Warning: That 'just quench in used motor oil' advice nearly ruined a blade

An old timer at the local meetup told me to save money and just use old drain oil for quenching my high carbon steel. He said it works perfect for 1095 and he's done it for decades. Well I tried it on a chef's knife I'd spent 8 hours forging and grinding... the blade came out with a weird mottled finish and a crack right down the middle. I lost the whole piece because the oil had water in it from sitting in a bucket for months. Turns out used oil can have all sorts of contaminants that mess up the quench. Stick with proper quenching oil or at least canola from the grocery store. Has anyone else had an old timer give them advice that just flat out failed?

2 comments

2 Comments

baker.riley12d ago

Yeah that old timer advice is always gold until it's not. Sounds like he's been quenching in some kind of mystery soup. Water in used oil is a nightmare. It's like a ticking time bomb. You get that steam explosion and crack city. I'd rather toss a blade in a bucket of sand than risk that again. Especially after 8 hours of work. Old timers forget that they got lucky sometimes.

verac4012d ago

I used to be the kind of person who'd take any old timer's word as gospel, but reading this changed my mind completely. The way you broke down the water in oil thing, with the steam explosion risk, just clicked for me. I always thought you could get away with reusing oil as long as it wasn't totally sludge, but now I see how it can go sideways fast. Honestly never even considered the sand bucket route, but it sounds a lot safer than gambling on mystery soup.