Over 125 years after Van Gogh had painted a series of his most recognizable works, 'Sunflowers', scientists discovered his key works began changing bright-yellow color due to exposure to energy-efficient lights installed in museums across the world.

According to experts, the bright-yellow pigment becomes unstable under LED lights and, over time, turns a shade of brownish green.

A sample of 14 works dated between 1887 and 1890 were tested for the reaction which affects the oil paint color known as chrome yellow, often used by 19th-century artists, including Paul Cézanne and Paul Gauguin, the Independent reported.

As a result, researchers had to warn museums to reconsider the use of LED lighting to prevent the colors in certain paintings fading away further and further.

"LED lights appear to have many advantages, but museums should carefully consider that paintings from the Van Gogh era could be affected by them," Claus Habfast, from the European Synchrotron Radiation Facility in France, told The Independent.

A team of scientists in France and Germany reportedly used ultra-powerful X-ray technology to analyze the bright-yellow tones in paintings by such luminaries as Van Gogh, Cézanne and Gauguin.

"We have found the unstable forms of chrome yellow in several well-known paintings, such as Portrait of Gauguin and the famous Vase with Sunflowers at the Van Gogh Museum in Amsterdam," Letizia Monico, a member of the research group that conducted the experiment, told the newspaper.

Van Gogh was determined to capture the sunflowers in a series of 12 pictures because the life-affirming yellow plants wilted very quickly.     
"I am working with the enthusiasm of a man from Marseilles eating bouillabaisse, which shouldn’t come as a surprise to you because I am busy painting huge sunflowers," the Dutch painter wrote in August 1888 when the sunflowers were in full bloom.

Van Gogh painted the series to please his friend, Paul Gauguin, and decorate the room where he would stay when he arrived in Arles. In the long run, Van Gogh created four sunflower still lifes, but felt only two were good enough to hang in Gauguin’s bedroom. He was later to paint three copies of them, one of which can be found in the Van Gogh Museum in Amsterdam.

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