I uh ... had a little adventure with an old vise one time that I found rusting away on a horse farm.
1. Here is how it looked when I found it
2. and then how it looked after 44 hours in the de-rustifying tank. Still had to be wire-brushed but the residue fell right off.
3. Here is how it looks after being treated with Permatex Rust Treatment. I like a dark finish that still looks like iron.
Of course, it took a couple of years to get it open but that's another story, or two.:D