A portrait of a woman has been discovered underneath a painting by Vincent van Gogh using new advanced x-ray analysis technology.

The discovery was announced on Wednesday by the Technology University in Delft, one of the institutes which carried out tests on the painting.
The new method measures the fluorescence of layers of paint which allows each type of atom, such as lead or mercury, and individual paint pigments to be individually examined.
The technology, which was developed by art historian Joris Dik at the Delft university and chemistry professor Koen Janssens of Antwerp university, was used for the first time on a work called Patch of Grass which was painted by Van Gogh in Paris in 1887.
Earlier research had already indicated the vague contours of a head underneath the finished painting but the new process is able to reveal this in ‘unprecedented detail’ say the universities in a statement.
It is well know that Van Gogh often painted over his works and experts estimate that around one-third of his paintings conceal other compositions.
The painting Patch of Grass is owned by the Kröller-Müller Museum in the Netherlands.
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