if im gonna edge quench an O1 blade...

[SkaerE]

do i need to heat the entire blade to critical before edge quench?

can i just get the blade up to critical then quench it (it seems that the back of the blade and the tang wont harden anyhow)

am i wrong in thinking that the entire blade doesnt have to reach critical?

 

[Disco Stu]

It's fine if you only bring the edge up to critical. In fact I got a nice hamon (unintentional) on my first O1 blade like this.