Cleaning some brake calipers and a few other bits I had a sudden flashback. When I was in school, one of the Design Technology Teachers had an acid bath for cleaning down old metal, and used it to clean an old set of calipers for a vintage bike he was restoring. Does anyone know which chemicals/what voltage are involved? or where I can find a guide online or in a book?

The teacher is probably gone by now, and it probably breaks health and safety too.

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