Analytische Chemie
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Since the advent of industrial computed tomography (CT), this new analysis method has been used also for the investigation of objects of cultural heritage and art. CT provides the possibility to determine the inner and outer surfaces and to investigate the material structure without causing damage to the valuable objects.
In this talk I will present examples of measurements performed at BAM, which demonstrate what CT can do for objects of diverse materials and for different objectives.
Light damage to selected organic materials in display cases: A study of different light sources
(2016)
The protection of works of art and cultural assets against light-induced aging is vital when planning exhibitions. Newly developed lighting systems render the selection of suitable light sources more difficult, not least in the context of energy–economical systems. This study accordingly examines different lighting systems (fluorescent tubes, halogen lamps, low-voltage metal halide lamps, and LED lamps) in terms of the damage potential they hold for the materials concerned. The changes in color were evaluated using the CIEDE2000 color-difference formula. This study focuses on selected organic materials and shows that changes in color already occur after only a brief exposure time. The color changes induced by the fluorescent tubes were consistently more intense than those induced by the other light sources. The results obtained with the remaining lamps show that the color changes depend more on the material under investigation than on the source used. The changes determined after a relatively short exposure period (five months) vividly demonstrate that exposing sensitive materials to light for longer terms (as is the case during a permanent exhibition) is most definitely a non-viable option.
The International Qumran project conducted at the BAM Federal Institute for Materials Research and Testing in 2007–10 aimed at establishing an optimal methodology for an accurate characterization of the Dead Sea Scrolls to address such questions as archaeological provenance, origin, and attribution of fragments to a specific sheet (Rabin 2013). Using equipment of various degrees of complexity we have shown that part of the historic information stored in the material can be revealed by proper characterization of the material. The on-site investigation of the Dead Sea Scrolls fragments from The Schøyen Collection in October 2012 offered the first chance to test this methodology in a field study. For the first time, we used mobile and non-invasive technology exclusively, since we could not transport all of our laboratory equipment to Norway for this project. Moreover, besides the technical limitations dictated by the available equipment, we had to cope with limited time: it was impossible to perform the number of scans required for optimal characterization of over 30 fragments within the fourteen days available. Nevertheless this study presents an important step in the material analysis of the Dead Sea Scrolls, since the devices we used are easily transportable, well known, and easily accessible throughout the world.
The international Qumran project coordinated at the BAM, Berlin, resulted in an integrated methodology for determining the original and acquired properties of the skin-based writing surfaces of the Dead Sea Scrolls. This methodology offers a powerful tool for addressing such questions as the provenance, sorting and comparison of manuscripts. In addition, we have developed specific protocols for on-site studies, which were successfully applied to the fragments from the Schøyen collection in Norway. Our studies show that the Dead Sea Scrolls writing surfaces can be divided roughly into three groups: leather, parchments of a light tint, and those of various shades of brown. The latter ones are invariably tanned, whereas the middle group is characterized by the presence of various inorganic salts. Some of the pale parchments, among them the Temple Scroll (11Q19), are remarkably similar to medieval European parchment. Therefore we have formulated the working theory that in the Judaea of the Hellenistic period two different parchment-making traditions existed side by side: an ‘eastern’ one (represented by the tanned parchments of Qumran, closely resembling Aramaic documents from the fifth century BC, and a ‘western’ one (represented by the untanned/lightly tanned ones similar to early Christian Greek parchments).
This division has found support during our first pilot study of the Geniza fragments, in which Babylonian and Palestinian traditions seem to follow the “eastern” and “western” technologies, respectively.
The evolution and socio-geographic distribution of writing inks in late Antiquity and the early Middle Ages build the second focus of the BAM group. We use X-ray fluorescence analysis (XRF) to determine the chemical composition of the inks and NIR-reflectography for their typology. Here the early appearance of the metal containing inks clearly belongs to the western tradition as opposed to the continuous use of soot inks in the East.
The lecture will discuss the sensitive issue of authentication of the objects of cultural heritage of immense cultural and monetary value if certified to be genuine. It will be made clear that material analysis alone, especially its non-destructive variety conducted by specialists in a single technique, can not prove that the object is genuine. The best material analysis can do, after all appropriate tests have been conducted, is to announce that nothing has been found that contradicts the assumption of genuineness. Moreover, the results of the natural analysis can never be used as the only justification of the authentication in the cases of composite objects such as manuscripts or epigraphs. A certification always requires the expertise of the specialist in the field (be it a historian, paleographer, epigrapher, etc.), whose judgment can be at the most supported by appropriate material analysis.
