In 2011, an article in the same journal from a team led by the University of Antwerp's Koen Janssens reported that a pigment Van Gogh favoured called chrome yellow degraded when other, chromium-containing pigments were present.

BBC: Van Gogh's Flowers In A Blue Vase damage seen in X-rays

When Stone Age man produced their remarkable cave paintings they often left handprints on the walls produced by blowing pigments from one hand through a tube held by the other hand.

BBC: Cave handprint, Montpellier University