I'm currently using Brownell's Oxpho blue either the liquid or the creme. I also have some Birchwood Casey Super blue which also works well. Clean the metal with acetone to remove all contaminants, warm with a hair dryer and apply the blue. Several applications may be necessary to get a dark enough blue, rinse under hot running water and apply oil (I use Birchwood Casey Barricade which is an excellent rust preventive) to prevent after rust. Do not at any time in the process touch the metal with your hands.
Last edited by gunswizard; 05/02/23.