Scientists have finally cracked the mystery why the vibrant yellows in impressionist painter Vincent van Gogh's paintings turned brown, according to AFP reports Monday.
A super-sensitive microscopic X-ray has revealed that a previously unknown chemical reaction triggered by sunlight caused yellow to degrade, according to the research findings published in the Analytical Chemistry.
The yellow pigment is called chrome yellow, and in a thin layer where the dried paint meets the surface varnish, sunlight penetrates the top layer of the paint and triggers the reaction.
Scientists believed the discovery may explain why some of van Gogh's most famous works no longer appear as they were originally drafted.
Apart from finding the answer to color deterioration, the research also sheds light on the protection and restoration of paintings.
"This type of cutting-edge research is crucial to advance our understanding of how paintings age and should be conserved for future generations," said Ella Hendriks of the Van Gogh Museum Amsterdam.
The study was jointly conducted by scientists from Belgium, Italy, France and the Netherlands.