This week, a long time coin collector, who recently has started collecting currency, asked me about ultraviolet lamps, and how they are used with Banknotes?
Longwave ultraviolet (or black light) is the popular name for
near-ultraviolet radiant energy, which falls just outside the visible
spectrum. When it falls upon certain materials, it makes them
“fluoresce,” that is, to “emit visible light.” What actually occurs is a
conversion of energy. The ultraviolet that is invisible, falls upon the
fluorescent surface and is absorbed and re-radiated at longer
wavelengths in the visibility range of the human eye.
I believe that having at least an inexpensive Ultraviolet Lamp is essential to enjoying the hobby to its fullest. I've been using a UV light since I was a kid.
It really opens up a whole new way of enjoying your collection. Best of
all, you can find all sorts of varieties that are not cataloged -
slight variations of color, completely different UV printing on what
appears in visible light to be the same note, etc.
Different countries use different papers and having the UV light is a wonderful to discover the
world of UV printed images on notes! Most countries around the world utilize some form of fluorescent
inks/paper to secure their issued currency. Some are seen using
shortwave UV, but most are able to be seen using the less expensive longwave UV light. Some are quite intense and
have various colors, while some are quite simple. Here is a
nice sampling of some of UV Banknotes from another IBNS member.
In a future blog, I will try to address watermarking on banknote paper.
