Mobile UV-VIS Absorption Spectrometry Investigations in the “Alexander-Sarcophagus” in Istanbul

Abstract

For several years, UV-VIS-spectrometry has been employed to identify colorants used in the polychromy of diverse art objects such as paintings, textiles and ancient sculptures. UV-VIS-spectrometry is a non-destructive method used to identify colorants (pigments and dyestuffs). The surface to be examined is briefly illuminated by white light. Part of the white light is absorbed and part is reflected. The reflected light is detected and split by a spectrometer. Achromatic materials can also be identified if the spectral range is adjusted to the visible light in the near UV and the near infrared region. The spectra can be compared with those in specially created data libraries. The combination of high efficient optical equipment such as light source, fibre optics and diode-array detector together with the mathematical preparation of the spectra enables us to identify successfully nearly 90% of the colorants without taking samples. The various technical options for this analytical method and the results obtained by examining the Alexander-sarcophagus owned by the Archaeological Museum of Istanbul will be illustrated. It was possible to identify more than 24 colorants.