8620 is a 'casehardenable' modern steel, but as rk22 found, not everyone doing C/C work necessarilly gets the results desired. The primary need is hardening of the surface for wear, then the colors we like so much for the correct look. Sounds a bit silly at first, but it is possible to get the colors that look correct without hardening or with barely hardening the steel. Many tend to look for the colors and forget about the hardness needed on the parts. Some of the modern purveyors early on found this out and did most of their work in that slightly lowered temp range. Nice colors, but no wearability at all for working guns. The normal temp range to color and harden is 1430/1450F. Warming the quench up to 90F will also avoid some warpage but still get colors and hardening,,anymore and no hardening will result. 'Hard' water in the quench will generally kill the colors. Varying those elements will change the colors, hardness depth, etc. It doesn't take much to tweak the process. Bone charcoal and wood charcoal must be dryed first B4 use. Moisture in the mix will make the colors cloudy or nearly non existant. Vary the mix, and vary the colors. Time in furnace is critical. A few minutes too long and the colors will be off. Same thing with removing the 'pot' from the furnace for the quench. Everything has a sequence,,a timing that must be followed. Once the correct format it found that gives the desired results, little can be altered and still expect to get those results. Everyone has their own way of doing it and getting their results. Even with all that, many pieces are 'enhanced' after C/C with a torch with a '0' or '00' tip. Thats best done by warming the piece to around 200F first B4 drawing the colors out with the torch. Laying the pieces on top of the shut down oven was a good spot to do the warm up.
