Clay Coat the Spine?

[David Stifle]

Hi guys,

When appyling clay to a blade, should the spine be covered too, or left clean?I've read posts in the past debating thr consequences of clay coating the blade spine vs leaving it clear, but I'm still unclear as to what the end results are in each instance. And, what is the end result if you heat treat the blade edge up? Does the clay covered spine vs the left clear spine change the hamon?

Dave

 

[Karl B. Andersen]

David, an entire book could be writting on that subject.
The blade geometry plays an important part as well.
Leaving the spine covered or uncovered will also depend on whether or not you bring the FULL blade - including the spine - up to your quenching temp.
How are you heating the blade - in an oven with a full blade soak, or in a forge and just bringing the working area of the blade up to temp?
You can get a hamon with W2 and 1095 with no clay at all, and just manipulate the heat where you want it.
The variables are almost limitless.

 

[David Stifle]

Hi Karl,

I am learning how complex heat treating really is; I usually know what works, don't always know why it works. In the case of clay or no clay on the spine, I don't have a clue as to what the answer is. I will be heat treating in a forge, and will bring the entire blade up to full temp, and then doing an edge quench for a second or so before immersing the full blade. As for the blade geometry, this is a long blade at 18", oal 24" flat ground with a pronounced upswept curve.

Dave

 

[al clay]

Dave,
saw your post online and don't have advice, just a question. what kind of clay material are you using on your blades? I want to use that type of preparation before quench to make a hamon line on my knives.
thanks,
al

 

[silver_pilate]

Al, many makers us satanite refractory mixed with water for claying. I've switched to it exclusively, and it works very well. When I first tried hamons (which wasn't all that long ago), I used what I had which was Rutland's high temp furnace cement. It's a little tarry and hard to apply evenly. I ended up with some pitting here and there, and it can be tough to remove. However, the first knife I used Rutland's on came out like this (1095 steel):

One I did with satanite not too long ago came out like this (W2 steel):

Different steels, but both methods turned out good results. The satanite is easier to use. You can get some from Darrel Ellis.

--nathan