14 February 2011
Vincent van Gogh is perhaps best known for his sunflower paintings, but a recent scientific analysis has revealed unsettling evidence that Van Gogh's sunflowers are slowly turning brown.
A team of scientists led by Koen Janssens at the University of Antwerp have discovered that sunlight produces a chemical reaction within Van Gogh's sunflower paintings. Van Gogh used a sulphate-based white pigment in order to lighten the shades of yellow in his famous sunflower paintings and it's this pigment that now leaves the works vulnerable to discolouration.
At the European Synchrotron Radiation Facility in Grenoble, France Janssens' team used a high energy x-ray to analyze paint samples and found that ultraviolet light caused the paint to turn to a chocolate brown hue.
Janssens believes that the rate of discolouration can be slowed if the paintings are protected from sunlight and ultraviolet light and kept at cool temperatures.
The research was published in the journal Analytical Chemistry.