Differential heat treat went sideways on my last knife

Tried a clay slurry on a 1084 blade last weekend, just a thin line down the spine like the old tutorials show. Quenched in warm canola at 130 degrees and the edge came out glass hard, but I got a visible crack right at the clay line. I think I let it sit in the quench too long before tempering, maybe 10 seconds too many. Anyone else have trouble with the transition zone on thin stock around 1/8 inch? Would a slower oil or a higher temper right after have saved it, or is that just the risk with differential hardening?

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blairtaylor22d ago

Ever notice how the stuff that works on paper always gets fussy when you actually do it? That clay line might as well be a dotted line for where the steel decides to split, especially on thin stock like that. Slow oil helps sometimes, but really you're just betting against the transition zone every time.