The panel under ultraviolet light
ultraviolet (UV) light. Newly applied
materials, including retouching, absorb
UV radiation, and will appear as dark
spots. On the surface of Portrait of a Man
a large number of scattered small areas
of retouching are revealed
under UV light.
Older retouching does not absorb UV radiation, and may thus go undetected. In Portrait of a Man, an area of extensive repainting was observed around the join between the two boards, but this area fluoresces under UV light. This indicates that the cropping of the panel, and the subsequent restoration, must have occurred relatively early in the painting's history.
Visible Ultraviolet Infrared X-ray Verso