An international team of Italian, French, Belgian and Dutch scientists has discovered a chemical reaction that explains why the intense yellows in the works of the Dutch painter Vincent Van Gogh turned brown . Specifically, tests with an ultrasensitive microscopic X-ray revealed a chemical reaction triggered by sunlight that causes the yellow to fade, according to a study published in the journal Analytical Chemistry .
"This kind of cutting-edge research is crucial to advancing our understanding of how paintings age and how they should be preserved for future generations," explains Ella Hendriks of the Van Gogh Museum in Amsterdam.
Studies, carried out at the Grenoble synchrotron in France, showed a reduction in chromium , "especially noticeable in the presence of chemical compounds containing barium and sulfur", which converts chromium yellow into brown pigments. That observation led scientists to suspect that "Van Gogh's technique of mixing white and yellow paint could be the cause of the darkening of his yellows."
