Rain my thoughts if you were a customer at my counter...
What metals have you tried and did you keep notes?
If there is no lasting improvements due to using different metals
have you tried coated strings?
My goal would be to improve the life of the strings either by string choice
or practice habits.
Currently the only practice habit I can think of would be to increase the
time that the strings are wiped down during a practice session because
we are going on the fact that there is a chemical issue that I wouldn't be
ablt to resolve. The best course of action until it is resolved is to try every
availible/known option.
Adding powders and such is just going to compound the problem by coating
the strings with unwanted coatings LOL.
I think a wet towel to wipe your hand(s) on often and one for wiping the strings (dry one)
and possible some coated strings may help prolong the playing time and save
ya a few bucks.