angore
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What I collect: WW, focus on British Empire
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Post by angore on Mar 15, 2020 11:24:03 GMT
Here is a video of phosphor after glow on a Machin stamp. Now Deegam says the yellow is not a phosphor but just fluorescent.
Lighting - shortwave
2-band - yellow
Speed - 1/4 actual speed
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susiecc
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What I collect: General US, Precancels, Monaco, India Feudatory States, the World!!
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Post by susiecc on Mar 15, 2020 11:50:48 GMT
Hello. I'm very unfamiliar with Machin stamps. I had to look it up. Is the afterglow you talk about a postal cancel? or?
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angore
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Post by angore on Mar 15, 2020 12:33:57 GMT
Many stamps have some phosphor coating that is used to find the stamps on mail and cancel them using automated equipment. Depending on country and chemistry of coating used, you can see the effects under long wave and short wave UV lamps.
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susiecc
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What I collect: General US, Precancels, Monaco, India Feudatory States, the World!!
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Post by susiecc on Mar 15, 2020 12:39:21 GMT
Thank you angore!
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brightonpete
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Post by brightonpete on Mar 15, 2020 13:34:34 GMT
That is like the "Winnipeg" tagged stamps of Canada. The UV light would shine on the stamp, then the after-glow would be picked up by the cancelling equipment. It was ultimately abandoned, with the "Ottawa" tagged version, later called "General." General (Ottawa) tagging just fluoresces when the UV light shines on it, no afterglow with these.
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