal micro-PIXE, so that with the help of appropriate analysis software and data processing, the elemental distribution of concentrations could be calculated at each depth. This methodology was applied to the non-destructive elemental analysis to the depth of glazed pottery and artificial patina developed on the surface of metal alloys. Finally these non-destructive techniques were utilised to investigate the potential for defining the distribution of hydrogen at each depth, in glazed ancient pottery and in technologically faithful copies through appropriate nuclear resonance reaction.
The technology of incorporated elemental tagging was implemented and suitably evaluated in real conditions for the production of technologically faithful ceramic copies, as well as on specific conservation materials, such as microcrystallic wax and acrylic resin in the collection of metal artefacts of Byzantine and Islamic Art and in a 19th century icon of minor historical significance respectively. It is worth noting that tagged ceramic copies are on sale at the Benaki Museum Shop and at the Cycladic Art Museum Shop, while they have also gone on display with special collections (the Aigaleo metro station; the exhibition: “The excavation at the new Acropolis Museum”, which took place in Beijing as part of the 2008 Olympic Games; the exhibition “Athenian Democracy” in March 2007 at the Foundation of the Hellenic World).
The analytical specifications of the portable XRF spectrometer, as regards its potential for non-destructive diagnosis and characterisation of materials, were evaluated on the one hand by the analysis of specific portable icons, including the “Adoration of the Magi” and “Luke the Evangelist” by Domenicos Theotokopoulos; “Saint George riding a horse” by renowned Cretan painter Angelos (second half of the 15th century); as well an icon by Georgios Klotzas on the same topic; on the other hand by the characterisation of the palette of pigments from 10 representative oil paintings from early works by Nikos Hadjikyriakos-Glika, whose oeuvre is plagued by forgeries. Analysis of the portable icons allowed identification of many of the pigments utilised; the preparation materials; and also recognised possible later conservation interventions. The pigments determined by the analysis results from the oil paintings by Nikos Hadjikyriakos-Ghika were included in a data base at the Benaki Museum. Select works (an oil painting by Nikos Hadjikyriakos-Ghika, a portable icon from the Valadoros Collection, 18th century) were also analysed using these non-destructive techniques and the results were evaluated by comparison with the corresponding results provided by XRF analysis. Comparative examination of specific works using other non-destructive analytical techniques (using the ultraviolet, visible and infra-red spectrum of electromagnetic radiation, with near IR spectrometry etc), and the creation of a data base of original pigments utilised in 19th and 20th century Europe and, specifically, in Greece, with the application of these particular non-destructive techniques and XRF was of great help in improving the reliability of the analytical non-destructive atomic and ion beam techniques, which were developed in the framework of the IETT programme.
In conclusion the results of the IETT programme are evaluated as being particularly momentous, as significant innovation was developed as far as infrastructure was concerned (Integrated System of Ion Beam Non-Destructive Techniques, ISIB-NDT; a portable XRF; a Non-Destructive Technique Laboratory at the Benaki Museum), the analytical methodology of IETs for ceramic copies and conservation materials is judged to be a worldwide innovation. IET is a very promising methodology to safeguard the identity of technologically genuine copies and the authenticity of authentic works and artefacts of our cultural heritage. Programme: Joint Ventures for Research and Technology Development in sectors of National Priority.
Associated Agencies: Ministry of Development – General Secretariat of Research and Technology European Fund of Regional Development (funding); Demokritos National Centre for Scientific Research / Institute of Nuclear Physics (Contractor); THETIS Authentics Ltd.; The Benaki Museum – Conservation Department: Stergios Stassinopoulos, Despina Kotzamani, Alexandra Kalliga, Eleni Vranopoulou, Vassiliki Apostolopoulou, Harilaos Grammatikos, Ioanna Providi.