I have an older blued revolver that has some scratches and dings here and there that are still bright. I'm wondering if I "paint" larger areas with something like Birchwood Casey's Cold Blue, and then wipe it off after the requisite time, if it will have the desired effect of just blueing the areas where the blueing was damaged and basically wipe off the rest of the areas (where the good blueing still is) with no ill effect, OR if it will blotch the whole thing up unpredictably. Anyone tried this before?