Laurel Mountain Forge Barrel Brown and Degreaser is available at Brownells. It contains a detergent that allows barehanding of parts during carding. No need to clean the parts after carding, just recoat and continue the rusting process. I have never had a problem with spotting which I attribute to the detergent. For me, it produces more of a black finish on modern alloy steels, but does give a nice blue on the typical low carbon shotgun barrel. 320 grit is plenty fine enough for the final polish.
OB
