Hi Stan;
Where I first learned of this process was from an Ithaca service manual printed back in the early 1980's. I don't recall the exact dates nowe but they either were or recently had been importing some Perazzi guns. They gave full instructions for refinishing one of these by this method. There recommended Cold Blue was the old formula 44-40, but at the time I tried some Brownell's Oxpho & could see little if any difference. I didn't do any high dollar guns this way but tried it on a few cheap Stevens etc, mostly single barrels.
Ithaca recommended heating "Uniformly" with a propane torch until a drop of water would sizzle then daubing or painting the cold blue on with a Q-tip. With a bit of practise a rather nice finish could be produced.
As I said earlier even though a torch can be used for the heating this is not to be confused with the "Torch Coloring" process, which in my opinion is nothing short of a Crime.
