1991 topps glow back

[drcy]

Postage stamps have longwave (blacklight) and shorwave uv markers used for automatic sorting and mailing, and there are variations that are collected/valued by stamp collectors. Some of the variations are quite interesting.

[steve B]

Originally Posted by drcy

Postage stamps have longwave (blacklight) and shorwave uv markers used for automatic sorting and mailing, and there are variations that are collected/valued by stamp collectors. Some of the variations are quite interesting.

And, if you're into German stamps, some shades respond to UV, some don't. Some of the shades that do react are hard to find and a handful can be pretty expensive.

I also have a couple foreign stamps that are on paper that reacts, and one on an envelope piece that reacts. That one is from the 1880's.

On a crazy "steve" side not, some early US stamps also have shades that react or not, and I haven't found that listed in any catalog. Collecting is very different from one country to the next, stuff we tolerate is very much looked down on in most of Europe.