THE EXAMINATION OF DRAWINGS BY GEORGES SEURAT USING FOURIER TRANSFORM INFRARED MICRO-SPECTROSCOPY (MICRO-FTIR)

Drawings by Georges Seurat in the collection of TheMuseum of Modern Art were examined for a recent exhibition.Fourier transform infrared micro-spectroscopy (micro-FTIR) has found a shellac fixative on all of the drawingsexamined. It is apparent that Seurat applied this resinbecause it appears in areas corresponding to the early passagesin the drawing composition. Evidence suggests thatthe fixative was mainly applied to increase the tooth forlater applications of conte crayon and to prevent thesmudging of lower layers. Typically, the layers of shellacare extremely thin and based on visual appearance and autofluorescencesuggestive of decolorized shellac. The useof an ultraviolet (UV) illumination attachment on the FTIRmicroscope made positioning of the aperture a very efficientprocess that helps locate the shellac. While anecdotalinformation has suggested conte crayon used by Seuratcontains wax, FTIR, UV fluorescence and PyGC-MS did notdetect any. These scientific findings accurately reflectinformation contained in Nicholas-Jacques Conte’s originalpatent from 1795.