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PostPosted: Fri Sep 04, 2020 9:22 pm 
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Joined: Sun May 03, 2020 11:19 am
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During a session of soaking off some Harrison Machins, I noticed after using tissue paper as a source for drying them that the tissue had become impregnated with a fluorescent substance, and could only presume that the fluorescence had come from the surface that the stamps and been initially coated with, concluding that this fluorescent substance was highly fugitive once moistened and could easily contaminate the stamps in soak.
This is the tissue in question and my observation under UV as to it's condition after use, here is an attachment attributed to that fact .....,

After seeing the tissue, I then decided to examine some of the stamps, again under longwave ultraviolet light and discovered that they had also been affected by their coating once submerged in water, as can be seen in the next attachment.
(186.66 KiB)

Is there a way to prevent this from happening other than by sweating them off individually ?
Another important question is "Was the substance used toxic" ? WM.

Last edited by Wilding Mad on Sat Sep 18, 2021 12:21 pm, edited 2 times in total.

PostPosted: Thu Sep 10, 2020 10:02 am 

Joined: Fri Nov 02, 2012 7:00 pm
Posts: 67
Location: East Anglia

QV surface-printed stamps have very fugitive ink, but it never occurred to me that there might be a problem with the coating of early decimal Machins, not just to the stamp being soaked but its companions in the soak.

Would floating them face up on the surface of the water, letting the water seep through from below, with individual rinsing, reduce the problem to acceptable levels?

As to toxicity, I would not have thought there was any, even though H&S was not so important almost 50 years ago. Or if there was, not enough to harm humans. But best perhaps not to let your dog/cat/fish drink/swim in the residual water.

PostPosted: Thu Sep 10, 2020 11:05 am 
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Regarding toxicity: while I don't have data on this specifically (other than a general recollection that toxicity was one reason for not using inorganic phosphors), I did come across a c.1970 report in the PO archives analysing the gum on some registered envelope flaps that contained a trace of arsenic.

The conclusion there was that it wasn't remotely enough to cause a problem even if someone licked lots of them, but it was certainly enough of a concern that they were testing the gum. So I expect that any substances used as phosphors were tested for toxicity beforehand.

PostPosted: Thu Sep 10, 2020 11:12 am 
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Good morning Winston,
Your method of soaking off in order to prevent contamination occurring sounds helpful and I could also add that the stamp be removed from it's paper ASAP once removable to prevent further contamination.

I suppose that by now millions of these stamps from this particular era will have already been processed (soaked off) and their owners are unaware of their condition, especially if they don't have a longwave 'black light' to hand.

It would be interesting to hear from other collectors with similar findings to add to this particular topic.

Thank you also Moz regarding possible toxicity of gum.

Perhaps due to some of the factors mentioned the self adhesive was introduced on October the 19th 1993 and fluorescent surfaced papers were no longer produced from 1992 onwards due to changes in technology and possibly environmental aspects as an improvement.

But even then with their new technology, the Royal mail still have to rely on the local postman to cancel some of their mail !

What a farce, WM.

PostPosted: Thu Sep 16, 2021 9:45 am 
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Soaking the 17p Dark Blue Machin centre band off paper.
The use of the long wave ultraviolet lamp has many advantages in detecting fluorescence in papers, but whilst soaking some stamps off paper I noticed a very peculiar reaction in that when the stamps were wet and laid out to dry on a tissue paper, a definite difference was noticed between two different types of paper that they had been printed on, and with a little experimentation in combination with a long wave UV light I soaked off some 17p dark blue Machins with centre band and compared the differences found in combination with the use of long wave ultraviolet light, note that both types of paper had equal soaking time. Therefore I was quite amazed with the outcome as the damp translucent type stamps showed a high degree of fluorescence whereby the damp more opaque looking ones gave a very weak reaction giving rise to the fact that two different papers had been used to print these stamps, this reminded me of the cream and white versions of the earlier multiple crown Wilding definitives listed in the SG part 3 specialised catalogue.

Below you will find three examples of these particular 17p stamps as seen under different exposures of light.

Item 1. As seen under artificial light (fluorescent lamp).

Item 2. The same stamps but using a light combination.

Item 3. The same stamps but under long wave UV only.

This experiment is only recommended for used stamps, but it does show you the vast difference found using the damp paper method, try it for yourself on this and other values and see what you can discover !

Note: Once the stamp paper had dried no difference was noticeable in the visible spectrum between the two variations discovered, but the difference could still be observed using long wave UV.

The magic is in the water !!!!!

Here is another issue concerning the 1990 17p Christmas stamp with similar characteristics using the damp paper method and L/W UV, it can be seen that the damp translucent paper is fluorescent whereby the damp opaque paper is non-reactive under L/W UV. >


If all of the different coatings have been listed such as OCP, FCP, PPP, PCP l & 2, ACP, etc.
Then shouldn't the different types of base paper being used also be included irrespective of the coating ?

Another value I discovered being on different papers whilst using the damp paper method was the 15p "Harrison" centre band stamps, after soaking them off paper I placed 3 of each of the two types of paper discovered (opaque and translucent) on a separate piece of tissue still damp and took images of them, one under fluorescent light the other under L/W ultraviolet, as you can see there was a major difference in their response to ultraviolet, the reaction is not because of a coating but of the actual base paper itself produced and used in the printing of these stamps. <see images >


A problem which I thought had previously been rectified with the additional use of optical brightening agents or oxidation seems to have appeared once again in the form of a contaminated paper that contains fluorescent fibres, this contaminated paper has been used to print the 1990 15p 150th anniversary of the first adhesive postage stamps, I am sure that once you have seen them personally you will be in agreement that they are reminiscent of some of the multiple crown Wilding stamp papers exhibited in another posting I recently made. >


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