A #1 bestseller PERMA BLUE Liquid Gun Blue is the proven way to touch-up scratches and worn spots or to completely reblue 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.