Do you use the forge to heat up to critical temp or use a Kiln Oven or Molten Salt bath??
I used to use the forge and guess with the color of the steel was before I heat treated and t was always a guess and hoped it turned out with no warping and I got a hard blade... This really bugged me and drove me crazy not knowing if I was getting the best results I could. Using a propane forge for this is hard to be even in temp throughout the blade and very hard to let it soak for any amount of time. I knew I needed something different....
SO I purchased an EvenHeat Kiln so I could control the temp better and let the blade soak for the desired time. This really did help with many issues I was having before which also includes having an actual heat treating oil like Parks 50 and AAA that I mentioned in a previous article. A problem that still occurs is that the knife is exposed to oxygen and creates decarb on the blade once its quenched. With some knives its okay and wont hurt the blade you just need to finish grinding enough to get through it. If you grind to close to an edge and this occurs you it can be a problem. So I am looking at purchasing a Salt Bath.
The salt bath heat treat process involves immersing your blade into molten salts. Once immersed, the blade quickly reaches its critical temperature. The blade is then allowed to soak in this bath for the amount of time you desire. Once the soak is completed the blade is pulled for further quenching and processing. The salt bath process provides an oxygen-free environment so there's no need to wrap blades and temperature distribution around the blade is very even throughout.