Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Tumbling a copper coin to clean it
Q. I found an old copper coin with my metal detecter the size of a silver dollar. I wish to clean it enough where I can read the date and other important details. I have tried soaking the coin in olive oil for two weeks and have yet to remove the grit that seems to have encrusted my coin. I have a tumbler and have considered using it to clean the coin. What is the best mixture to use in the tumbling process?
Joey Warenzak- Savannah, GA, USA
2002
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A. Olive oil isn't generally thought of as a good cleaner. I would suggest using a good cleaner/degreaser like Dawn dish soap and a relatively stiff toothbrush to remove the easy crud. Then try using some lemon juice to deoxidize the surface, but by all means don't tumble the coin. Tumbling will only wear away the high points of the surface - eventually leaving a smooth (and unreadable) surface. Don't leave the coin in the lemon juice too long, or it may start eating away at the copper. Hope this helps. Dan Brewerchemical process supplier - Gurnee, Illinois A. Old trick from "Hints from Heloise" try mixture of acetic acid ⇦ this on eBay or Amazon [affil links] and sodium chloride. If you can't get your hands on that, try vinegar ⇦in bulk on eBay or Amazon [affil links] and table salt (same thing!). Nice deoxidizer for copper without harming your coin.  Milt Stevenson, Jr. Syracuse, New York 2002 |
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