+1 to that.
Some cold blues do tend to stay on better. I used some Birchwood Casey on a bolt knob, and no matter how many times I wiped it with oil, the rag would be black. The Casey blueing also produced more of a dull blackish color when compared to others. Their rust/blue remover is great though. The Brownell's Oxpho Blue passes the white glove test every time, as long as you prep like your performing surgery. And if the metal is nicely polished and oil-free, you can get some really cool irridescent blues. I've done 24" barrels with it, but no matter how well you do it, it's really only meant for touch ups. I have, however witnessed a fellow at a gun show, who(using unspecified brands) could cold blue a revolver in under an hour and produce a near-factory finish. He had it down to an art, but I haven't seen him in a while.