Some of Vincent Van Gogh’s most famous paintings are of sunflowers. Sunflowers were especially important for Van Gogh. For the French artist, sunflowers represented happiness and loyalty. But Van Gogh is also famous for the intensity of his colours. Van Gogh particularly loved using vibrant yellows in his paintings. Sadly, some of these bright colours are going dull and turning brown. Art historians, conservationists and scientists are desperate to understand what is causing these changes in colour.

During the 19th century, artists experimented with new chemical colour pigments. Van Gogh particularly favoured chrome yellow which darkens in sunlight. However, some yellows used by Van Gogh are darkening faster than others. To find out why this is happening, scientists took samples from three different tubes of historic chrome yellow paint. The scientists then exposed the paint to intense UV light to simulate the ageing process.