Knife Making

Step 6: Heat Treating

Harden the blade! I quenched in canola oil. There are commercially available oils specially designed for the knives, but it is pretty expensive, and a lot harder to get than canola oil. 

Also, heating the blade, and cooling it down 1000 degrees in a matter of seconds is stressful. You need to make sure your normalization is done right, and some nice luck. Otherwise your blade might crack, and you'd be at step 2. 

The oil needs to be in some kind of container that will fit your knife, and heated to around 100 degrees F. This makes the oil thinner, and thus it'll move heat away from the blade faster. Heat the blade up to 1500 degrees for the final time. Once it's there, plunge the blade into the oil. Make it so it's like you're stabbing the oil. Now, don't wave the blade sideways, because then it'll warp and bend. Instead, you have to move the blade up and down in a slicing motion to cool it down fast. If you don't, it won't be fully hard. You just need to cool the blade down, hardness doesn't matter for handles. Thus, only the blade needs to be submerged.  

Sorry, no pictures for this part, was too busy with the knife.  But just remember to keep slicing with the blade. There'll be lots of smoke. Let it stop smoking, and leave it in for awhile. Watch out! The blade is brittle right now! Once you're done with this, you need to move right on to tempering.