Modern US stamps versus the “Classics” present collectors with the opportunity to hunt for fun and interesting new varieties. Modern varieties can include tagging, die cuts, paper types and luminescent inks. This slides presented focuses on luminescent ink varieties specifically fluorescent ink varieties, where fluorescence is a specific type of luminescence.
Most of the inks used for printing US stamps are not luminescent, but there are many that are printed with one or more luminescent inks. Those printed with one or more luminescent inks were inks are most likely chosen so that specific a color(s) appears brighter under normal visible light. In these cases all of the stamps in that issue are printed with the same fluorescent ink. A great example is the1988 Carousel Animals issue. What doesn’t appear to be typical is to find the same US stamp issue printed with both luminescent and non-luminescent inks.
Fluorescent inks are made from on pigments that have the ability to absorb Long Wave Ultraviolet (UV) energy and re-emit this energy within the visible spectrum. The effect of this is to cause the ink to “glow” and typically appear bright to very bright under under Long Wave UV lighting. A common example of images printed with luminescent inks are “Black Light Posters”, which many have probably seen in one form or another. The light used for illuminating “Black Light Posters” can also be use to identify stamp luminescent ink varieties. A great low cost source of lighting for identifying luminescent ink varieties is specifically an 18” fluorescent black light tube. UV LED lighting does not work very well since the light isn’t filtered and incandescent black lights do not work at all.
Scott’s Specialized Catalog of US Stamps identifies a small number of stamps with luminescent ink, but the vast majority are unlisted. What little information that has been published on this topic is associated with luminescent ink used for tagging and the automated sorting and canceling of letters. As a result the vast majority of the stamps presented are not known to collectors. The presentation provides a visual reference of the known varieties that have been identified so far. More are yet to be discovered.
This can be a great way to introduce younger people to stamp collecting as the bright colors can be especially appealing and eye catching. Collectors of World Wide stamps will also find this same phenomenon exists with stamps printed by other countries. So get out those “Black Lights” and happy hunting.
A special thanks goes to Hans Van Gils in the Netherlands who has contributed to the identification of these varieties.
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