I use a rock tumbler, say 50 CLAD quarters, add lemon juice just enough to cover the coins, 2 teaspoons of table salt, and your rock stuff, I tumble them for two hours, take them outside and dump into a strainer, and give a good heavy rinse with the garden hose to remove all lemon and salt residue. All that red and brown clad comes out nice and kind of shiny, the lemon/salt thing I learned from another T-Net member some time ago. When I said fifty quarters, I'm going on the idea of 100 pennies per tumbler, so to me, 100 pennies, say 75 nickels, 100 dimes, and my 50 quarters. Having said that, do not mix nickels with any dimes or quarters, you will have some dandy looking PINK nickels, I also keep a separate batch of rock material JUST for the nickels, because of any copper trace on the rock used for clad. to keep track of that, some years ago I ordered two bags of red and one bag of blue rock (blue for nickels) to run on a dual tumbler. OK then, what NOT to do. Do NOT use the lemon juice/salt with PENNIES. NO! I did that one time of course, and I believe with the lemon/salt/copper/zinc mix, I was cooking a bomb or something, that rubber tumbler barrel about turned into a little basketball ready to explode. I learned two important words, "chemical reaction". For the pennies I use a "Magic tumble clean" powder I order from a outfit called Finch Products. It works pretty good on the pennies. Two tablespoons of it with 1/2 cup water per 100 pennies. I run them 2 to 3 hours. But for the clad, the lemon/salt works way better. And there you have it. At least the way I do it. Works for me.
