After giving the knife some additional sanding to smooth out the major scratches, I cleaned it with acetone and placed it on a piece of stainless steel foil. I am not worried too much about the bevel as I will complete the grind after heat treatment.
The foil is wrapped up to make an envelope which prevents excessive
oxidization of the blade during heat treatment. The foil I use is 304
stainless steel foil wrap from McMaster-Carr, P/N 3254K22.
I fold the long edges together and press them with a block of wood.
Then the ends are folded up.
And finally another set of folds.
And into the oven. I ramp it up and soak it at about 750°C for 10 to 15 minutes, then continue up to 1060°C for a soak of 15 to 20 minutes.
This is the blade inside the envelope fresh from the oven.
I plate quench with two copper plates. I have turned on the tempering oven and set to 200°C (400°F)
Now to open the envelope and take a look. Hopefully nothing is cracked or warped.
Once the blade is cool enough to hold, I place it into the tempering oven for two hours at 200°C.
A very simple solution is to use a countdown timer, set to 2 hours.