Clay Tempering

P

PaceSetter

Joined
Sep 3, 2004
Messages
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I am curious to know if someone here is familiar with the tempering process using clay. If so, I would like to know if there is a certain type of clay that needs to be used, at which point in the heating process the clay need be administered, and is the clay placed on the back of the blade, or on the edge. From reading articles on this, those rare ones that I could actually find, I found the the clay is placed on the edge. However, I have also read reports that state the clay is placed on the back of the blade. Any information on this topic is much appreciated.
 
Yo Pace,

Before somebody jumps on you :) it's not clay 'tempering'. Some people are real picky on that term. I'm reading another book on Japanese swords from the 70's. They use that term and drives me to distraction. However, it is commonly used.

In any case here's a great description: http://www.engnath.com/public/manframe.htm Click on the 'Clay' link.

Steve

PS Welcome to the forums!
 
Yes I get picky about proper terms ! It's differential hardening with clay.They have info on www.swordforum.com if you search that site. Read as much as you can.It's the typical learning process But the terms are important to understand so you and anyone you talk to are both on the same track. Welcome !
 
Thank you Steve. I just finished reading the link that you sent me. My apologies to any who are, or will be offended by my terminology. I am not officially making swords or knives yet. I will be. I am just gathering what information I will need first before I take the plunge into my much anticipated hobby. Thank you again.

Pace
 
As far as clay goes everybody seems to have their own formula, as long as it adhears to the blade and it is of suficitiant thickness (3/8ths to 1/2 inch) and it is cured be for you place it in the heat it should be fine/ or you could play it safe and use santinite. normilize the blade a couple of times before coating the blade, make a solution of brine(solar salt works well) leave the blade in the heat a little longer after you think its ready because the steel needs to get to temp. at the clay. quench it edge first which will also cause a natural curve, if you what the blade to be straighter quench the spine first. hold it there until the boiling stops and hope for the best, if it goes ping well atleast you got some practice, leave the blade edge at least .040 thick prior to heat treat. hope this helps



APPLEBY KNIVES

r.appleby@juno.com
 
Mete, Yeah I think it was that marred me for life :)

After reading my metallurgy materials and understanding better what tempering is, this 70's book I'm reading really does drive me crazy. I can't make it thru a page without cringing over 'clay tempering' and 'temper line'.

The book is a translation and the author probably doesn't know how to translate the terms.

PasetSetter: no need to apologize. That is a common term and nobody is gonna get their shorts in a bind when a new member stops by - no matter what words they use. Now if you try and tell mete that the proper term is claytempering ....... :) :)

From the sounds of things, you want to jump right into the big stuff! Bully for you. Go for broke!

Steve
 
Sando said:
Before somebody jumps on you :) it's not clay 'tempering'.
Click to expand...


Oops! You know, I even know better, and I just realized that I've used that term in a post in the Knifemaking Supplies section! I tried to change it, but it doesn't seem to want to let me change the subject line.... Anyway, sorry, I should be more careful myself in using the correct terminology, I'm pretty picky about those things too and here I go doing it too...

:)

-Darren
 
Here is something else for you to think about while you are reading and studying. If you are interested in the clay coating technique of heat treating, as the Japanese do it, they (the Japanese) traditionally use shallow hardening steels and quench in water, the blade is forged straight but comes out of the quench with the gradeful curve (sori) we all know in most (but ot all) Japanese blades. So the curve is induced by the quench. This is important because if what you want to do is Japanese style with lots of activity in the hamon then you will need to find a shallow hardening steel to use such as 1050 or 1060 or 1095.

Most modern factory produced steels have alloying elements, such as manganese, added to them to allow them to harden reliably and deeply in industrial situations. These steels are generally quenched in oil since a water quench causes too much of a shock to them and will often crack. These steels can be quenched in water but the risk is high. Now if you decide to do the Japanese style blade with a modern steel, with a clay coating, and quench in oil to be on the safe side, then what often happens on longer blades is a reversed curve, a curve downward toward the edge! Modern deep hardening steels also will not produce the depth and level of activity in the hamon, which is one of the nice by-products of the clay quench.

I know it seems a bit confusing but these are all elements, among others to keep in consideration.
 
Pacesetter,
I've been selectively hardening blades useing clay for a time. Personally I like a 50-50 mix of potters clay & refractory cement cut with water to the mix you prefere. The clay process takes a little more time than other hardening techniques but what it adds to the blade is substantial. Because the clay that coats the spine does not alloy this part of the blade to cool quick enough to harden it does come thru the soft steel structures quickly and will impart a very tough yet flexible spine. This gives you the opportunity to grind a thin yet very tough blade. This is a nice feature when trying to produce that thin flexable fillet knife.
Fred :D
 
Fred.Rowe said:
Pacesetter,
This is a nice feature when trying to produce that thin flexable fillet knife.
Fred :D
Click to expand...


Cool beans, great idea.

Steve
 
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