It would appear that in this instance Vincent van Gogh’s art is imitating life.
Conservationists have long been interested in finding the reason why some of van Gogh’s paintings of vibrant, yellow sunflowers have been turning brown over time and they seem to have a made a breakthrough. It seems that van Gogh occasionally mixed his yellow paint with white powders in order to brighten the hues. Unfortunately, since the white powders were sulfate-based, over time, the addition had a reverse effect.
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As the Guardian reports, “The researchers found that sunlight kicks off a chemical reaction that ultimately turns yellow paint brown. The sunlight oxidises the oil in the paint, releasing electrons. These are then taken up by the yellow pigment – lead chromate – turning it green. The mix of green paint with oxidised oil produces a chocolate brown color.”
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The research was led by Koen Janssens at the University of Antwerp and the findings were published in the journal Analytical Chemistry. “By mixing these white powders in, van Gogh intended to make a lighter yellow paint, but through this effect, nature darkens it,” Janssens said. “While he wanted to show a light, pale and delicate yellow, it instead becomes a darker, brownish yellow.”
So just as real sunflowers brown over time, so do van Gogh’s. Luckily for art lovers, the paintings can be preserved by keeping the paintings shaded and in cool temperatures. (via Guardian)