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Green Corrosion on old Lincoln Cents
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<p>[QUOTE="cdb1950, post: 29695, member: 1735"]Sounds like something in the environment is causing these to corrode. Could be the plastic used to store them, or something else. You might want to re-holder them. If they have been stored as long as you say, there is a pretty good chance they were put in soft plastic coin holders that were popular at that time, but contained polyvinylchloride (PVC), a material that exudes corrosive gases over time as it deteriorates. This will settle on the coin surface and start to eat away the metal over time. This green gunk will continue to grow.</p><p><br /></p><p>Cleaning is a real bug-a-boo. If the plastic is the culprit, then the coins are already coated with the corrosive plastic and that will need to be 'washed' off. Use acetone to do that, a good solvent, but has little effect on the metal of the coin. It most likely won't remove the green gunk, but it will remove the bad coating so corrosion will stop. </p><p><br /></p><p>Removing the green gunk on copper coins is really tough to do without altering the toning/luster/appearance of the coin. I wouldn't do that unless it significantly detracts from the look of the coin. Most dips and cleaners will also remove any natural toning, which is bad, so you have to decide if the coin would look better with artificial toning or the green gunk. </p><p><br /></p><p>Check some of the other threads regarding cleaning coins. Lots of good advice, do's and don't's.[/QUOTE]</p><p><br /></p>
[QUOTE="cdb1950, post: 29695, member: 1735"]Sounds like something in the environment is causing these to corrode. Could be the plastic used to store them, or something else. You might want to re-holder them. If they have been stored as long as you say, there is a pretty good chance they were put in soft plastic coin holders that were popular at that time, but contained polyvinylchloride (PVC), a material that exudes corrosive gases over time as it deteriorates. This will settle on the coin surface and start to eat away the metal over time. This green gunk will continue to grow. Cleaning is a real bug-a-boo. If the plastic is the culprit, then the coins are already coated with the corrosive plastic and that will need to be 'washed' off. Use acetone to do that, a good solvent, but has little effect on the metal of the coin. It most likely won't remove the green gunk, but it will remove the bad coating so corrosion will stop. Removing the green gunk on copper coins is really tough to do without altering the toning/luster/appearance of the coin. I wouldn't do that unless it significantly detracts from the look of the coin. Most dips and cleaners will also remove any natural toning, which is bad, so you have to decide if the coin would look better with artificial toning or the green gunk. Check some of the other threads regarding cleaning coins. Lots of good advice, do's and don't's.[/QUOTE]
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Green Corrosion on old Lincoln Cents
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