Black belt caterpillar wrestler wrote: Perhaps related.
I had a pair of glasses that the frames were always getting verdegris and found out it was to do with a nickle allergy. I produce a chemical in my skin as a response to nickle and the chemical reacts with the nickle and corodes it.
Robin

An interesting thought. Nickel allergies to jewelry are pretty well attested; I never thought to connect that to "rusters."

If it's just a nickel allegery, though, then bronze strings ought to be safe, since bronze (either phosphor bronze or bright bronze) is nickel-free. If that is the case, then wound strings should last longer than non-wrapped strings (which will tend to be nickel steel whatever the use strings, I believe). Something to check for those who have the problem.

I wonder if there might be a problem with zinc....