Does anybody know where, in the UK, I can get a small quantity , say 2 or 3 kilos of tempering salts. Googling does not seem to throw up a likely supplier.
I am not talking case hardening here but using molten salts held at temperature to back temper a quench hardened steel. Lead can also be used but as it melts at 327C it's a bit on the high side for most tempering jobs.
The salt bath method is more controllable than the usual oxide colour method used by us amateurs.