Ultraviolet fluorescence imaging
Certain substances are differentiated from others by their capacity to fluoresce in the visible region of the spectrum when they receive UV wavelength between 300-400nm. A such, damaged or over-painted varnish layers on surface of art works are is easily and quickly traced since varnishes, older or newer, fluoresce, while losses of varnish due to wear or subsequent procedures present as dark areas with zero fluorescence. This is also one of the most interesting techniques for studying certain organic materials, mainly pigments and binders. The image obtained through the application of this technique is a color visible image, despite the fact that the lighting sources used emit ultraviolet radiation.