Integrating imaging FTIR and secondary ion mass spectrometry for the analysis of embedded paint cross-sections

Novel chemical imaging techniques provide new insight in the organic chemistry of embedded paint cross-sections. FTIR imaging microscopy delivers a two-dimensional image of the functional group distribution, revealing chemical aspects of the binding medium in each individual paint layer. Secondary ion mass spectrometric imaging of the paint cross-section surface provides the molecular identity of chemical compounds in the layer. The integrated application of FTIR and SIMS imaging reveals the presence, spatial distribution and molecular identity of various organic and inorganic compounds. The strength of these chemical imaging techniques is demonstrated in the characterization of the organic constituents found in microscopic inclusions in the surface of Rembrandt's Anatomy Lesson of Dr. Nicolaes Tulp. These techniques provide experimental evidence on the combined presence, distribution and identity of various lead soaps and lead hydroxychloride in these inclusions.