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 Replies: 7 / Views: 7,715 |
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Valued Member
United States
62 Posts |
I have a few pennies that have some (minor) green copper oxide (mostly King George Canadians).
Is it safe to put the coins (good ones that I want to display) in an Air-Tite or will the oxidation spread?
Is it safe to put the coins (common ones) in a coin tube or will the oxidation spread on that coin and worse on to other coins in the tube? (I suppose I could just quarantine oxidized coins into their own tube).
Should I just discard any oxidized ones and ask for replacements on birthdays and holidays :)
p.s. please don't suggest any ways of removing the oxide... I refuse to clean any coin no matter what :)
Edited by mbird
08/27/2010 8:24 pm
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Pillar of the Community
United Kingdom
2133 Posts |
It's unusual but not impossible for it to spread, it depends on lots of factors; the chemical composition of the verdigris (not always copper oxide), air conditions, storage materials, the coin composition, moisture, grease on the coin, the degree of care when handling or touching the coins, and probably other things.
I always ensure that each coin I have with verdigris is stored separately from any other coin (that is, in its own separate sealed envelope).
I agree that generally spots should not be removed, because they leave an unremovable stain which often looks worse.
I see no need to discard coins just because they have verdigris, though I would seek to replace them with a better specimen or one without verdigris, and sell or swap the verdigris one.
It's often difficult to value one with verdigris in comparison to one without.
For example, is a 1927 Canadian cent in mint condition with full lustre but three small spots of verdigris in the field on the obverse, worth more or less than a 1926 Canadian cent in XF with 25% lustre (and no verdigris) ?
Opinions, anyone ?
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Pillar of the Community
Canada
3692 Posts |
I've mostly seen it spread when they're stored improperly, for example, in a thick plastic bag.
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Bedrock of the Community
United States
19931 Posts |
The green substance is called verdigris. It is not a "copper oxide". Here is my chemical definition of verdigris: Quote:
Verdigris is a complex chemical mixture of compounds, complexes and water. The primary components are copper salts of acetate, carbonate, chloride, formate, hydroxide and sulfate. The secondary components are other metallic salts, acids (organic and mineral), atmospheric gases and water. All the components are in an ever-changing and extremely sophisticated electrochemical reaction equilibrium that is dependent on the ambient environment. As long as verdigris is supplied with feed materials (air and water)it will continue to grow. If you want to simply preserve the coin, rinse it thoroughly with a quality acetone, let it dry (just a few seconds) and immediately put it into an Air-Tite. As long as the Air-Tite is properly stored, the verdigris will be essentially dormant. Verdigris will spread from coin to coin, I call it contact verdigris. If an unaffected coin is put in direct contact with the coin that has verdigris, it will migrate to the clean coin. I posted an example somewhere on this forum....search contact verdigris. If you have light to moderate verdigris, often, the coin can be conserved using my VERDI-CARE™ product (see my sig). If you have heavy verdigris, there is no way to conserve the coin without damaging it....at which point it would be considered "cleaned". I suggest you read my thread, you should learn a lot from it: https://goccf.com/t/62434 |
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Bedrock of the Community
United States
20753 Posts |
Quote:
Should I just discard any oxidized ones and ask for replacements on birthdays and holidays :)
p.s. please don't suggest any ways of removing the oxide... I refuse to clean any coin no matter what :)
Hate to say this but you'll soon notice how many do not really read exactly what some say. For example you don't want to remove stuff on your coins. Don't blame you. If they are not very valuable, why bother. If more valuable than just daily cash, hand them to some kids and you'll usually see how even those can be appreciated. Yes you could spend a lot of money and time cleaning coins but once you get old enough, time is more important than cleaning coins. Actually that is the main reason I no longer have a garden either, pay to have my car washed and stuff like that. Time to enjoy life. |
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Valued Member
United States
450 Posts |
Sometimes if you soak the coin in Olive Oil overnight , you can remove some or all of the green stuff with a Q-tip.
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Valued Member
 United States
62 Posts |
Quote:
If you want to simply preserve the coin, rinse it thoroughly with a quality acetone, let it dry (just a few seconds) and immediately put it into an Air-Tite. But... I have read (many place on the Internet so who knows if true) that Acetone can cause color change on copper and that you should not use Acetone on copper? Edited by mbird
08/29/2010 3:06 pm
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Bedrock of the Community
United States
19931 Posts |
That's folklore. If folks had "problems" with acetone, it's their own fault. I've used acetone on perhaps thousands of copper coins with no ill effect. JustCarl has also confirmed that acetone doesn't effect copper with a lot of experiments. Also, scientifically, there's NO REASON that pure acetone will have an effect on copper.
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Replies: 7 / Views: 7,715 |
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Posted 08/27/2010 10:21 pm
