UV-detection

At bank notes and other securities printing they use fluorescent dyes, i.e., dyes capable to glow under exposure to UV-radiation. To give a dye such a property, they add special components into it - luminescent solids that do not glow in natural light, but under exposure to UV-radiation there appears luminescence of one or other colour called fluorescence.

Because of fluorescent dyes availability, at present there appeared counterfeits wit imitated protective elements done with such dyes. A counterfeit picture luminous under exposure to UV-radiation may differ from an authentic one with its form, position, glow tint or colour hue, as well as sometimes it may be seen both from the reverse side of bank note (in a case of dye penetration into paper).

In rare cases a fluorescent picture on authentic bank notes may be absent or be almost inperceptible because of defective production. Besides, an imprint glow in UV-rays may disappear in the course of time because of pigments-luminescent solids wear in the process of a longterm circulation of a bank note or after its being in an aggressive environment.