New X-ray technique reveals colour of hidden van Gogh

From The Telegraph: New X-ray technique reveals colour of hidden van Gogh.

A portrait of a woman by Vincent van Gogh that he later painted over has been revealed in more detail than every before thanks to a new X-ray technique.

Previous research had discovered an outline of the peasant’s head behind the Dutch painter’s later work, Patch of Grass.

But this latest technique, which has never been used before, has unveiled the pigments van Gogh used in the original painting.

Over two days the scientists bombarded the painting with a powerful pencil-thin beam of X-rays, which caused the atoms in the picture to release "fluorescent" X-rays of their own which the scientists measured.

As the different chemicals that van Gogh used to paint the image release differing amounts of fluorescence, they were able to map the picture in great detail. [continue]