Etching gold with Multi-Etch®
I originally perfected Multi-Etch® for titanium production. It’s a nonacid (pH 6.8) alternative to hydrofluoric acid. I’ve also tested it on other metals with great results.
I have used Multi-Etch® to remove broken steel drill bits trapped in titanium and gold. You can use Multi-Etch® to remove light firescale from silver, but not from gold.