image creditResearchers have spotted a never-before-seen chemical effect in Vincent Van Gogh's 'Flowers In A Blue Vase' that is dulling the work's vibrant yellows. It seems a layer of varnish added later to protect the work is in fact turning the yellow to a greyish-orange color.
High-intensity X-ray studies described in Analytical Chemistry found compounds called oxalates were responsible. But atoms from the original paint were also found in the varnish, which may therefore be left in place.
