I have been experimenting with cleaning clad, trying to find the best method resulting in having the coins returned to as close to the original finish as possible. I was not pleased with the dull stainless finish result from using vinegar and dish soap and the acidic action of the vinegar tended to leave a harsh finish and to strip any patina that was left on the coins. Note the photo of the two nickels. The left was tumbled in vinegar and the right in borax/ammonia.
Ammonia and dish soap took a long time and did not do a good enough job on really dirty coins. I tried adding borax powder ( borax is a non-reactive wetting agent) to the ammonia and dish soap mix along with my aquarium gravel. In my opinion, the result is fantastic. Roosevelt dimes that were so covered with a rust red coating, came out amazingly clean. ( I believe the coating is caused by galvanic action on the bi-metal coins) Coins without much use and wear came out of the tumbler looking like they had mint luster on them.
For my large tumbler which holds about a gallon of material, I have 3 lb. of gravel (Under half full). I add about a teaspoon of dawn dish soap, about a tablespoon of Borax powder, and about a teaspoon of ammonia. I tumbled the nickels, dimes and quarters mixture for about 8 hours to achieve the result. There were a few painted coins that also came clean.
One strange phenomenon that I can’t explain is that the water in the tumbler turns blue-gray. It is possible that it is copper in the water, maybe from the nickels. I will do some separate tumbling to try to figure that out.
I clean copper and zinc pennies together, but separate from clad and do not add ammonia as it will strip the patina from the coins.. I only use dish soap and the borax powder along with the gravel and coins.
See Photos for results.
Ammonia and dish soap took a long time and did not do a good enough job on really dirty coins. I tried adding borax powder ( borax is a non-reactive wetting agent) to the ammonia and dish soap mix along with my aquarium gravel. In my opinion, the result is fantastic. Roosevelt dimes that were so covered with a rust red coating, came out amazingly clean. ( I believe the coating is caused by galvanic action on the bi-metal coins) Coins without much use and wear came out of the tumbler looking like they had mint luster on them.
For my large tumbler which holds about a gallon of material, I have 3 lb. of gravel (Under half full). I add about a teaspoon of dawn dish soap, about a tablespoon of Borax powder, and about a teaspoon of ammonia. I tumbled the nickels, dimes and quarters mixture for about 8 hours to achieve the result. There were a few painted coins that also came clean.
One strange phenomenon that I can’t explain is that the water in the tumbler turns blue-gray. It is possible that it is copper in the water, maybe from the nickels. I will do some separate tumbling to try to figure that out.
I clean copper and zinc pennies together, but separate from clad and do not add ammonia as it will strip the patina from the coins.. I only use dish soap and the borax powder along with the gravel and coins.
See Photos for results.
Attachments
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Nickles vinegar (L) & ammonia (R) _1666.800.jpg70.1 KB · Views: 3,123
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Before tumbling with borax & ammonia_1669.800.jpg92.7 KB · Views: 3,081
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Tumbled coins - vinegar_1664.800.jpg62.4 KB · Views: 3,104
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tumbled coins- borax and ammonia_1673.800.jpg189.5 KB · Views: 3,184
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tumbled coins_1667.800.jpg69.6 KB · Views: 3,293
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Tumbler water_1676.800.jpg71.1 KB · Views: 3,156
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tumbled coins_1667-2.800.jpg72.7 KB · Views: 3,244