As pointed out by earlier posters, torch coloring these frames is akin to taking a nice collectable car with faded paint, spraying a couple of cans of Krylon on it and claiming you did the car and the collecting community a favor.
This “Low heat, Chemical Process”, in my opinion is nothing more than the old torch and tincture of benzene process that’s been around for decades; primarily as an amateurish attempt to fake true CCH.
What irritates me is when you imply that true CCH done by a professional who understands the process, is somehow more detrimental to the frame than this amateurish attempt to fake it.
The steel used in these old firearms is a low carbon “Case Hardenable “steel, equivalent to today’s SAE 1018 – 1020. The process of annealing, case hardening, and tempering this steel is much better understood today than it was 100 years ago.
I’ve got over a dozens of references in my shop, with all sorts of nifty charts, graphs and tables. To get this X depth of case on Y steel, Heat at X temperature for Y time and quench in Z. Reheating and or tempering at X temp for Y time will provide A/B Elastic Limit/Breaking strength etc.
Stating that we have somehow lost the ability and knowledge to properly case harden these old frames, would be like saying we no longer know how to make a wagon wheel.
The proper heat treatment is easy for those willing to do the research and understand what’s happening. The difficult part is getting the unique colors & patterns of the different manufacturers correct; that is where the “Black Magic” and or art come into play.
Mike Hunter