This time:  2 hours at 1640 degrees Wood Charcoal with a Barium activator.  Cool down in kiln over night.  One hour at 1430 degrees with Old Used Charcoal from Pack Annealing.  Dump in water with a bit of washing soda as a wetting agent.  Glass hard and I haven't turned it down to see how deep the case is.  David

My first concern is for hardness as to me some parts need to be hard as part of their function.  I would like to get to the point of being able to Case Harden and have them look nice also.   I will take a cut on this part to see how deep the skin goes.  Have worked on a few actions that are pretty but soft so being a old machinist  "Lipstick on a Gal that doesn't want to get her hair messed up...."  David

Steel-Pounder,
Would you have a knife that you could show us? I'd really like to see the colors of your process.

Frank

frnkeore wrote on Feb 9^th, 2018 at 12:49pm:

Frank I am sorry but I havent done any of this for a few year and the knives i put CC hardened parts on are long sold. I mat have a picture of a dagger the guard on it being my very first try at CC hardening. if I can find it I will post in a day or two.

Normal carburizing temps are 1500 - 1750 f. less than 1500 and you may get some color probably not what you at looking for. no need to worry about burning your steel at these temps in a carbon pack. I have soaked steel for As long as an hour at ~2300 f in an open gas forge with out taking any precautions and not burnt my steel. it will scale heavily at this temp if the atmosphere is not slightly carburizing but that is the extent of the problem and you will not get that hot. so don't sweat it.

Again, from my personal testing (you mileage WILL vary!)

You may want to test aeration and potentially turn off aeration at time of quench. This is for you to find the happy place for you parts, your crucible stack, your pack chemistry, etc. Aerate for a LONG time, the whole time your heat cycling, preheating, etc. Then maybe turn down or off. You must test this with samples to get the outcome your after. IN ANY CASE THE HARDNESS WILL NOT BE ALTERED, it will be as hard as it could be for the soak/quench cycle used.

I found that BIG violent bubbles make AMAZING color, but spotty. Dollops of color in large flanks of tans and straws. Electric blues, like stunning blues, but only in dollops. The bubbles explode like bombs on the char pack breaking it up, creating voids. These avoids make for pockets of unprotected material that can harden in gaseous dry environments.

Smaller bubbles, the opposite. No bubbles, I noticed more uniformity in color (total coverage) or vice versa, lack of color, depending on the rate at which the char dispersed (char stack). My parts are heavy and FALL FREE from the char pack frequently. If I had the ability to have Copious CHAR avail so that the material couldn't break free, the environment will change dramatically and Ill have to alter my aeration, quench temp, etc.
I built a test case to hold a test part. I sent a Winchester SG action into the water with violent bubbles at normal temps, 100% char contact was maintained all the way to the bottom of tank. It was completely nearly one dark color (melanism)! Same temp as If I was going after mostly straw with dollops of electric blues. This for me proved the points above, contact at quench and how intimate that is maintained is what develops color, or deletes it.

Ive tried them all, I like small bubbles and violent bubbles for the crucible I have been using.

Again those bubbles agitate and cavitate the payload of parts and char and cause char to dislodge from the material at quench. That LIMITS the intimate bond and thus limits the color formation. Its a nasty viscous circle. If you skimp on char like I do due to kiln internal dimensions and crucible shape, then you may have issues with violent bubbles disrupting the bond easier than say a 3x pack (way overpacked) where the material CANT escape from the bond with char pack at water contact. The aeration saturates the water with gases but also disturbs (if bubbling at quench in any form) the char pack contact at quench.