Copper seems to react funny with all chemicals I know except VerdiChem which is not a dip and wont clean tarnish .
It depends on what you are trying to do. If you are trying to remove dirt, oil, grease you should be OK with distilled water, isopropol alcohol (70% alcohol or higher), xylene, or acetone. If you are trying to remove toning, tarnish, stains, brighten it up etc the answer is NO.