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Reading an old book on metalwork, I found a fact about quenching that made me stop
I was looking through 'The Art of Blacksmithing' from 1976 and it said that in the 1800s, some smiths would quench tools in urine for a harder edge, believing the salt content helped. I had always thought that was just an old wives' tale, but the book cited several primary sources from the time. Has anyone here ever tried a historical quenching medium like that, or know if there's any real science behind it?
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mark72316d ago
Wait, hold on. The salt thing is a bit off. It wasn't really about the salt. Urine has urea in it, which breaks down into ammonia and carbon dioxide when it gets hot. That ammonia can do a neat thing at the surface of the steel, adding nitrogen to it while it's super hot. This makes a super thin, hard layer. It's more about that quick nitrogen boost than just the salt content. Old smiths saw it worked but didn't know the chemistry.
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