PSA: Don't use motor oil for quenching - almost ruined a blade

I tried using cheap motor oil to harden a knife blade because it was handy. The smoke was insane and the blade came out with soft spots that showed up after a test grind. Has anyone else gotten bad results from cheap quenchants?

2 comments

2 Comments

foster.ruby13d ago

Yeah motor oil burns off too fast and doesn't cool evenly.

wesley87312d ago

That's a tough lesson to learn the hard way, and I feel for you. Like @foster.ruby said, motor oil burns off too fast and doesn't cool evenly, which explains those soft spots. Proper quench oil or even canola oil is safer and gives way more consistent results for hardening.