Don makes a good point. Scrape the rust off of the file with whatever method you
prefer before immersing it in any acid. The rust will block the action of the
acid and create pits in the steel where the acid can attack the uncovered steel.
Much better to prevent the rust in the first place but if that was easy we would
all be doing it already.

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From: Don Schwartz<mailto:dks@t...>

No doubt it works. But vinegar is acid. It will indiscriminately attack
good metal as well as rust. Not sure that's desirable. If the files are
dull, vinegar might be the thing to do. But how will you know that
before the rust is removed? I will stick with my method of de-rusting
first, then checking the files to see if they're sharp before subjecting
them to an acid bath. No, Evaporust isn't cheap. But neither are good files!