I would be very interested if you'd do a thread on your color case hardening process.
Quite by accident,when I was the toolmaker in Williamsburg museum,we had a 5 gallon brine quench. We had quenched many a part in it,many with PBC No Scale compound on them. A little bit of oil had gotten into it,too as the automatic transmission quench was right beside it. That quench eventually started giving colors just like on Colt 1873's! I wish I had brought it home!! No hardening case,of course,just gave those colors. Not bright colors,just those subtle colors like on genuine Colt 1873's.