a solution thats easy to make up and cheap is a saturated salt solution with some vineger added. may take a few applications but does the trick and has been around for centuries. there's another solution but it has acid in it and i don't remember the consentration or the exact acid to use. it was called aquaregia. makeup was given to me by my former chemist boss many years ago. maybe there are some wet water chemists out there that can shed some light on the mixture.
s/v Que Pasa?