The Dicropan IM system requires immersing the parts in boiling water, so it's not a "cold" process, but it eliminates the need for rusting in a hot box. Once the parts are polished, I can blue a complete gun using that process in a couple of days. The best cold blue I've ever used is Brownell's "Oxpho-Blue" paste. Warm up the parts with a heat gun or a hair dryer until they're uncomfortable to touch, and blot- - - -don't wipe the Oxpho paste on. Repeat as necessary to get the desired color. After 24 hours of cure time, lightly oil the blued surface. It's great for touching up holster wear, etc. but not so great for doing a whole gun.
Jerry
