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 Replies: 9 / Views: 4,166 |
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Pillar of the Community
United States
920 Posts |
I have a 1976 silver proof set that I opened to update albums. Both the quarter and the half have a green oxidation spot on the obverse of the coin. Any good way to remove that?
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Bedrock of the Community
United States
20753 Posts |
Sounds like there was something in that package you opened. If it's green on Silver, that is not really common. Usually Silver turns black or blue from exposure to the elements, so to speak. Sand blasting is out of course. Same with Aqua Regia dipping.  I doubt that an Acetone bath would work but that's the best and safest method to use but only after an attempt with something milder like Warm Distilles Water in a Clean Glass container. After place on soft cotton object and blow dry with a hair dryer on warm, not hot. If the water and then the Acetone does not work, it's probably to late. |
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Pillar of the Community
 United States
920 Posts |
I've seen green oxidation spots on BU clad coins several times. On Ike and SBA $ and Roosevelt dimes. This is only a 40% siver proof coin but the only time I've noticed it on silver. Where does one buy acetone at a Home Depot type store? |
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Pillar of the Community
United States
3294 Posts |
painting aisle. Acetone is used as a paint thinner for the non-coin guys.
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Valued Member
United States
462 Posts |
Has anyone ever tried high temperature under hydrogen atmosphere? That should reverse the oxidation but it may just flake of the oxidized, now-re-reduced, silver.
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Bedrock of the Community
United States
19931 Posts |
Green is indicative of a copper based surface contaminant. Was this in mint packaging?
Carl is right, that's as far as you want to take a proof before you completely ruin it.
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Bedrock of the Community
United States
19931 Posts |
Quote:
Has anyone ever tried high temperature under hydrogen atmosphere? That should reverse the oxidation but it may just flake of the oxidized, now-re-reduced, silver.
That is a brilliant question! You are correct, hydrogen is a strong reductant. I've long suspected this is one of the tools that NCS uses. I really want to try this in the lab someday! Lincoln Cent Lover!VERDI-CARE™ INVENTOR https://verdi.care/
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Pillar of the Community
United States
920 Posts |
BadThad: The coins in question were in original mint packaging.
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Bedrock of the Community
United States
20753 Posts |
Quote:
Has anyone ever tried high temperature under hydrogen atmosphere? That should reverse the oxidation but it may just flake of the oxidized, now-re-reduced, silver.
I was just on my way to outer space, near a star so the Hydrogen in the area would be hot enough to try that. I'm presently waiting for the Enterprize to beam me up. Remember that just because something is in the orginal package does not make it air tight. Also, hopefully, no one opened and then resealed it. People do that also. Nothing is air tight and again, on a proof coin, any contamination is really noticable. Sort of like a scratch on a brank new car. The only thing people see. |
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Pillar of the Community
United States
716 Posts |
Quote:
Has anyone ever tried high temperature under hydrogen atmosphere? That should reverse the oxidation but it may just flake of the oxidized, now-re-reduced, silver.
That is a brilliant question! You are correct, hydrogen is a strong reductant. I've long suspected this is one of the tools that NCS uses. I really want to try this in the lab someday!
Can't wait to hear your lab result!
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Replies: 9 / Views: 4,166 |
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Posted 01/25/2010 3:35 pm
