Pigment identification studiesin situ of Javanese, Thai, Korean, Chinese and Uighur manuscripts by Raman microscopy

Abstract

The full palettes of one Javanese and four Thai manuscripts, from the collection of the British Library Oriental Department, were studied by Raman microscopy in order to investigate the degradation shown by some of the pigments and to characterize the palette. Vermilion, red lead, red ochre, litharge, massicot, indigo, ultramarine blue, chalk, white lead, gypsum, anhydrite (anhydrous form of gypsum), baryte, orpiment, chrome yellow, chrome orange and a carbon-based pigment (such as lampblack) were detected on the manuscripts. Darkening of a lead pigment due to the formation of the black compound, lead(II) sulphide, was discovered on one of the manuscripts, and the friable nature of the pigments in other manuscripts is probably due to the humidity of the region of origin. Unusual mixtures of white pigments (e.g. white lead and chalk) were detected in the three nineteenth century manuscripts, and modern synthetic pigments were found on the most recent manuscript. Ultramarine blue was used on the late nineteenth century manuscripts, whereas indigo was used on the earlier ones. Indigo was very difficult to identify on manuscripts using early Raman microscopes, but recent improvements in the instrumentation used have enabled it to be detected on such artefacts for the first time here. It was identified subsequently to be the blue dye applied to three other Oriental manuscripts, one Korean, one Chinese and one Uighur. Copyright © 1999 John Wiley & Sons, Ltd.