The spoon carving knife I forged this summer at summer camp has finally been heat treated and tempered. With a propane blowtorch I got it up to cherry red for a few minutes then plunged it into vegetable oil. While it didn’t temporarily catch fire, it did harden the blade. Then I treated it at 400 deg in the oven for an hour. I’m hoping for a hardness of 54-60. Other knives can’t scratch it now, and it was a bear to sharpen, so I know it is harder, but not how much. Next I’ll sand the handle to 200 grit and coat with oil, although I do kind of like the roughness for handling it.