How they made chisels at Nooitgedagt.

[george wilson]

Kees,you have such a remarkable grasp of English,though it is not your first language. Sodium nitrate is a correct bath to refer to. Pure sodium is a very active and dangerous metal ! It never can be used exposed to air. They used to put it inside the exhaust valves of aircraft engines as it conducts heat faster away from the head of the valve.

[Robert Norman]

Could easilly blast the daylight out of you!

Might be best to stick to O2 and some cooking oil for us backyard smiths!

[Kees Heiden]

I certainly have no intention of using these salt baths in my back yard! O1 or W1 and oil to quench. Heat up the oil a bit, stir well when quenching. Normalise the steel first, then bring it up to critical again (non magnetic point) and quench quickly. Temper immediately after quenching in the oven. That is the easiest and safest way of heat treating tool steel at home.

And thanks George. I learned a lot of English on this very forum! Best way to learn a language is using it. Now, if I also could learn to type without errors...

[Patrick Chase]

I think there is a lot a lot of confusion in this thread. Patrick talks about using "liquid sodium" after hardening. Stewie talks about salt bath quenching of steel that had been above the critical temperature. Liquid sodium is not a salt. Kees talks as if the quench medium were held at the critical temperature.

I screwed up - it's salt, not liquid Na. Confused my reactor coolants with my quenchant...

EDIT: I also wasn't careful with my wording - "after hardening" should indeed have been "after heating to critical temperature". Stewie's link is to the right thing.