Chalky Stamp Paper

Some catalogs, especially Stanley Gibbon's, list Chalky Paper vs. Regular Paper as a variety. What is the best way to identify a Chalky Paper?

What country? Paper varieties can be very misleading. It often depends on what part of the world the stamp is from that will provide you an answer.

As wt1 noted, chalky paper has no standard. In most cases, you can sort of see "sheen" if you tilt the stamp under a good light. But that is not always the case. It's much easier to see on mint stamps. If you can compare the same stamp that was issued both on normal and chalky paper, then you'll have a better idea what to look for.

I am told that rubbing the edge of a silver coin or using a silver wire, will leave a gray mark on chalky paper and nothing on normal paper (unless the coin/wire is dirty, of course). I've never bothered to do that, so I don't know if that test is "reversible".

WT1--In particular I'm asking about the Portugal and Portuguese Colonies Ceres stamps, but S.G. uses the term Chalky Paper though out their catalogs. I have heard of the silver streak test before, which is fine if you have two copies as I know of no way to remove the streak. The difference between Chalky Paper and Regular Paper can sometimes make quite a difference in the value of a stamp. I'm looking for a way to tell the two papers apart without damaging the stamp.

This doesn't really help much to answer your question other than what was stated earlier, but here's a previous thread on the subject you may want to look at. One thing that wasn't mentioned above is that a UV light can be a good detector of "chalky paper":

https://goscf.com/t/5770

Once upon a time, I saw a photo of old Swiss definitive stamps under magnification that showed the great improvement in printing quality with chalky paper. The paper surface on chalk-coated paper is much smoother and the resulting print quality is far sharper - regular paper under high magnification is full of bumps and pits and chunks of fibre and so on, and the print quality suffers because of that. I expect the comparison I saw was on typographed stamps - the large fields of solid colour are noticeably different with the two papers, as the imperfect surface of regular paper results in a poorer, irregular print. But I can't find that example on a quick search now - not in Michel specialized, not in Zumstein, not in SBK, nothing popped up on image searches for "Kreidepapier" or "gestrichenes Papier" or "chalky paper" or "coated paper". Oh well.

The idea of scratching a stamp with a silver coin is just a Mohs hardness test - chalk is harder than unalloyed silver (generally), so the stamp acts sort of like sandpaper, scratching off a small amount of silver.

I've heard that you can tell chalk-surfaced paper by rubbing the surface lightly over your lip - presumably the smoother surface can be detected, if you don't live in Calgary in the winter where it's -30° C with 5% humidity inside the house and lips chapped to the point where they're about as smooth as my heels ....

Ryan

I know that some of the early Russian stamps (Tsar times) used chalk to prevent people from soaking and postally reusing them.I've got a couple of them that were soaked off the paper and the ink has faded.

wt1--Thanks for the link to an earlier thread on the subject. I'll try the UV light suggestion and see how it works. There are some Portuguese Colonies Ceres stamps that were ONLY printed on Chalky Paper, so I'll compare one of those with one the was only printed on normal paper and compare them. I hope it works as the streak test, while it does work, is not viable as it permanently damages the stamp.