Black light test

An ultraviolet light, it is used to authenticate paintings and other collectibles including art glass and porcelain. Ultraviolet rays react differently to various materials and reveal characteristics that are not visible to the naked eye. With the Black Light, one can distinguish between old and new and determine whether or not a work has been touched up or created recently when offered as antique. Modern paint becomes fluorescent under a black light, which, of course, can be the indicator that a work, described as much older, is in fact recently painted. Source: http://www.elac-llc.com/html/blacklighttesting.html