We have investigated the potential of utilizing analytical electron microscopy to quantitatively examine the grounds used by van Gogh and, in particular, the absolute amount of extender employed. To determine the accuracy that can be achieved, a series of oil paint reconstructions were used as standards. The proportion of extender was measured using scanning electron microscopy and energy dispersive X-ray spectroscopy, and a relative error of 10% or better was achieved. The same method was then used to determine the ground composition of real samples from van Gogh paintings. The results obtained in this work are part of a more quantitative method of comparing and classifying paint cross sections, which will supplement the more traditional qualitative approach. 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.
