W2 and hamons - Normalizing/Grain Refinement Question...

Heikki

Well-Known Member
I'm going to heat treat some W-2 tonight, weather permitting, and plan on doing some hamons. I was wondering if having clay on the blades during the normalizing and grain refinement steps will be a problem, or should I apply the clay after I've done those steps? Will it have any negative impact?
 

Casey Brown

Well-Known Member
Apply after. The thermal cycling can sometimes cause the clay to separate from the steel due to the difference in thermal coefficient of expansion. Clay it right before you are ready to quench.
 

Casey Brown

Well-Known Member
I speak from experience on this one. The first couple that I did had the clay fall right off while I was trying to heat it up for the quench, after I normalized with it on. I remember having this exact conversation with Ed after I did that.
 

Heikki

Well-Known Member
I speak from experience on this one. The first couple that I did had the clay fall right off while I was trying to heat it up for the quench, after I normalized with it on. I remember having this exact conversation with Ed after I did that.
Thanks Casey. I’m on my last thermal cycle right now. Do you try to clean the blade at all before applying the clay? I was planning on wire brushing it a bit.
 

Casey Brown

Well-Known Member
I normalize and anneal my blades before I grind. I generally grind my blades to around 120 grit before I heat treat. I don't normalize again after grinding unless I really heat up the blade during grinding. You might be okay with wire brushing, but I would probably hit it on the grinder for a couple of passes, just to give yourself a clean surface for the clay to adhere to. You also want to let the clay completely dry before you heat treat. Otherwise, if there is any moisture in the clay, it will quickly create a steam pocket that will pop the clay right off of your knife. Again, experience on this one. Many times, I will put two layers of clay on. I will create a base layer and let it dry, and then put a second layer at a different thickness. The differences in thickness will create different effects on the hamon.
 
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