Study of Gustave Moreau's black drawings: identification of the graphic materials by Raman microspectrometry and PIXE

The identification of graphic materials with the naked eye is not always straightforward. A new collaboration with the Gustave Moreau museum in Paris offered the opportunity to test the combination of two analytical techniques in order to improve the knowledge of the materials used by this artist. The French painter Gustave Moreau (1826–98) made many monochromatic drawings on paper with black materials containing carbon such as black chalk, graphite or inks, and sometimes both materials on the same sheet. The nature of the support and that of the materials used prohibits any sampling and visual examination alone is not sufficient to identify all the materials. In order to provide a reference for the identification of the graphic technique, a first series of six drawings stored in the Gustave Moreau museum was brought to the Centre for Research and Restoration of the Museums of France for an extensive investigation. Examinations under a binocular microscope, using IR radiation, combined with PIXE analyses with the external beamline of the ion beam analysis facility and by Raman microspectrometry resulted in the identification of graphite pencil, pure graphite, reconstituted black chalk and two inks, one of which was probably a 19th century ink and made with logwood. The analysis of this first set of drawings enabled us to determine the graphic techniques of 10 other drawings by simple visual observation. Copyright © 2004 John Wiley & Sons, Ltd.