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  • 7 messages
  • January 09, 2018 15:53
January 09, 2018 15:53

Dear fellow collector,

I thought I understood the luminescence of stamps. I understand the difference between fluorescent and phosphorescent I thought (phosphorescent glows after, when the UV lamp is extinguished in a dark room). I keep it close to home, and have a set of Gouda stamps (NVPH nrs 774-776), which are yellow fluorescent. I have a number of Juliana Regina stamps of eg 1 GLD (NVPH 952b) that are phosphorescent. So far I thought I got it.

Now I am currently researching a set of the serial number, eg 5 cents (NVPH 465). I have attached a picture of 3 different reactions under the UV lamp. According to the NVPH catalog, there is a variety at the 5 cent, No. 465b, on phosphorescent paper.

The left stamp in the photo lights up white, the middle one does not light up, and the right one lights yellow, The right one afterglows and is the variety 465b, is that correct?

Is my theory correct that the left stamp lights up because of the whitening agents in the paper? Do you call that fluorescence or not ?, but it is therefore not a variety, because it is not reported in the catalog?

Does anyone know from which year in NL there are whiteners in the paper?

A lot of questions, but I'm struggling with that right now, and hope someone can help me.

Mvg.,

Sandor

PS : unfortunately I was unable to attach a photo. Apparently not possible.

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az60
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  • January 09, 2018 20:23
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January 09, 2018 20:23

Dear svs.

I don't save the Netherlands, so I can't help you with the specific questions.

Do you call that fluorescence or not?

The lightening of the paper under a UV lamp, due to brighteners in the paper, is a clear case of fluorescence. However, this form of fluorescence is not listed in many catalogs. Only if the luminescent substances are specially applied and play a role in the postal automation process, will this be mentioned in catalogues. Catawiki may have intended it that way at some point, but did not provide a definition in the handbook. And so in my opinion all stamps with brighteners (which glow under UV) should be called fluorescent. Unfortunately, many people fill in 'none' for luminescence. A matter of copying from existing catalogues.

The increasing use of brighteners in stamp paper, from the mid-1950s to the early 1960s, may help to distinguish early editions from more recent reprints. Then there are paper varieties. Catawiki does recognize this variety, so many other catalogs do not or do not go into great depth. More information about luminescence outside Catawiki can be found here .

Incidentally, it can happen that the brighteners pull out of the envelope into the stamp.

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