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How do you do your clay heat treating ?

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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 charcoal in my forge, it helps keep the heat even, I can see whats going on and I don't knock the clay off.

Jens Butler
Oakwood Forge

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Jens - I use satanite. Only done a few in 1050. If I use ashi I don't run them all the way to the edge. (maybe close - 1/8 - 3-16 from) . Mostly choji or gunome pattern with little or no ashi. If trying to get sori in a katana then I leave the spine well covered. If not (tanto for exp) then I scrape clay off top of spine. I put a thin wash on entire blade then go ahead and put 'pattern' on. Unless I in a hurry I let the clay dry overnight. Using a gas forge( 40" long). Been thinking 'bout building an electeic one. For etch I use FeC or lemon juice, or vinegar. Rub out with Flitz or Semichrome


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I've tried my own mixtures with clay and ash and/or charcoal. Didn't have much luck with that. I tried the high temp mortar in a tube from Home Depot and didn't have any luck with that. I also tried Rutland fire cement. No luck there either. I have had success with Satanite though. That gets my vote. I have some refractory called Heat Stop II that I'd like to try one of these days. Todd

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Back about 20 years ago when Bob Engnath and I started to putter around with this we hit on AP Green High Alumina I think number 36 (??) furnace cement (Bob use to work for one of the larger ceramic companies out in Glendale, California before he started with HML later "Blades and Stuff"..). Works great. Bob and I must of run through several tons of 1084, 1060 and most anything else we cold think of until it hit me that most of the swords made "in the old days" were more like 1050 than anything else...1050 works quite well and it gives a very "active" temperline....especially if you use a hot brine/soap/lye mix that Bob came up with...Most of our earlier stuff was 1084 in an oil quench and we still had cracking problems until we dropped the temp at quench and heated the oil a bit...Boy it was frustrating.

I have all our notes that we jotted down when we were doing this. Little hints and all like how to more or less control the amount of curve, how to get double lines..easy ways to put in ashi and all that...In fact i am actually sorting through these now for book 4...


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Book #4, I can't wait. Put me down for 2 copys, I cant tell you how much your books have helped me over the years.
The clay heat treating I've been doing has been on non traditional blades, like skinning knives, drop point hunters, scramasax & warncliff blades. So I've been trying to elimanate any sori or sabering effect I've been having a fair ammount of luck. One of the things I like the most about heat treating this way is that with my current low $$ shop I can get a blade much closer to done before I heat treat. That saves me tons of elbow grease :)


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What mix of ingredients did the Japanese use? It had to be fairly easy to obtain since there were no chemical houses to buy from in the 15th century. The book "Craft of the Japanese Sword" by Kapp and Yoshihara has some pics and a brief summary of the process but did not provide a detailed recipe and work instruction on how to do it. However, Yoshihara's results with temper lines are pretty amazing.

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