http://www.kunsthaus.ch/en/the-collection/conservation/examples-from-the-world-of-art-conservation/the-zurich-master-of-the-carnation/fig2/?redirect_url=title%3DRessources

Kunsthaus Zürich

The Zurich Master of the Carnation

General view, UV fluorescence image
When exposed to UV light, retouching and reworking show up in a different colour from the original painting.
General view, UV fluorescence image
When exposed to UV light, retouching and reworking show up in a different colour from the original painting.