In this discussion a woodworker remembers reading somewhere that you could make your own stain by combining rust with vinegar. He tried it, and it created an almost ebony-like stain on the walnut and oak he tested it on. He wondered what he had created in terms of a chemical.

Turns out, according to one woodworker, he made a "a dilute solution of ferric acetate (FeCOOH)." Another respondent commented that he thought he had created "a process of catalytic hydrogenation, or converting a nitro group to an amino group." Whatever the case, everyone seemed to agree the concoction was pretty safe.