I just bought a tumbler. Cheap little one. What should I put in it to try to clean up some buffalos and wheat pennies? Some fine sand? Or will this just ruin them?
Based on the suggestions of others, I went to my local Wal-Mart and bought a couple bags of white aquarium gravel. It gets the job done, along with the aforementioned water and small amount of dish soap.
I'll second the don't overload the tumbler caution. Only fill about 1/4 full with gravel, top to 1/2 with water then add coins.