Case hardening?

Small items can be case hardened by plunging then into ordinary sugar. I once witnessed a small bolt being converted into a (to be used once only) tap by being heated to cherry red and then being buried in the sugar bowl. (no, it wasn't a high tensile bolt!). ray t

Hi Wally

If I remember my craft apprenticeship correctly you dunk in oil to give a basic rust inhibited surface and to blacken the part.

To case harden heat until cherry red and then dunk in carbon powder and alow to cool. This will increase the carbon content of the surface repeating will increase the depth Heat again and quench in water will give you a case of high carbon hardened steel around the original item "I believe".