Hey Hickok: Good Post!! Around five yrs ago I had to "deburr" a burr on a cap and ball frame which left shiney metal. Not wanting to just use cold blue in the usual manner that would result in a patch of "blue", I played around with some of Brownell's Oxpho-Blue, Dicropan T-4, and 44-40 cold blues. What I did after getting the metal to the polish I wanted and degreased (used denatured alcohol), was to lightly heat the metal using light passes with a propane torch or a hair dryer. I experimented with both the propane and hair dryer heating the metal to different degrees, then applying the cold blue with a q-tip. Alot of different color variations resulted depending on which chemical and how warm the metal was. The temp of the metal produced different results. It didn't need to be so hot that the bluing 'sizzled' upon touch, just warm enough to produce the color variations found in caseharding. I then had to lightly rub the area blued. I experimented on a piece of metal similar to the gun frame.
I've used the procedure a couple of times since for touch up. Seems to wear well except at one sharp corner of the frame, but areas such as that seem to take a 'beatin' anyway. As to which heat source and what cold blue was best---the 44-40 didn't give good reslults and I liked using the propane torch the best. Would be interesting to take a raw frame and play around with it. I like your procedure, will have to give it a shot. I like your Tru-oil trick. Will have to apply it. "High fives" to yer procedure and post!!!!!!!
"Amen" to your line at the bottom of your member info-PTL!!!