A joint application of ATR-FTIR and SEM imaging with high spatial resolution : identification and distribution of painting materials and their degradation products in paint cross sections

A series of paint cross sections from an oil painting are studied by attenuated total reflection in conjunction with Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). The imaging modes of both methods were employed to show their potential in the detection of various painting materials and their distribution in the paint cross sections. The goal of this work is to evaluate FTIR and SEM-EDX spectroscopy in order to understand the limitations and strengths of both approaches. It has been revealed that both techniques are complementary in the identification of pigments, extenders and binding media used by an artist. FTIR spectroscopy is also a powerful tool in the studies on degradation products that are formed due to ageing or deterioration of works of art. We attempted to identify such secondary products present in the paint cross section. Cadmium oxalate and a high concentration of zinc palmitate/stearate were detected for the first time with the use of ATR-FTIR imaging technique. These results can complement studies on the conservation issue and provide an insight into understanding the mechanisms of chemical processes that appear in art works.