# Is there a chemical that will etch antimony but not stainless steel?

I am working with ultra high vacuum equipment made out of stainless steel that has been contaminated with a number of metals, but in particular Antimony. We'd like to do some machining of the equipment but this requires cleaning prior. The amount of contamination is only a few hundred nanometers, but needs to be removed. Is there a wet chemical etch that would selectively etch antimony (and antimonides) but not stainless steel?

I had initially considered $\ce{HNO3}$ as a possibility, but it appears without $\ce{HCl}$ or $\ce{HF}$ (which will make the solution etch Stainless) its etch rate of antimony is either slow/negligible or unreported. I'm currently trying an experiment etching a small antimony pellet, but the initial results are not promising.

Any possible solutions would be preferably easy to mix and not require overly strict ventilation. The etch will be contained and ventilated to an exhaust; however, doing it in a fume hood is not practical due to the size of the equipment. Additionally, this means that highly toxic/corrosive chemicals are undesirable (e.g. $\ce{HF}$).

• Some remarks: - Antimony and antimonides suggest that you need an oxidizing agent. - The presence of chloride ions might cause pitting corrosion to the steel. - As a model for testing you could probably use antimony deposited on a surface through a Marsh test. - I would try if NaOH/H2O2 is able to dissolve the antimony deposit (ammonium hydroxide/H2O2 won't do it). – aventurin Feb 4 '16 at 22:25