Thursday, March 13, 2014

Forged painting revealed by isotope analysis

The Contraste de Formes, now considered a fake.
Source: European Physical Journal 
There's a great detective story in the January issue of European Physical Journal, showing how a painting attributed to an artist can be proven to be a fake. The cotton fibers of the canvas in question showed the carbon-14 signature of the atomic age atmospheric tests, and the painting must therefore have been made after the death of the artist.
From about 1950 to 1963, testing of atomic bombs generated large amounts of carbon-14 in the atmosphere, sharply increasing the ratio of this isotope to the more common carbon-12. This atmospheric carbon-14 was taken up by living things worldwide, creating an unmistakable isotopic signature of the atomic era. This "bomb effect" carbon has been used to identify poached ivory , to give evidence for the birth of new neurons in the adult human brain, and to reveal a supposedly ancient mummy as a modern fake.
In the recent paper, the authors examined a canvas, Contraste de Formes,  in the Guggenheim collection in Venice. This canvas was purportedly one of a known series of paintings by this name painted by Fernand Leger, a cubist artist, between 1912 and 1914. Even in the 1970s, the owners of the painting had had some doubts about its authenticity.  This work was painted on cotton, not linen, and used different pigments for some colors compared to others in the series known to be from Leger. But these differences could not settle the question of whether Leger had painted it.
 In the new scientific study, the authors took a snippet of canvas and analyzed it for the carbon 14/carbon12 ratio. They found that carbon-14 was more than 40% higher than would be expected from a pre-atomic age item. Instead, the cotton plants used to make the canvas had to have been harvested in  1959 at the earliest. This final date settled the authorship question, as Leger died in 1955! The painting has to be a fake.

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