68Camaro wrote:Tinhorn has posted a number of times including very recently on his tumbling technique.
I put together a pretty complicated process at a time when I was selling a lot of ".950 copper bullion" on eBay. It would be impractical to replicate my system to clean just a few pounds of coins.
But if you have access to a rock tumbler or cement mixer, there are a couple steps you could take. The trick is to remove the crud without affecting the patina. First you want to remove the green gunk, then you want to kill it. Tumbling the coins will remove the gunk. Acetone is said to kill it. But then you still have the problem of drying the pennies--air-dried pennies look horrible. If you have a cement mixer, you could tumble them with corn cob hamster bedding, or ground walnut shells (also available at pet stores), or a mixture. I never tried sawdust or non-clumping kitty litter, but those might work as well.
My own process coated them with carnauba wax the same way jelly beans are coated to make them shiny:
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