Today I received a postcard from China. Not in itself a rare thing, but I'm glad to see mail from China has resumed, after being stopped for a time after confusion resulting from the de minimis duty changes. No, this card had a unique feature: stamps with fluorescent ink. When I shined an ultraviolet light on them, unseen features appeared. (I am a research scientist, and use a UV light in my daily experiments in the laboratory.) The sender of the card explained that the stamps showed prehistoric fossils, and under UV light, the location where they were discovered is revealed. Pretty nifty! Even the other stamps, like the one on the lower right, with the large Chinese characters and the '3' on it had some fluorescent security features embedded in it. This is the first time that I'm aware of fluorescent ink being used in stamps. However, nearly invisible fluorescent barcodes have been applied to mail by the USPS to aid in sorting for many years.
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Stamps under normal light.
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| The same stamps under ultraviolet light. |
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