AIC's 46th Annual Meeting

Pablo Picasso’s ‘Femme’ (c. 1908; Beyeler Foundation, Basel, CH) is an oil study related to ‘Les Demoiselles d’Avignon’. A collaborative, multi-analytical, technical examination of the painting was carried out to answer questions about the artist’s materials and technique during an important, but relatively understudied, period of his career. Of particular technical interest were two yellow passages: a visibly degraded cool lemon yellow and a seemingly intact warm yellow. To understand the nature of the degradation, and to better assess the risk of further alteration, the physical structure of both yellow paints were assessed by visible-light and UV microscopy, and the chemical composition characterized by ESEM-EDS, GC-MS, and μFTIR. Although cadmium sulfide (CdS) and barium sulfate were present in both yellows, the overall elemental composition, size, and distribution of particles suggested two different commercial paint preparations. Visible-light and UV microscopy of prepared cross sections revealed a distinctive boundary between the altered lemon yellow paint towards the surface and an unaltered zone below. Detectably higher concentrations of known CdS alteration products - cadmium carbonate, cadmium sulfate, and cadmium oxalate - were identified by μFTIR in the altered region of the degraded lemon yellow paint. These results suggest the paint underwent photo-oxidative degradation, resulting in both a surface discoloration and the breakdown of the physical structure of the paint film. In contrast, the warm yellow paint samples showed no such evidence of deterioration. In order to map and better characterise the optical emission of the paint and its degradation additional analysis was carried out using in situ fluorescence lifetime imaging (FLIM) of the whole painting, and time-resolved photoluminescence microscopy of microsamples. Analysis revealed significant differences in the fluorescence decay, band gap, and trap state luminescence emissions between the intact and degraded cadmium sulfide yellow across the painting. The results enhance our understanding of degradation pathways present in Femme, which is expected to help guide the painting’s future preservation. Moreover, data suggest that fluorescence lifetime imaging may provide a non-invasive mechanism for monitoring the state of preservation of cadmium sulfide painted layers.