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Kevin Kevin is offline
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Default Blueing/oil quenching of mild steel

Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot ferrous
parts into a bucket of old engine oil. This gave them a blue/black
finish and I'm pretty sure we called it "blueing".

Anyway, I've been Googling and I'm a bit confused, cos blueing seems to
be a rust-proofing process which does not involve oil and oil-quenching
is a hardening process, not a rust-proofing process.

Can anyone put me straight? I was idly thinking about DIY oil quenching
to achieve moderate rust-resistance.

Do I need to use old engine oil, or will new be good/better/safer?

ISTR we heated the parts up to a dull red before quenching. Does this
sound right?


Cheers,

Rumble

from memory quencing in engine oil adds carbon and surface hardens the
steel, old oil has more carbon and therefore hardens more, I did this as
an apprentice years ago and i seem to remember they still rusted

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Kevin R
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