Author Topic: What is cause of this?  (Read 152 times)

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Offline Desibot

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What is cause of this?
« on: November 04, 2019, 02:27:13 AM »
Hi guys i have question regarding this coin
What has caused this issue on it
So sort of reaction or treatment?

Regards

Online Figleaf

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Re: What is cause of this?
« Reply #1 on: November 04, 2019, 10:10:46 AM »
Perhaps it was too close to a fire. You can probably get rid of the black, but the surface will remain rough.

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

Offline Desibot

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Re: What is cause of this?
« Reply #2 on: November 04, 2019, 11:08:34 AM »
Thanks peter

I was thinking maybe something reacted with the silver
And caused this bubbling effect

Is there anything you can suggest would quickly remove the black spot.

Thanks

Online Figleaf

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Re: What is cause of this?
« Reply #3 on: November 04, 2019, 11:37:24 AM »
An acid, like lime juice. Make sure you dilute it with water, use it only on the black spot, experiment with highly diluted juice, slowly adding acid until it works. When you are happy, neutralise with running water immediately, apply some soap if you are not sure you got rid of all the acid. Dry well. This is a risky operation, but the coin looks pretty bad as it is.

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

Offline THCoins

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Re: What is cause of this?
« Reply #4 on: November 04, 2019, 01:40:31 PM »
It is not only the black part that looks not OK.
The silver part is almost certainly resilvered recently. Part of that process is first harsh chemical cleaning of the coin surface. If the resilvering does not completely cover the surface, the bare parts will show severe corrosion very quickly.

Offline Desibot

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Re: What is cause of this?
« Reply #5 on: November 04, 2019, 11:23:03 PM »
Hi Thcoin thanks for your input
The coin was extracted from a very old album the album had
Plastic folders that where filled with sticky residue


As far as i am aware the other coins had similar black staining but not that shiny

The above coin do you mean resilvered (as in coated with silver again)  ???

Thanks