"Arfa Daily" wrote in message
...
Many years ago, my brother in law, who was a mechanical engineer /
toolmaker, gave me a bag of 'case hardening powder', which I still have.
Does anyone know what exactly this stuff is (it's white, and if the police
got hold of it, I'd probably be locked up whilst they determined just what
it was ...) and how to use it ? I got to thinking about it today, when I
was stoning the edge on a chisel ready for use tomorrow on a job. It
occurred to me that once the original factory edge has gone from a wood
chisel or plane blade or whatever, and you've resharpened it, it never
seems to last as long again as it originally did. Is this because they
harden the edge when it's made ? Is it appropriate, or even possible with
home DIY facilities, to harden the edge once it's been restored ?


You are probably overheating it if you are using a grinder to sharpen it.

Arfa