clay coating

Bailey Knives

Bailey Knives

Knifemaker / Craftsman / Service Provider
Joined
Oct 18, 2004
Messages
3,775
I am interested in doing a clay coating for a differential temper, and was wondering what kind of clay is used, and what other tips and hints anyone can give me to reduce my normal "learn by trial and error" routine.
 
Its been discussed many times before, so using the search function might get you much more than what I can offer.

But here goes. I like using clay, but I don't use the traditional method like the Japanese do. I use refractory clay as a quench resist and apply it more or less where I DON'T want hardened. In the USA, it sounds like Satanite refractory cement is whats available.

I draw on the blade on both sides identically with a marker and apply the clay in thin layers with a ice-cream stick, using a heat gun to help dry the layers on before adding more. This avoids the clay bubbling and cracking off if it is not dry before going into the forge. I ensure that there is at least 1/8th to 1/4inch thickness of clay solidly adhered to the blade before going to the forge. Many makers will suggest that you allow up to 24-48hours to ensure that the clay is properly dried on and won't fall off in the forge.

The blade will take significantly longer to heat up to the correct quenching temp due to the clay acting as an insulator. Don't worry, you will still be able to see the colour of the steel from underneath the clay - weird ... !

You can either full quench in oil or do an edge quench in oil. I don't use water as there is a major risk of cracking unless you have much more experience with it than I do. Remember to leave the blade in the quenchant medium longer than you usually do, as the area under the clay will retain heat for a long time.

Many minor factors will make a difference to how the hamon turns out. That will be for you to learn with experimentation.

The blade afterwards will develop significant markings from the clay and quench which don't necessarily represent what is going on deeper in the steel. There will be lines and zones that LOOK like the hamon area but it isn't. You need to do some regrinding after the quench to clean up all the scaled / decarburised surface and etch lightly to check out whats going on.

The late, great Bob Engnath had some valuable ideas on his ways to do the clay - http://www.engnath.com Most of my ideas were adapted from his instructions on this site.

Hope this helps. Jason.
 
Thanks for the info, I should have tried the search first, but didnt. That will give me enough to go on for quite a while.
 
Popsicle sticks...

Tell me that you have popsicles in the Dakotas....

They can generally be found in the hobby shops and craft stores as mixing sticks. Thin wood stick rounded on both ends.....

Doc
 
I use furnace/fireplace cement available at Lowe's for a few bucks. Works for me!
 
you can get unused popcicle sticks in the craft dept. at Walmart also. and i like the unused ones better than the used ones, not as sticky :D
 
hey just my .02 i tried a product called rutland furnace cement. its more of gooey nasty stuff than an actual cement. it has the consistency of epoxy or Jb weld. it works really well and no drying time is needed. here's a pic of a blade I Hted with it.
the blade is 5160, just an old piece laying around Ig's shop that someone never finished. http://photobucket.com/albums/v212/MichaelSpangler/?action=view&current=Picture.jpg

first try at a clay coating, the result were good, the only flaw was in my part, i shoud have payed more attention to how i layed out the pattern
 
Hey Michael, that isn't at all a bad hamon on 5160. I usually can't get 5160 and the other deeper hardening steels to manifest a hamon as good as that.

The bubbling effect you get when Satanite is heated before its fully dried, is not really such a problem. If you concentrate on getting the very first thin layer adhered to the blade, thats all that matters. The "bubble" itself is as good as anything at being a quench resist as long as there is a thin layer of clay already stuck to the blade underneath. For that very reason, I also only grind my blades up to 80grit before applying the clay. I have taken the blades to 240grit in the past, and the clay had greater difficulty sticking on.

Also, when you quench, the blade undergoes some natural warpage as the spine contracts for longer as it cools slowly. The clay can fall off during this slow process, but don't worry - the selective hardening has already happened.

Cheers. Jason.
 
ddavelarsen said:
And how do you folks get the satanite off the blade before tempering - or do you?
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Most of it falls off in the quench.
I was patching the floor of my forge with the furnace cement and kitty litter. I got to try this comb on a blade just for the hell of it????? :confused:
 
yeah the cement puffs up, its pretty easy to get off.
thanks Jason, give he rutland cement a try and see how it works for you
 
I just did some heat treating yesterday and used clay. Like IG said most of it falls off in the quench. I lose a little in the quench. Seems like most the times I'm in a big rush but I took some time yesterday before putting on the clay. I wrapped the blades with steel wire so the clay would have something to stick to. I should find out later today how well it worked. Nice thing about the wire is after the quench you just pull the end. Kind of like opening up a roll of Lifesavers.
 
Raymond Richard said:
I just did some heat treating yesterday and used clay. Like IG said most of it falls off in the quench. I lose a little in the quench. Seems like most the times I'm in a big rush but I took some time yesterday before putting on the clay. I wrapped the blades with steel wire so the clay would have something to stick to. I should find out later today how well it worked. Nice thing about the wire is after the quench you just pull the end. Kind of like opening up a roll of Lifesavers.
Click to expand...
Ray; Thats a cool idea. Did you think that up on your own???
:cool: :cool:
 
IG, Think I borrowed that idea but can't remember forsure. I took one of the blades down to 320 grit this morning and did a few etches but I'm not seeing much yet. I think I'm going to have to warm up the etchent. It doesn't seem to work very well when its 34 degrees.
 
Bob Engath's tutorial recommends wrapping the blades with wire. Most of my clay falls off in the quench, too, but I prefer that. Makes clean up easy and it doesn't seem to affect anything negatively.
 
Always slow off the blocks, I was all set to say Hey, wire it on! but everyone beat me to it. I couldn't remember where I'd read it, thanks Michael.
 
ddavelarsen said:
Always slow off the blocks, I was all set to say Hey, wire it on! but everyone beat me to it. I couldn't remember where I'd read it, thanks Michael.
Click to expand...
Dave: You get any slower, you would be going backwards.
:p :D
 
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