Heat Treating Knives, Blades etc

The title pretty much says it all. I've seen the term used a lot, and I think I understand visually what part it is, but what's it from? What's it for? What's the propper definition?

I Just posted this in the Alchemy and Formulas section. http://www.iforgeiron.com/forum/showthread.php?p=7930#post7930 And I thought it would be nice to start a conversation about clay heat treating over here. What Kind of clay do you use, and what kinds have you tried ? I have just started using Satanite but haven't polished any of the blades yet ( I just did 'em last night ) so I don't know what I'll find but I'll post pics as they polish out. I wonder if it will be any different than using my home cooked mix? What sort of set up do you use for heating the blade? your coal/ charcoal forge or a gasser ? I use a steel pipe embeded in a pile of …

This is a little 1084 blade I did some polishing on today, interesting details in the hamon. I can't wait to finish it. Jens

Hello. I am almost done with a small knife in 1095, and wish to do an oil quench on it. What oil should I use? Thanks, Archie