How cat hair brought down a pair of art forgers

Featured on sciencemag.org

When a curator at Yale University started digging through his gallery’s storage space, he wasn’t expecting to find anything special. But within the piles of mediocre works, a 1.5-meter-tall canvas caught his eye. Called The Education of the Virgin, it depicted a very young Virgin Mary being taught to read by her parents, St. Anne and St. Joaquim. Its surface was badly damaged, with cracked paint and parts of the image worn away. Even still, the curator thought he recognized the hand behind the painting: The 17th century Spanish master Diego Velázquez.

But how to know for sure? Today at the meeting of AAAS (publisher of Science) here, researchers discussed how scientific analysis can help identify the artist behind a painting, even when his or her identity has been lost for centuries or millennia.

In the case of Velázquez, researchers had previously identified certain quirks that show up again and again in his paintings. Although green pigments and dyes were available in 17th century Seville, where he worked, Velázquez preferred to create his own greens by mixing blues and yellows. When researchers analyzed the material used to create St. Joaquim’s green robe, they found a mixture of calcium carbonate (yellow) and the copper-based based pigment azurite (blue). The cracked surface of the painting also revealed the fine lines that the artist sketched on the canvas to guide his hand while painting the image, a technique that Velázquez is known to have employed.

“If the top layer [of paint] were completely undamaged, it would be impossible to see this,” says Ian McClure, an art conservator at Yale. (He wasn’t the one who found the painting, but he helped lead the team that analyzed it.) And when his team took an x-ray photograph of The Education of the Virgin, they saw that an earlier version of St. Anne’s face had been scraped off and redone. Lesser imitators (or outright forgers) of Velázquez were very unlikely to show that attention detail, McClure told the audience. “This painting is very unlikely to be a copy … This is very much the artist in process.”

“Taken on their own, these materials and techniques are not unique fingerprints to Velázquez,” says Anikó Bezur, a conservation scientist at Yale who worked with McClure. But taken as a whole, she says, all the evidence “knits together” and “adds considerable force to the attribution of this painting to him.”

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