Author Topic: Heavily stained or worse silver  (Read 2191 times)

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Offline Andrey5

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Re: Heavily stained or worse silver
« Reply #15 on: March 21, 2017, 11:04:06 AM »
Practice can decide one way or another. The coin in this condition is worth about 10-12 euro, even if cleaned, hardly more than BV at present. Not a huge risk to try a new cleaning method.
Collecting African coins and tokens, selling more than 4500 world coins from www.avscoins.com

Offline bruce61813

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Re: Heavily stained or worse silver
« Reply #16 on: April 04, 2017, 07:06:24 PM »
It could be a mix of Silver Sulfide and Copper Oxide, as most coins have a copper content. This makes it much more difficult to breakdown and restore the surface,.

Bruce

Offline bruce61813

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Re: Heavily stained or worse silver
« Reply #17 on: October 29, 2017, 02:09:41 AM »
There are occasions when the silver oxide has combined with another metal and becomes insoluble. The only recourse that I have found, is a very careful application of electrolysis, low voltage and in a soda solution. The attached photo is a WWI German medallion. When I obtained it, the details were totally buried under a hard black crust, only the face a some of the shield were visible. The medallion is silverplate on a copper base material.


Bruce

Offline redwine

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Re: Heavily stained or worse silver
« Reply #18 on: October 29, 2017, 07:48:53 AM »
Thanks Bruce, I shall give it a go...............  ;D
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Offline bruce61813

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Re: Heavily stained or worse silver
« Reply #19 on: October 29, 2017, 05:10:56 PM »
I used 6vdc and some baking soda. Never use NaCl [table salt], it will cause burns on the coin.

Bruce