Ater-treatments of stamp paper before printing

[Rein]

The production of stamp paper in sensu stricto ONLY deals with the base paper it self including watermarks and meshes.

All later treatments like coating and gumming etc. are discussed in philatelic literature with a lot of ideological cults.

British Commonwealth collectors know only chalky and ordinary paper, the KGVI collectors get trapped in the dichotomy and come up with "substitute" paper and even "thin striate".. And don't you dare to question their definitions!

Similar discussions - or rather not discussions - can be read about "ribbed" papers.

Portuguese collectors come up with very copious descriptions like "papel porcelana" ...

I will try to get a start here in describing some of the phenomena I met in the field of the after-treatment of stamp paper!

As a teaser some BMA!

[Rein]

Ordinary paper is just paper without any later treatments like calendering, coating, varnishing, controll marks, etc at the front nor coating or gumming [plus breaking] at the back.

Aspects like watermarks and meshes, thickness, flexibility or additions to the paper pulp are NOT dealt with in this thread.

When talking about "ordinary" paper, you have to add the extra information apart like: red coloured (ordinary) paper, (ordinary) paper with yellow fluorescence added in the pulp, etc....

Hand-made paper versus machine-made paper is relevant with stamps in the pre-1860 period or produced in Farabroadistan, as machine-made is assumed in practically all cases. But even then, how do we know for sure that i.e. 1852 The Netherlands was on hand-made paper?!?!?

Direction of paper can be established in ALL machine-made papers - no excuse for not doing so! The easy way of have the stamps curl a bit is NO proof! I will get into that later on ...

[Rein]

One of the first treatments stamp paper got was calendering:

https://en.wikipedia.org/wiki/Calender

A calender is a series of hard pressure rollers used to form or smooth a sheet of material such as paper or plastic film. In a principal paper application, the calender is located at the end of a papermaking process (on-line). Those that are used separately from the process (off-line) are also called supercalenders. The purpose of a calender is to make the paper smooth and glossy for printing and writing, as well as of a consistent thickness for capacitors that use paper as their dielectric membrane.

The problem we have with calendering is that it can be observed by looking at a stamp front surface under some angles, but that I see no way of catching it by ways of photographing or scanning.

Another problem is that the effect disappears often in used and washed off stamps...

[Rein]

In the early 1980-ies my friend Huig Tielman and I discovered the presence of diagonal patterns at the front of Dutch stamps that had been printed on coated paper delivered by Harrison & Sons ... We called it "glansdiagonalen" or "gloss diagonals". Of course you could see it when looking at the stamps under some angles, but we no way of making it visible for others to see ...

Now, I think this pattern comes from the cylinders that were used for calendering. Even though it was done not directly after the reel of paper came off the sieve, but later on - after coating and before printing! Even the word "gloss" was inadequate as the Harrison&Sons paper was matt! We took care of not confusing these patterns with those that might arise from the meshes. The angles of the diagonals - with the "horizon" across the directon of paper - were mainly -30/+60, -40/+50, -50/+40, -60/+30 or about ....

Similar diagonal patterns we discovered in German definitives in 1970-2001 period printed in typography or recess on uncoated paper! The origin of these patterns as coming form calendering was more plausible. The patterns were often better visible than that of the paper mesh!

I have good hope that I will manage to make these (German) patterns visbile someday by scanning

[Rein]

The better known application is the gumming at the back of a stamp. Hardly any stamp now was issued without and there is long tradition from manual application to having self-adhesives. A sub-subject on its own to be dealt much later.

Used stamps should have no gum and therefore can't really tell us in what original state our stamp paper was

Gum arabic used to crackle and with changing climatic conditions made sheets of stamps curl. In order to have sheet stored properly, the gum was often broken mechanically. This gum-breaking could give very distinctive charaacteristics even visible in the stamps long affter the gum had been removed. Therefore I'd like to treat the effects of gum-breaking in this thread although strictly spreaking it was NOT an after-treatment of the paper...

Germany:



Austria - visible even at the front:



Argentina the same: