I doubt if any self-adhesive gum will be water soluble at all. It's a question of chemistry, polar vs. unpolar solvents and all that.
What is water soluble, however, is a layer between the paper and the gum that is existent on some stamps, but not on others. In general, the very first US self-adhesive stamps as well as many (most?) of those that appeared from 2008 on cannot be soaked in water because they lack this layer. The same applies to UK self-adhesives from 2008 on, French and Italian ones. Maybe - just maybe - such a water-soluble layer will be (re)introduced. It would be nice, but I would not bet on it yet. Where did you read about this?
-jmh
Depends. US - I've not had too much luck with. French booklet stamps are, but not definitives (Mariannes). All Canadian are water soluble. UK - I've had some luck with commemoratives, but not with definitives.
-Darryl
Edit: Whoops. Meant to say that the layer between gum and stamp is water soluble in these cases.
As best I remember I think I either read on Linn's website or maybe even in one one of the U.S.P.S. Philatelic catalogs they send me. Am going to see if I can find the article.
Seems like I read somewhere that the gum on self-adhesive stamp was going to water soluble.
Is this true?
re: Next question: self-adhesives water soluble?
I doubt if any self-adhesive gum will be water soluble at all. It's a question of chemistry, polar vs. unpolar solvents and all that.
What is water soluble, however, is a layer between the paper and the gum that is existent on some stamps, but not on others. In general, the very first US self-adhesive stamps as well as many (most?) of those that appeared from 2008 on cannot be soaked in water because they lack this layer. The same applies to UK self-adhesives from 2008 on, French and Italian ones. Maybe - just maybe - such a water-soluble layer will be (re)introduced. It would be nice, but I would not bet on it yet. Where did you read about this?
-jmh
re: Next question: self-adhesives water soluble?
Depends. US - I've not had too much luck with. French booklet stamps are, but not definitives (Mariannes). All Canadian are water soluble. UK - I've had some luck with commemoratives, but not with definitives.
-Darryl
Edit: Whoops. Meant to say that the layer between gum and stamp is water soluble in these cases.
re: Next question: self-adhesives water soluble?
As best I remember I think I either read on Linn's website or maybe even in one one of the U.S.P.S. Philatelic catalogs they send me. Am going to see if I can find the article.