A #1 bestseller, PERMA BLUE Liquid Gun Blue is the proven way to touch-up scratches and worn spots or to completely re-blue most guns. It will give a non-streaky, even blue-black finish to steel (except stainless). All parts to be blued must be thoroughly cleaned with a metal cleaner such as Birchwood Casey Cleaner-Degreaser and any rust must be removed before applying the blue.