lily57•1mo ago

Spent 3 years quenching in used oil before I learned my mistake

I always just grabbed whatever old motor oil was sitting around the shop. Then a buddy who does knives told me to try canola oil instead because used oil has metal particles and inconsistent viscosity that messes with hardening. Has anyone else had issues with contaminants in their quench oil?

3 comments

3 Comments

patricia2621mo ago

Three years in used oil is practically a metalworking rite of passage, just a messy one. Canola works fine until it catches fire and fills the garage with the smell of burnt popcorn. On the bright side, your next batch of knives will have a much classier failed quench.

amy_craig281mo ago

Cracked myself up reading this because I literally just set off my smoke detector last week with canola oil. lol. My garage smelled like a movie theater concession stand that exploded. Now my girlfriend refuses to go in there without a gas mask. Three years in used oil is definitely a rite of passage though, I think my first batch of knives still has some mystery goo baked into the handle from a failed quench.

phoenix_bailey1mo agoMost Upvoted

Oh give me a break with this "rite of passage" stuff. Three years in used oil isn't a badge of honor, it's just poor planning and laziness. Spend the thirty bucks on a jug of Parks 50 or even canola from last week and you'll actually get a hard quench instead of a sticky, sooty mess that leaves your garage smelling like the dumpster behind a fast food joint. The whole "mystery goo" thing isn't charming, it's a sign you're wasting steel and time. If you're going to bother making knives, do it right and use fresh oil every time. Your girlfriend's not overreacting, you're just creating a biohazard that needs a hazmat team to clean up.