TIL I was quenching in the wrong oil for 6 years

I always used motor oil for quenching because that's what my grandpa did. Last month a guy at the local hammer-in watched me pull a blade out and said 'you know that's burning off too fast, right?' He explained that motor oil has different flash points than purpose-made quench oils. I switched to Parks 50 and the difference is night and day - way less warping and the hardness came out more even. Makes me wonder how many knives I messed up without realizing it. Anybody else stick with a bad habit that long just because that's how you were shown?

2 comments

2 Comments

irisg575h ago

Ask him what made him decide to try something different after six years instead of just sticking with what worked for his grandpa? It took some guts to question a family tradition like that, and I'm curious if there was a specific failure or just a nagging feeling something wasn't right. He's lucky that guy spoke up instead of just letting him keep going.

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theawest3h agoTop Commenter

Some guts to question a family tradition" is exactly right. I bet it was more of a slow burn than one big failure, probably he kept seeing small issues pile up and finally realized his grandpa's way wasn't working anymore. Six years is a long time to just go along with something that doesn't feel right. Do you think he ever talked to anyone else in the family about it before that guy spoke up?