SR-FTIR imaging of the altered cadmium sulfide yellow paints in Henri Matisse's Le Bonheur de vivre (1905–6) – examination of visually distinct degradation regions

Abstract

SR-FTIR imaging has been used to map the mid-IR active photo-degradation phases in two thin sections of cadmium yellow paint removed from Henri Matisse's Le Bonheur de vivre (1905-1906, The Barnes Foundation). These samples represent both the darkened cadmium yellow foliage in the upper left of the work and the lightened cadmium yellow field beneath the central reclining figures. The altered cadmium yellow paints from both regions were found to contain cadmium carbonate (CdCO3), cadmium sulphate (CdSO4), and cadmium oxalate (CdC2O4). Each of these phases was imaged to determine their positions as a function of depth, with the aim of better understanding the role of each phase in the degradation mechanism. This speciation mapping is critical because cadmium oxalate was used in this period as an additive in cadmium yellow light. In addition, cadmium carbonate and cadmium sulphate were synthesis starting materials for cadmium yellow, and so their distribution throughout the paint layer can provide an indication of their roles. It was established that cadmium oxalate is localized at the surface of the paint layer, cadmium carbonate is found deeper in the layer but still enriched at the surface, and cadmium sulphate is distributed throughout the layer. This distribution, along with the chloride content of the paint suggesting a cadmium chloride starting material, is consistent with an alteration mechanism in which the cadmium sulphide is oxidized to sulphate and this is then converted to carbonate and oxalate. The relative solubilities of the three photo-degradation products are also relevant to their locations in the paint film.

2D X-ray and FTIR micro-analysis of the degradation of cadmium yellow pigment in paintings of Henri Matisse

“…The section was then sandwiched between two ultralene foils (4 lm thick, from Spex Sample Prep) to provide mechanical stability during data acquisition. For lFTIR analysis, micro-compression was favoured because it prevents spectral contamination from the embedding material [12,13]. Considering that lXRF results are not affected by any of these forms of sample preparation (compressed sample between diamond windows, cross section, and thin section from embedded fragment), the resulting elemental maps allow the combination of results from X-ray and infrared spectroscopies together with the visible observations.…”

“…1a), in particular for preservation purposes. Studies were performed at different synchrotron facilities: at ID21 (ESRF), at BL4-3 (SSRL) [11], and at the IRENI (Synchrotron Radiation Center, SRC) [12,13]. By combining microFourier transform infrared (lFTIR) spectroscopy with micro-X-ray fluorescence (lXRF) and micro-X-ray near edge structure (lXANES) spectroscopy (at the Cd L III -edge and at the S K-edge in scanning mode), spectra were collected over dozens of points.…”

The Noninvasive Analysis of Painted Surfaces: Scientific Impact and Conservation Practice

“…This inhomogeneity of fluorescence reflects variability in the alteration products formed on the painting's surface and of the electronic structure of the remaining CdS. Alteration products identified thus far on Le Bonheur de vivre include cadmium sulfate, cadmium carbonate, and cadmium oxalate (Mass et al, 2013a(Mass et al, , 2013b. Another cadmium-containing species identified in the cadmium yellow paint in Le Bonheur de vivre, cadmium chloride, is thought to be present as a residual starting reagent (Mass et al, 2013a).…”

“…Potential CdS photodegradation products identified in the paintings included cadmium carbonate (CdCO 3 ), cadmium oxide hydroxide, cadmium carbonate oxide, and cadmium sulfate (CdSO 4 ). It is important to note that CdCO 3 and CdSO 4 are both reagents for the wet process syntheses of CdS, so their identification alone does not constitute conclusive proof of photooxidation (Mass et al, 2013b;Plahter and Topalova-Casadiego, 2011). However, the identification of these phases at the paint's surface as discolored degradation crusts can suggest that they were produced by a photooxidation mechanism.…”

“…A great deal of elemental, molecular, and microscopic characterization of these altered regions has been carried out by our group, and the fading has been attributed to photooxidation (Mass et al, 2013a(Mass et al, , 2013b. In particular, the off-white alteration crusts are composed predominately of the white cadmium compounds cadmium carbonate (CdCO 3 ) and cadmium sulfate (CdSO 4 ·nH 2 O; Mass et al, 2013a).…”