Ultraviolet light
ultraviolet light; the blue vertical
bands are fluorescent ultraviolet
tubes. Ultraviolet light (UV) is
invisible electromagnetic radiation with
a slightly shorter wavelength than the
visible light region of the spectrum.
Various colors of paint and layers of varnish fluoresce in different ways under UV light. This fluorescence can be photographed, both in color and in black and white. Recently applied paint absorbs UV and appears dark, allowing for the detection of areas of inpainting. Aged retouching, however, often goes undetected with UV. Examination under UV can sometimes also help in identifying pigments.
Continue.