The most effective approach for testing suspicious artifacts has been established by the forensic science. Here, not the authentication, but the determination of the forgery stands in the focus of the work. Investigation protocols developed within 150 years and constantly improved include a clear statement of the analysis purpose and the definition of plausibility criteria for the possible outcome. The younger sister of the forensics, archaeometry has to overcome additional obstacles such as the heterogeneity of historic material coupled with the scarcity of suitable reference material. Over the last two decades the popularity of archaeometric studies has increased enormously, with the industry-driven development of so-called non-destructive technologies (NDT) that do not require sampling. Further technological developments led to the appearance of NDT methods with extremely small interaction windows (µm range). Each of these methods has limitations that have to be carefully considered when planning the tests of a heterogeneous and often partially degraded historical material. This approach is inherently multi-instrumental, therefore archaeometric and forensic departments unite a number of specialists who work together defining the tasks and the methods involved for their successful completion.
The experimental knowledge about the inks of antiquity and late antiquity rarely goes beyond their visual description. In rare cases, inks typology has been determined by means of microscopy and reflectography, i.e. using their physical and optical properties, respectively. Soot, plant, and iron gall inks form different typological classes of historical black writing materials. Soot ink is a fine dispersion of carbon pigments in a water-soluble binding agent; plant-based ink consists of tannin solution; iron gall-ink presents a boundary case between soot and plant ink— a water soluble preliminary stage (similar to inks from the second group) oxidizes and evolves into a black, insoluble material (similar to the carbon pigments of the first group) when the writing is exposed to air. Each ink class has distinct properties that would readily permit their easy differentiation, if only these historical inks always belonged to just one of the classes above. In reality, inks may contain additives that obscure a clear picture.
All the black inks of the DSS have been hitherto identified as soot inks. Yet some manuscripts, with 1QapGen ar among them, display ink corrosion that is incompatible with the pure soot ink. This type of corrosion commonly observed in medieval manuscripts written with iron gall inks, results from the catalytic action of metallic component in the ink. Early analysis of this ink conducted by Nir El and Broshi in 1996 found copper in the corrosive inks and attributed its presence to the use of bronze inkwells. Re-investigation of the 1QapGen ar ink suggests, however, that the ink composition, soot + copper, agrees well with the ink recipe recorded in the 1st century CE by Dioscorides. Similar inks have been already attested on contemporary Egyptian papyri. The first part of the paper is dedicated to the new results on the inks and corrosion pattern of the 1QapGen ar.
In the second part of the presentation I will focus on the luxury scrolls, a distinct codicological type introduced by E. Tov. Our studies show that the preparation of the writing materials cannot supplement the list of codicological criteria offered by Tov. Therefore, one can divorce the writing material production from its inscription in contrast with the medieval scriptoria practices that included parchment production and copying of the manuscripts.
Material study of inks
(2016)
Our experimental knowledge about the inks of antiquity and late antiquity rarely goes beyond their visual description. In rare cases, inks typology has been determined by means of microscopy and reflectography, i.e. using their physical and optical properties, respectively. Soot, plant, and iron gall inks form different typological classes of historical black writing materials. Soot ink is a fine dispersion of carbon pigments in a water-soluble binding agent; plant-based ink consists of tannin solution; iron gall-ink presents a boundary case between soot and plant ink— a water soluble preliminary stage (similar to inks from the second group) oxidizes and evolves into a black, insoluble material (similar to the carbon pigments of the first group) when the writing is exposed to air. Each ink class has distinct properties that would readily permit their easy differentiation, if only these historical inks always belonged to just one of the classes above. In reality, inks may contain additives that obscure a clear picture.
Even crude observations suggest that the inks of antiquity differed greatly in their composition. We believe, that reconstructing the ink recipes with the help of advanced non-destructive analytical techniques could serve as a powerful accessory in the studies of ancient papyri.
The proposed paper will present a short survey of the methods of material analysis and the challenges offered by ancient inks. (Two) examples of ink studies from the collections of the Israel Museum in Jerusalem and Egyptian Museum in Berlin will conclude the paper.
We have obtained a minute amount of dry ink scratched from the bronze inkwell MS 1655/2. The powder was stored between two glass slides to minimize contamination. For micro analysis by FTIR a sample of the ink powder was transferred into a diamond cell while for confocal Raman spectroscopy a micro sample was placed onto sticky tape. The same portion of the sample was also investigated by scanning electron microscopy, where the elements distribution was determined by EDX.
The aim of our work was to check whether the assumption that the jar was discovered in Qumran can be substantiated. In order to establish the archaeological provenance of the jar we conducted a series of analytical tests on samples of material collected from the jar in April and June 2009. The samples were either found loose within the jar, these being probably constituted by remnants of its original contents, or were clay detached from the inner and outer surface of the jar. In addition, a portion of sand deposit coating the inside of the jar handles was analysed.
This paper reports the outcome of an interdisciplinary team’s application of multispectral imaging techniques and material analysis to a music fragment from the first decades of the fifteenth century: Atri, Archivio Capitolare, Museo della Basilica Cattedrale, Biblioteca del Capitolo della Cattedrale, Frammento 17. This important parchment leaf has rarely been investigated since its discovery 45 years ago. Thanks to the applied techniques and methods (such as the evaluation of the data using the fingerprint model), it is now possible to discuss new evidence supporting conclusions regarding the fragment’s origin and afterlife.