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

Abstract

The chemical and physical alterations of cadmium yellow (CdS) paints in Henri Matisse's The Joy of Life (1905Life ( -1906, The Barnes Foundation) have been recognized since 2006, when a survey by portable X-ray fluorescence identified this pigment in all altered regions of the monumental painting. This alteration is visible as fading, discoloration, chalking, flaking, and spalling of several regions of light to medium yellow paint. Since that time, synchrotron radiation-based techniques including elemental and spectroscopic imaging, as well as X-ray scattering have been employed to locate and identify the alteration products observed in this and related works by Henri Matisse. This information is necessary to formulate one or multiple mechanisms for degradation of Matisse's paints from this period, and thus ensure proper environmental conditions for the storage and the display of his works. This paper focuses on 2D full-field X-ray Near Edge Structure imaging, 2D micro-X-ray Diffraction, X-ray Fluorescence, and Fourier Transform Infra-red imaging of the altered paint layers to address one of the long-standing questions about cadmium yellow alteration-the roles of cadmium carbonates and cadmium sulphates found in the altered paint layers. These compounds have often been assumed to be photo-oxidation products, but could also be residual starting reagents from an indirect wet process synthesis of CdS. The data presented here allow identifying and mapping the location of cadmium carbonates, cadmium chlorides, cadmium oxalates, cadmium sulphates, and cadmium sulphides in thin sections of altered cadmium yellow paints from The Joy of Life and Matisse's Flower Piece (1906, The Barnes Foundation). Distribution of various cadmium compounds confirms that cadmium carbonates and sulphates are photo-degradation products in The Joy of Life, whereas in Flower Piece, cadmium carbonates appear to have been a [(partially) unreacted] starting reagent for the yellow paint, a role previously suggested in other altered yellow paints.

Degradation of Cd-yellow paints: Ab initio study of native defects in {10.0} surface CdS

“…Thus, their identification alone does not conclusively make them sub-products of photo-oxidation processes because traces of them are also found within layers away from the surface. This type of degradation was also found on the surface of faded cadmium yellow paints in the following works: Still Life with Cabbage [2] by James Ensor, The Joy of Life [3,4] and Flower Piece [5] by Henri Matisse.…”

“…As suggested from these studies [2,3,4,5], CdCO 3 and (CdSO 4 ·nH 2 O) are degradation products of photo-degradation processes occurring in The Joy of Life, Flower Piece and The Scream by Edvard Munch. Furthermore, in these two last paintings the cadmium carbonate may be related to a partially unreacted starting reagent.…”

“…Pouyet et al, using analytical methods [5] with a high sensitivity and ability to map the distribution of this compound, proposed an explanation of the synthesis and degradation pathways of cadmium pigment in several paintings. As suggested from these studies [2,3,4,5], CdCO 3 and (CdSO 4 ·nH 2 O) are degradation products of photo-degradation processes occurring in The Joy of Life, Flower Piece and The Scream by Edvard Munch.…”

“…Furthermore, in these two last paintings the cadmium carbonate may be related to a partially unreacted starting reagent. To address the question of the origin of CdCO 3 , measurements [5] on an altered paint cross-section coming from the Flower Piece painting, ultraviolet illuminated, revealed in the shallower portion of the sample, an orange fluorescence suggestive of CdS particles dispersed in a zinc white. The origin of these fluorescent emissions has not been conclusively established and further analyses with better resolution are necessary in non-degraded yellow areas of the painting.…”

Change is permanent: thoughts on the fading of cochineal-based watercolor pigments

“…The presence of pararealgar in paintings has been shown to be due to transformation of realgar on exposure to visible light [2], certain forms of lead chromate (apparently those prepared a specific way) are not stable in light and react with the binder, changing color and decreasing the strength of the paint film [3]. The complexity of factors involved in the color changes of inorganic pigments such as red lead [4,5], cadmium yellow [6], and vermilion [7][8][9]-long observed-have been investigated. These pigments can be synthesized using different methods or have variations in their formulation that give products with different hues and significantly different reactivity.…”