Cyanide is the real thing. Used to case harden parts .002-.005 thick. We used it for parts that were subject to ware. Our quenching bath was oil, not water. it gave off different colors. I have an old Home Gunsmithing Digest from 1970, that lists using charcoal and also wrapping the piece in leather and cooking it that way for good colors.
That was close to 40 years ago and I wouldn't want to be around that stuff now.

Last edited by JDW; 01/06/08 12:49 PM.
David