A new technique allows pictures which were later painted over to be revealed once more. An international research team, including members from Delft University of Technology and the University of Antwerp, has successfully applied this technique for the first time to the painting entitled ‘Patch of Grass’ by Vincent van Gogh. Behind this painting is a portrait of a woman.

It is well-known that Van Gogh often painted over his older works. Experts estimate that about one third of his early paintings conceal other compositions under them. A new technique, based on synchrotron radiation induced X-ray fluorescence spectroscopy, reveals this type of hidden painting. The techniques usually used to reveal concealed layers of paintings, such as conventional X-ray radiography, have their limitations. Together with experts from the Deutsches Elektronen-Synchrotron in Hamburg and the Kröller-Müller Museum, TU Delft materials expert and art historian Dr Joris Dik, and University of Antwerp chemistry professor Koen Janssens therefore chose to adopt a different approach. The painting is subjected to an X-ray bundle from a synchrotron radiation source, and the fluorescence of the layers of paint is measured. This technique has the major advantage that the measured fluorescence is specific to each chemical element. Each type of atom (e.g. lead or mercury) and also individual paint pigments can therefore be charted individually. The benefit of using synchrotron radiation is that the upper layers of paint distort the measurements to a lesser degree. Moreover, the speed of measurement is high, which allows relatively large areas to be visualised.

(Link and photo: eurekalert.org)