Expert: PAPAJACK - 4/23/2007

Question
I know that the consensus is "don't clean coins", but I have two cloth bags of coins.  Both bags were subjected to moisture and the penny bag developed a mold growth.  I tried cleaning them with dishwashing soap and this did a pretty good job. The pennies, however still have a gritty feel to them.  The nickles in the other bag, which have not been cleaned yet, have green coloration ( nickel salts). Any ideas?
Thanks

Answer
Hello Anthony,

Good idea using the detergent, but other than the distilled water cleaning and pat dry I haven’t heard of a restorative process that is cost effective.

You can try other PH natural inert solvents at your own risk like lacquer thinner, acetone etc.. Some people have said letting it soak in non corrosive oil (olive oil, gun oil etc.) wiping and washing or even chipping away  at crusty dirt with a tooth pick or orange stick.
Solutions that are too acid or basic will change the surface of the coin since copper is very reactive.
I notice on some older large cent copper coins that there is a shellac or lacquer coating on them. Possibly to preserve the finish but more likely to hide defects. I have never tried to remove it.

Only expensive coins I would send to a conservator like NCS:
http://www.ncscoin.com/

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Thank You and Good Luck

PapaJack