Pigment identification of an illuminated mediaeval manuscript De Civitate Dei by means of a portable Raman equipment

Abstract

Direct identification of pigments in mediaeval illuminated manuscripts was one of the first applications of Raman spectroscopy in art and archaeology. In previous in situ analysis of handwritings, the equipment was typically provided with a single excitation source. In this work, a portable Raman spectrometer (EZRAMAN-I-DUAL Raman system) is introduced to characterise the pigments used in an important illuminated mediaeval manuscript, De Civitate Dei (Library in Bruges, Ms.106). Characteristics important for these in situ measurements were discussed. We introduce a set-up that allows stable positioning of the equipment and point out the advantage of the availability of two lasers, which are part of the instrument. Good performance of the introduced Raman spectrometer, to allow pigment identification in a short time, is proved. Finally, pigments such as lead white (2PbCO3 · Pb(OH)2), lead-tin yellow type I (Pb2SnO4), malachite (Cu2CO3(OH)2), mosaic gold (SnS2), vermillion (HgS), carbon black (C), red lead (Pb3O4) and azurite (Cu3(CO3)2(OH)2) could be identified. These pigments were often used in mediaeval artworks and contribute to the enrichment of information of the materials used by the illuminator.