Thanks to all for your responses. A couple of follow ups:

1) I noticed that Sterling has several different brands of Magic Cleaner, which one is best for cleaning chips?

2) On the suggestion of a friend, who is an engineer, I bought an inexpensive ultra-sonic jewelry cleaner, $20.00. It does not do a great job on cleaning chips, except that it will loosen dirt in the small crevices in the mold, so that it will come out much easier with a soft toothbrush.

3) I found that if you use very hot or boiling water on a chip, except perhaps if it is a Chipco or Bud Jones, it will warp very easily. Lucky it was only a $1.00 current chip. Anyone want it real cheap?