Author Topic: Verdigris on silver  (Read 360 times)

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Offline mrbadexample

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Verdigris on silver
« on: September 29, 2017, 04:12:41 PM »
Hi All,

I have a few pieces like this. They need help.  :'(

Where do I start please?

Thanks,
MBE

Offline THCoins

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Re: Verdigris on silver
« Reply #1 on: October 01, 2017, 03:19:31 PM »
Looks like hard deposits on fairly goog silver. I might let it rest like this.
If you want to remove the green, my first try would be with a mild acid, like diluted lemonjuice.

Anthony

Offline mrbadexample

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Re: Verdigris on silver
« Reply #2 on: October 01, 2017, 07:31:15 PM »
Thanks Anthony, yes, they are hard deposits. I don't normally clean anything, but I am concerned that this will spread if left untreated. Intervention seems appropriate in this instance.

Offline EWC

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Re: Verdigris on silver
« Reply #3 on: October 01, 2017, 07:45:55 PM »
Anthony is correct - and I see zero risk that this will spread, so nothing to worry about either way

Rob T

Offline mrbadexample

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Re: Verdigris on silver
« Reply #4 on: October 01, 2017, 11:18:53 PM »
I had assumed it would spread if left untreated. If it won't, it's less of an issue.

I have been able to mechanically chip a few flakes off but can only do this with a metal pick so the danger of scratching it is very high.

I might try boiling it to see if the thermal expansion might loosen the encrustation.

I have a few of these so I guess sacrificing one to experimentation might not be so bad.  :-\

Offline THCoins

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Re: Verdigris on silver
« Reply #5 on: October 02, 2017, 01:36:10 PM »
You can use thermal cleaning both ways. After having it in boiling water for a  few minutes just throw the coin in cold water with ice cubes.
Repeat few times. Do not use on coins with flan cracks.

Offline mrbadexample

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Re: Verdigris on silver
« Reply #6 on: October 09, 2017, 09:02:00 PM »
I am making some progress. After a few cycles of boiling / freezing I have managed to mechanically pick off some of the surface encrustation. It doesn't seem to have affected the surfaces of the coin at all, fortunately.

The problem is that the only thing I can find that is tough enough to pick off the verdigris (if that's even what it is) but delicate enough not to gouge the coin is my thumbnail. I now need a new thumbnail.  :-\

Offline THCoins

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Re: Verdigris on silver
« Reply #7 on: October 09, 2017, 09:34:25 PM »
That's already quite some improvements !
And luckily nails grow back..  :)

Offline mrbadexample

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Re: Verdigris on silver
« Reply #8 on: November 01, 2017, 12:06:19 AM »
Looks like hard deposits on fairly goog silver. I might let it rest like this.
If you want to remove the green, my first try would be with a mild acid, like diluted lemonjuice.

Anthony

Well I didn't have any lemon.   :(

But I did have a lime.  :)

The results are quite astonishing. I'll post some pictures in the morning when I've got some daylight for the photos.

Offline mrbadexample

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Re: Verdigris on silver
« Reply #9 on: November 01, 2017, 01:08:45 PM »
I confess I didn't expect anything like this:

Online Figleaf

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Re: Verdigris on silver
« Reply #10 on: November 01, 2017, 04:04:39 PM »
Excellent result, but now the colour is off. See what capnbirdseye has to say on sulphur to correct this.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline THCoins

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Re: Verdigris on silver
« Reply #11 on: November 01, 2017, 06:25:10 PM »
Spectacular result ! And very nice to see the different stages. When i experiment i always forget to make the 'before' photos because usually i consider the coin lost already. When it turns out good i have nothing to show for it.
I never used lime, but is should do about the same. I think it is more acidic than lemon, contains less ascorbic acid, and some more exotic acids like malic acid, but it turned out great.
I don's mind the white silver look. It will tone in time by itself. I usually let cleaned coins rest on an open wooden shelf for some weeks. That's usually enough for some toning to return. (But I live i a quite polluted area near an airport  :()

Offline mrbadexample

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Re: Verdigris on silver
« Reply #12 on: November 01, 2017, 08:05:44 PM »
Here's another one, equally as successful, and with no need to wreck my fingernails. Thanks for the suggestion THCoins. :)

I'm not too worried about the toning either. It'll come back.

Online Figleaf

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Re: Verdigris on silver
« Reply #13 on: November 01, 2017, 08:53:49 PM »
Indeed, toning will come back with time. The other caveat has to do with acids eating silver. Don't overdo the treatment or you will lose detail.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline mrbadexample

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Re: Verdigris on silver
« Reply #14 on: November 02, 2017, 07:24:25 PM »
I don't think that's been a problem, fortunately. If the "after" picture on the second coin looks a little less distinct, it's because it's not quite in focus.