Van Gogh's painting grounds: an examination of barium sulphate extender using analytical electron microscopy - SEM/FIB/TEM/EDX

We have investigated the potential of utilizing analytical electron microscopy to quantitatively examine the microstructure of the grounds used by Van Gogh and, in particular, the nature of the barium sulphate used. Samples from three paintings from the French period were examined with the aim of determining whether the barium sulphate was the same in all three paintings. The results reveal differences in the size of the barium sulphate as well as the presence of varying amounts of strontium in the barium sulphate. The presence of strontium indicates that the barium sulphate is of natural origin i.e. barite. We have found differences in both the overall strontium concentration in the barium sulphate crystals from different paintings as well as variation within a painting itself. We tentatively conclude that the barium sulphate is different in all three paintings. The results are part of a more quantitative method of comparing and classifying paint cross-sections which will supplement the more traditional qualitative approach. It may also help to identify the actual source of the barite although more samples will have to be examined. The information obtained from this study is being used to add to our knowledge of the methods and materials used by van Gogh, which is helping in the reconstruction of Van Gogh's oeuvre and attribution.