How I temper my knife blades

[Ohio Rusty]

After doing the three thermal cycles of the blade, it is then heated again to barely magnetic and the lower half of the blade is quenched in warmed canola oil, moving the blade back and forth leaving the spine out of the oil for a bit. Once I feel the lower half of the blade is properly quenched, then I can submerge the whole blade. After pulling the blade out of the oil to cool. I wipe off the oil, give it a file test and prepare to temper.

I use a propane torch on low flame and s-l-o-w-l-y run the flame up and down the spine and occasionally near the tip. Being the tip is thinner, it would heat up faster. I watch the colors until I get to that purple changing to a straw color along the whole edge then quench the blade back in the oil to stop the process. I keep a wet rag handy as if one area seems to be heating up faster, I can touch the wet rag to that area to slow it down. Now it is time to wipe off the blade, go over the blade with 320 sand paper to remove the tempering colors. The blade ready to have a handle put on and and finish the handle.

 

[Alan]

Nice breakdown. The process looks really clean. And that blade in the pic looks incredible with those tempering colors shining through. You’ve definitely mastered the heat control.

 

[thedailygrind]

I love this process. You cycle it, quench it to achieve a non-magnetic state and then you torch temper it all while managing the color.

 

[ironDoug]

Nice write up! I’ve been thinking about trying a torch temper on my next build

have you ever compared the edge retention using this method versus doing a soak in a kitchen oven? I’m always a bit nervous about overshooting that straw color with a torch

 

[thedailygrind]

I've tried both methods, using a torch works well if you take your time, but the oven is definitely more forgiving. I typically start off with the torch for the rough parts and then finish it up in the oven if I’m concerned about going too far.