Best way
I have tried everything in my tumbler to get the coins as clean as possible, and I can tell you their is only one way I have found to do this the right way and to clean them to the best they be cleaned. I use rocks that I picked off the ground little and big, now here is the part that will work I promise. Go to the grocery store and buy a big box of S.O.S (steel wool) pads with the soap in it already then cut off a little piece of the steel wool (S.O.S) throw it in the tumbler withe the rocks and some water let tumble for about 1 or 2 hours, and you will be amazed how clean they come out. You can use as big as a piece as you want depending on how many times you want to go to the grocery store.