Verdigris Spots?

[declanwmagee 122]

Incidentally, talking about slabs, does anybody know if any form of spontaneous or continued deterioration, can occur in the slab ? Or does the act of slabbing arrest the action of any deleterious outside agent already on the coin ? Probably sounds a naive, simplistic question, but I'm no metallurgist.

Pretty sure, '49, that anything that had started already, could easily continue. They don't seal 'em in argon, it's just air in there as far as I know.

[Sword 1,330]

You would'nt buy blind on ebay, so why buy blind in another auction. A bit like Russian roulette if you ask me, you never know what you're going to get. Verd is copper disease, not silver, so i'd also go with the plastic reaction. It should make the slab buyers worried, especially the top end slab buyers of silver

Yes, I always thought that verd was a copper, bronze & nickel brass issue, rather than a silver one.

Had a strange experience with my uncirculated 1919 shilling a few months back. Took one of the shilling drawers from my cabinet, and noticed what ~ for all the world ~ looked like green verd at the base of the 1919 shilling reverse. On removing the shilling, and very lightly rubbing the base of the shilling, the green material just fell away as though it was powder. Obviously it wasn't verd, but quite what the hell it actually was, I've absolutely no idea. No residue was left behiind.

Incidentally, talking about slabs, does anybody know if any form of spontaneous or continued deterioration, can occur in the slab ? Or does the act of slabbing arrest the action of any deleterious outside agent already on the coin ? Probably sounds a naive, simplistic question, but I'm no metallurgist.

If there is a harmful chemical already on the coin (but initally undetected), then there is no doubt that slabbing cannot prevent it from reacting with the metal in due time. The link in my last post describes a situation where a spot (damage due to previous long term contact with PVC) only developing after the coin has been slabbed. However, I do think these cases relatively uncommon. Obviously, such coins will develop problems whether you slab them or not and so slabbing cannot be blamed for the issues.

[Gary1000 41]

You would'nt buy blind on ebay, so why buy blind in another auction. A bit like Russian roulette if you ask me, you never know what you're going to get. Verd is copper disease, not silver, so i'd also go with the plastic reaction. It should make the slab buyers worried, especially the top end slab buyers of silver

Yes, I always thought that verd was a copper, bronze & nickel brass issue, rather than a silver one.

Had a strange experience with my uncirculated 1919 shilling a few months back. Took one of the shilling drawers from my cabinet, and noticed what ~ for all the world ~ looked like green verd at the base of the 1919 shilling reverse. On removing the shilling, and very lightly rubbing the base of the shilling, the green material just fell away as though it was powder. Obviously it wasn't verd, but quite what the hell it actually was, I've absolutely no idea. No residue was left behiind.

Incidentally, talking about slabs, does anybody know if any form of spontaneous or continued deterioration, can occur in the slab ? Or does the act of slabbing arrest the action of any deleterious outside agent already on the coin ? Probably sounds a naive, simplistic question, but I'm no metallurgist.

If there is a harmful chemical already on the coin (but initally undetected), then there is no doubt that slabbing cannot prevent it from reacting with the metal in due time. The link in my last post describes a situation where a spot (damage due to previous long term contact with PVC) only developing after the coin has been slabbed. However, I do think these cases relatively uncommon. Obviously, such coins will develop problems whether you slab them or not and so slabbing cannot be blamed for the issues.

Perhaps the coin should get a good dip before slabbing

[1949threepence 3,366]

Incidentally, talking about slabs, does anybody know if any form of spontaneous or continued deterioration, can occur in the slab ? Or does the act of slabbing arrest the action of any deleterious outside agent already on the coin ? Probably sounds a naive, simplistic question, but I'm no metallurgist.

Pretty sure, '49, that anything that had started already, could easily continue. They don't seal 'em in argon, it's just air in there as far as I know.

If there is a harmful chemical already on the coin (but initally undetected), then there is no doubt that slabbing cannot prevent it from reacting with the metal in due time. The link in my last post describes a situation where a spot (damage due to previous long term contact with PVC) only developing after the coin has been slabbed. However, I do think these cases relatively uncommon. Obviously, such coins will develop problems whether you slab them or not and so slabbing cannot be blamed for the issues.

Perhaps the coin should get a good dip before slabbing

OK, thanks Gents. Info much appreciated. That confirms my suspicions.