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 Replies: 11 / Views: 1,825 |
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Pillar of the Community
Canada
1081 Posts |
I've been working my way through ~2,000 Canadian silver coins. Mostly 25c and 50c dating from 1940-65. The coins were stored in a bag in a damp cellar- the proverbial space under the stairs - for at least a decade. They're also heavily worn - in the G6/VG8 range and, s a result, they're almost all destined for the melt heap. A few moderately interesting exceptions but very little worth saving.
Question: a very large number of the quarters have a sort go grass green colouring on them - it covers the entire surface and it comes off in acetone. Does anyone know what the chemistry is there? Silver oxidation is mostly a sulpher reaction I believe and it tends to be grey-black though some other colours are also possible..
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Pillar of the Community
Canada
1505 Posts |
Acetone will most likely come to the rescue.
It will certainly not do any damage.
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Pillar of the Community
 Canada
1081 Posts |
Yes, it's working well. I'm curious as to what the green stuff actually is though.... seems not to be oxidation of any kind given that acetone is taking it off.
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Pillar of the Community
 Canada
5584 Posts |
Was there any kind of plastic in the bag or were some in holders of some type.
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Pillar of the Community
Canada
1081 Posts |
They were in an assortment of random containers. A crown royal bag (why is there always a crown royal bag?), some old wallets, various manilla envelopes....plastic bags - all over the place.
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Pillar of the Community
710 Posts |
It sounds like PVC damage, but tough to say without pics. Acetone should clean it up nicely.
Good luck!
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Pillar of the Community
Canada
1081 Posts |
I think that's it - interesting.... looking into the chemistry.
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Pillar of the Community
United States
992 Posts |
I'd also guess PVC contamination.
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Pillar of the Community
Canada
5584 Posts |
Yes, sounds like PVC contamination and , early on, causes a soft, oily green layer that acetone easily removes with no damage to the coin .. but go easy and go slow and use just what you need ... not 48 hour soaks.
Edited by okiecoiner
09/08/2020 3:44 pm
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Pillar of the Community
Canada
1081 Posts |
Roger that and thanks. As I say, 99.99% of this stuff is straight up bullion. There's a nicely rainbow toned 1936 dollar, some George V 25c that are VG/F range and a few others that someone might want. Sadly - the 1936 dot 1c and 1911 silver dollar that I feel in my bones must exist somewhere are nowhere to be found....
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Moderator
 Canada
10456 Posts |
Remember, Canadian silver coins of that date range are 20% copper, which, is the main reactant with PVC to impart a green film.
"Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert OppenheimerContent of this post is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License. See: http://creativecommons.org/licenses...0/deed.en_USMy eBay store
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Pillar of the Community
Canada
1081 Posts |
Ah - now that makes sense. So it's the chlorine in the PVC reacting with the copper to make copper (II) chloride...which happens to be green. Thanks very much @SPP.....
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Replies: 11 / Views: 1,825 |
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Posted 09/08/2020 10:36 am
