Quenching color case hardening with air bubbles

[JPK]

I tried an experiment with the wire wrap idea. Two pieces of the same stock packed in the same crucible with 3:1 mix. Heat was 1400 for one hour, quenched in tap water (about 50 degrees?) that was dumped from one bucket to another just before quench. They look as much the same on all sides and not enough different to call to my eye.  From my experience ratio of charcoals, getting the dust out of it, turbulence in the clean water and the shortest drop are the most important points. Time at heat determines thickness of case and the colors stay bright for years under normal use. Bubblers seem to be another good way of getting the water stirred up in larger tanks.

[Tom Cooper]

I have to agree about the colors being a less important by-product of the hardening process, I tend to remove the colors anyway as it tends (to my eye) to be distracting in its effect.

I have tried the wire wrap and also found it inconclusive, higher temps tend to wash the colors and lower temps tend to give better results, if too low then your parts are not hard, in my limited experience.














Very first lock.

[keweenaw]

One can get as complicated as one wants on color hardening.  The link below is to David McKay Brown in Scotland whose guns sell for $40k up.  Note his simple cylindrical crucible and the high end garbage can quench tank, although I suppose in Scotland it's a dustbin.  http://www.mckaybrown.com/www.mckaybrown.com/Case_Colouring.html

I don't know what one could want in the way of colors that are better than his.
http://www.mckaybrown.com/www.mckaybrown.com/The_Side_by_Side_Gun.html

I know from experience that different steels will color quite differently.  I did two locks in the same pack.  One was 8620 and the other some unknown steel in a hand made lock.  The 8620 lock came out with vivid blues, etc., the other lock came out with the most insipid, washed out colors except for one hole that had been plugged giving a bright spot on the lock.

Tom