Bronze Age painted plaster in Mycenaean Greece: a pilot study on the testing and application of micro-Raman spectroscopy

Since the first discoveries of Minoan and Mycenaean painted plaster around the end of the 19th and early 20th centuries, iconographic and, to a lesser extent, technological studies have gone hand in hand in order to understand how these prehistoric societies were able to produce some of the earliest and most significant works of art in Bronze Age Europe and the eastern Mediterranean. These paintings claim to be among the first to be executed in the buon fresco technique. Past technological studies employed wet chemical methods, x-ray diffraction (XRD), optical emission spectroscopy and a range of microscopic techniques based on cross-sections of samples in order to investigate these fragmentary paintings. Most of these methods required destructive sampling and this is now, rightly so, very much restricted. Consequently, other non-micro-destructive approaches are being tested at present. Micro-Raman spectroscopy (MRS) has proven more than once its potential for non-destructive analysis of works of art and in archaeology in the recent past. Its application to this early fragmentary material is presented here for the first time. Interesting results were the identification of both organic (indigo) and non-crystalline materials (limonite), which complements the knowledge obtained from traditionally used techniques. Although not without problems (high fluorescence prevented identification of Egyptian Blue), non-destructive MRS yielded results comparable to XRD and provided the first identification of indigo blue on this medium, and can hence be considered very useful in future sample-reducing strategies considering these scarce materials. Copyright (C) 2004 John Wiley Sons, Ltd.