I didn't clean any of my coins for the first 35 years I detected. Mostly because I don't intentionally hunt for clad. When I did dig clad, if the bank wouldn't take it, I would usually find a car wash or pop machine that didn't seem to mind. However the past few years something has happened to the rejection mechanism at the car wash in that it won't take dirty quarters. And the bank flat out refuses to accept any "dirty" coins. So I bought a rock tumbler to clean the clad. It came with a couple packets of red "rocks", some "blue" rocks, and a big packet of "special" detergent. Not figuring it made any difference, I tossed a handful of random coins in and ran the cycle. Unfortunately, putting silver colored coins in with red rocks turns them pinkish color. So after reading the instructions, I learned the blue rocks were for silver colored coins and the red rocks are for copper. So that is what I ususally end up doing. Except for the zinc cents. I put the zinc cents in with a handful of aquarium gravel and some powder laundry detergent and they seem to do just fine.
Here is a pic of some nickels I've found....... [attachment 135370 oldnickels.jpg]
and how they looked after I cleaned them in the tumbler......[attachment 135371 tumblednickels.jpg]
For the most part, I followed the instructions and used the blue rocks. But if you look closely, you will see one of the buffalo nickels is a bit pink. (third one down on the left side) That one got tossed in with the red rocks by mistake. Some of the others are still a bit "rusty red". But I think it is because I got in a hurry. I believe if I ran them through again they would clean right up.
HH Randy