Toralf,
I know it sounds crazy - or maybe I am ;) - but the grooves at the front have NO effect on the UV-reaction. What HAS effect is what you can see when just looking through the stamp - from the front having a strong light source behind - and you can see irregular thin lines/curves or dots that are brighter than its surroundings. Hold this stamp under UV and use a magnifying glass to look at the front of this stamp. The earlier seen lines/curves and dots seem to react white whereas the darker surroundings react violet!
The so-called White just has a lot more of these white [on looking through] areas than the somewhat duller over-all reacting stamps. No matter how white, the violet areas can still be seen under the UV-lamp! And this is NOT just an Irish matter, I saw it in my Polish definitives as well.
And that is why I mentioned the colour red! The red shade [under UV] is quite significantly different for the W, W+/- versus the W+ and D in my 28p copies.
The more I discover the more questions arise! Why don't the grooves at the front have NO effect on the UV-reaction? Does the violet reflect the UV? And does that belong to the coating? Does that mean the coating filled up the grooves? And why not the white reacting areas visible when looking through?
Another aspect is that the Heritages stay flat after soaking off and drying them! I expected them to curl! The back of the stamps can be ultra flat with no grooves at all and giving a rather felt-like impression. To me the back side of the stamp is the felt side of the paper for sure, with the to be expected grooves at the front representing the wire side of the stamp paper!
The hollow grooves at the back do not occur that often as I would expect having
Rein
Barry,
Yes, not so private definitions :)
Optical Brightening Agents [chemicals] were used in the 1950-ies in washing powders to make everything "whiter than white". Underwear,shirts, etc.
Recycled textiles landed in paper pulp accidentally, but then also OBA's were added to paper pulp on purpose. By 1960 paper manufacturing was unthinkable without OBA's. Paper got coated more and more - glossy magazines - and while the coating hid the whitening of the pulp from the eyes, the coatings themselves needed the addition of OBA's.
Back to stamp paper.
Under the UV-lamp the philatelists could see no luminescence [reaction] up until the mid-1950-ies; they would'nt have done so at all hadn't it been for the postal administrations [Germany] starting to find ways of detecting stamps on cover - if they were there at all and where on the envelope so they could have the envelope thrown out or turned for the special machine to put the cancellations in the right place. One of the ways of detecting was to add (mainly) yellow reacting luminescent substances to stamp paper whether in the pulp or in the coating. OBA's were later added to the coatings as well - the machines were sensitive enough to tell the yellow reaction from the OBA's up to some point.
Anyhow, the (German) stamps being "fluorescent" caused the philatelist to use UV (around 1963 I did buy a special lantern with a black glass].
What could be seen?
Normal stamp paper having no coating reacted indifferent and looked yellow/brownish under UV till the mid-1950-ies.
After that, textile fibers reacting white could be found gradually more often, while OBA's added to the pulp also increased. In my studies of Dutch definitives in the early 1970-ies [1974] I used the following definitions:
D = dull , no reaction at all V0 = some white fibers added [the
Austrians use the term Leuchtfasern for their definitives!] - V3 - so
many fibers that you could hardly tell it from a paper which had just
OBAs added W = white under UV, both front and back [no coating!]
and virtually no fibers visible. The Canadians take the intensity into
consideration from low to high bright [hibrite].
So far just a single character!
The coating having had OBA's added to them as well needed a character too: D = dull, W = white. No fibers added of course so the V could be dismissed :)
I found combinations as follows:
D/D = dull coating / dull pulp [English coated paper used for a few 1950-ies Dutch and Colonies commemoratives]. W/W = both sides white under UV [Dutch paper used for Dutch Child Welfare stamps in 1961] D/W = dull at the front, white at the back [Polish commemoratives in the mid 1990-ies]
So far my "private definitions" that were necessary in order to describe UV-reaction BEYOND that for postal automation.
And thus far I had not studied the Irish stamps!
All definitions - also the single character - could be applied to Irish stamps as well. But as no Irish philatelist seems to have bothered to study this, nothing was found nor published.
The 1922-1966 definitives surely have D, V0, V1, V2, V3 and W and it is the highest time to find out. Coated paper in Irish stamps does exist since 1923!
D/D for the 6d definitive, the 2'6, 5' and 10' since 1937, the 6d 1945 Thomas Davis W/W for the photogravure stamps since 1962.
So far so simple, but then Toralf comes in!
In his article in the Revealer he discussed the gC3 and gC3a of the offset-litho printed Irish stamps. The "official" definitions led to a longish discussion between Tioralf and me about whether they are consistent and sufficient.
My point of view is that we should reach a universal definition as indeed there is something like a coating that has a "virtually no reaction" and I wanted to get into it more closely and having the UV-reaction of the back included in the study. Toralf thinks that studying the front would do. Not just for the general collectors but for the specialists as well.
We couldn't agree as to what causes the intermediate reacton of the coated front - or rather I am still not sure what it is! But it is there and not just ion Irish stamps as I have seen it in Polish definitives since the late 1970-ies as well. Of course, I had not observed it hadn't it been for this discussion!!
It seems that the whiteness of the pulp [hence V/W, where the W is a fact to be seen from the back under UV] shines through the coating OR the coating has OBA's as well. But added to the coating - an extra layer? hence my 'hue" or "veil" - reacts purplish but not everywhere on the surface hence "virtually no reaction".
The Canadian philatelist Chris McFetridge [Brixton Chrome] uses the term "dead paper" that reacts dull under UV but unlike the pre-1960 version, it "absorbs" the UV-light and appears purplish or violet. His observations point to the 1990-ies. I think Chris has observed the very same phenomenon as Toralf has! I did so as well as I described it for the Dutch commemoratives since 1998 when the paper of Tullis Russell was introduced. What happened was that OBA's got a bad reputation in the 1980-ies for their environmental evilness! And the OBA's got banned!
English stamp collectors found OBA-free paper in their Machin definitives.
Being detrimental to the environment the old OBA"s got replaced by other less detrimental substances so we can find nowadays stamps that glow enormously under UV [Dutch 2019 220 years of the Postal system] and I am sure that Irish commemoratives whether having been printed in Ireland or in England or elsewhere will show the new OBA as well.
As all we have discussed here is universally reflected in stamps all-over the world, we need universal definitions that can be applied everywhere!
And even the "Irish" CCP's can be used for post-1981 Irish stamps ONLY and not even for the pre-1981 stamp production! So, that is why I insisted all along this month-long discussion with Toralf to forget about CCP's and find a more adequate description of the various types of paper. Not withstanding the fact that for just Architecture or Heritage collectors this simplication will do!
And I am still discussing with Mexican collectors of the Exportas defiinitives [1975-1993], in which they see 14 subgroups based on differences in UV-reaction and gumming, about what are the intrinsic differences in paper once you forget the gumming [how to collect used stamps?] or the UV-reaction of OBA's [washed off used stamps suffer often the migration of OBA's from the cover!].
So, the theme IS universal. The Mexicans [and Canadians] have the SAME problem the Irish have ;)
The English do not bother as their Machin's offer them plenty of postal automation aspects to get confused :)
The Germans seem to have no problems here as the yellow fluorescence overrules everything! And who collects the Netherlands or Norway anyway?
Rein