Producing a Hammon

J

jawilder

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Jun 27, 2006
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I have some W1 blades I haven't hardened yet. I am going to heat them in my charcoal forge but I would also like to produce a hammon. At what stage do you clay coat the blade? before heat treat or durring the tempering?

I don't suppose you could put it on the spine of the blade during the hardening because the quench would mess up the clay... right?

Is there any way I can make the clay? Maybe somethign similar to adobe (kitty litter, sand, wood ash)?

thanks guys!
 
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You can apply furnace cement on the spine to the point you want to fully harden. Then run through the heat treat procedure for W-1(have no idea what that is)

Good luck
 
I've used Rutland's or similar high temp furnace cement with decent results, but you may get some pitting you have to grind out after heat treating.

The process of using clay to produce a hamon should be basically understood first. The clay is applied to the spine of the blade prior to hardening. Have a good clean surface for the clay to adhere to, apply it about 1/8" of an inch thick or so and don't go too far past 1/2 the width of the blade. The clay acts as an insulator. It will come up to temperature with the rest of the blade during the heating process. You have to be careful not to knock the clay off with the coal. When you quench the blade, the exposed bare steel will cool rapidly, going under the pearlite nose and hardening (forming martinsite). The clay will hold the heat, allowing the spine to cool more slowly, too slow to form martinsite. Instead, you'll get pearlite and other structures. If the clay is too thick or too close to the edge, it can bleed heat into the edge and you won't get satisfactory hardening.

So in a nutshell, you have to apply the clay prior to heating and quenching, knock the clay off prior to tempering if you want to use clay to form a hamon.

You don't have to use clay, but that's a whole seperate discussion and you have to carefully watch and know when the steel reaches critical temperatures.

--nathan
 
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A hamon (more or less - ha= edge, mon=waves ), is made by allowing a shallow hardening steel to have the exposed areas harden to martensite, and the covered areas forming pearlite. The whitish area where the two meet is the hamon. One of the better coating materials is Satanite. Many other furnace and refractory cements will do, but Satanite is probably the best.
This is how I do it.

Make a thin slurry of satanite, about like thin pancake batter. Coat the entire blade, and dry with a hair dryer.

Thicken the satanite slurry to a thick mud, about the thickness of heavy cake batter. Using a plastic knife, spread this on the blade side. Turn the blade over and repeat for the other side. Take your fingers and "wipe" both sides at the same time, to remove the mud where you want the edge to harden. ( the thin wash should stay, but it won't matter if it comes off.) Shape any desired pattern with a fingertip, wooden skewer, etc. Turn the blade over and repeat for the other side. Try and match fairly closely the waves in the clay, as you don't want one side insulated and the other bare. The spine can be covered or bare, depending on what effect you are trying for.

Thin down a little of the mud to a medium batter. Take the plastic knife, dip it in the thin clay, and tap it on the edge in such a way that it makes a thin diagonal line of clay from the coated side down to the edge. Repeat over the entire edge, spacing the lines in "X" shapes about every 1/2". These are ashi lines, and will make a more attractive hamon, and tend to help prevent cracking.

Allow the blade to dry well ( overnight) helping with a hair dryer if you like. Austenitize the entire blade at 1475-1525F for 5 minutes. Avoid overheating, but assure the entire blade is fully soaked. Quench in fast oil or brine. The way I quench W1/W2 is in 130 degree Parks #50, and I go in for a count of 1-2-3, out for 1-2-3, and back in for a count of ten. I pull the blade out , quickly wipe/scrape off any clay, and straighten immediately if there is any warp. Then back in the oil to finish cooling. After a quick check to see that all went well, I immediately temper at 400F for two hours. A second temper follows at the target temp, usually about 425-450F.

Walter Sorrel's DVD on Hamon is a great resource.
Stacy
 
One key thing is that the hamon which results from the applied clay will be influenced by the clay, but not exactly replicate it. With the clay, you are moving around heat. Youre not painting what you want the hamon to look like, but instead painting clay in a pattern so that it will push heat into the pattern you want....if that makes sense.

I always picture the hamon as a moving, fluxing line much like a thunderstorm forming between a cold and a hot front....you have a cool front from the edge going up caused by the oil coming in contact with the hot steel, and you have a hot front coming down caused by the clay insulating and retaining heat....then picture that thunderstorm being frozen in time at the exact moment the steel is quenched and drops below the hardening temp.

Im sure parts of this may not be scientifically accurate, but it helps me visualize...
 
such great responses from great makers! thank you guys for sharing your knowledge.

About straightening any warps, I assume you do that with an anvil/hammer. Wouldn't that crack the steel if it were too cold?

Is there enough time before you temper it to clean it with soapy water to get the oil off?
 
jawilder said:
such great responses from great makers! thank you guys for sharing your knowledge.

About straightening any warps, I assume you do that with an anvil/hammer. Wouldn't that crack the steel if it were too cold?

Is there enough time before you temper it to clean it with soapy water to get the oil off?
Click to expand...




NO....straight into the oven for tempering. I've had knives that I took my time getting to the oven, that popped in half sitting on the counter:eek:
 
As for straightening.... If you can catch the steel before it sets up, you can straighten it with very light taps or even gloved hands. Hold it in the quench for about an 8-10 count, then pull it out and straighten if necessary then back into the quench to cool the rest of the way down. If the blade starts to stiffen up while you're working it, stop! or you can break it.

I've heard of makers having blades spontaneously snap prior to tempering, but I've never had the misfortune. I quench, and once it's cool to quench temperature, I pull it out, wipe it dry with a rag, file test it just to make sure something didn't get screwy in the process, and then I drive home (about 10 minutes) and pop it in a preheated oven. So many times it's 30 minutes to an hour after I quench before I get it in the oven. This is fine for many high alloy blades, but 1095 and W2 may have more tendency to fail spontaneously. Don't really know.

--nathan
 
jawilder said:
such great responses from great makers! thank you guys for sharing your knowledge.

About straightening any warps, I assume you do that with an anvil/hammer. Wouldn't that crack the steel if it were too cold?

Is there enough time before you temper it to clean it with soapy water to get the oil off?
Click to expand...

I straighten with gloved hands, I'm not goin to hit a fresh quenched blade with a hammer but it can be done. You only have a couple minutes to do this.

I also clean my blades before tempering and am in no hurry to get to the oven. Never had one crack after an oil quench and I've quenched many!
 
I set the "Thwacker" on the anvil before the quench. It is a 100 year old lignum vitae mallet with a 2" round head and bronze bands. When I pull the blade out of the quench, after the 10 count, it should be about 500-600F. At that point it is still austenite. Austenite is very rubbery. You can bend it with gloved hands, or whack it as hard as you want. If you use a forging hammer, however, you may dent it and create a lot of clean up grinding. The wooden mallet does a super job. Really lay into the piece, just like you were forging it. There is absolutely no way you can break it ( unless it cracked in the quench) until it gets well below 400F. It is about 50% martensite at 300F and that is where you should stop if you haven't straightened it fully. The trick is to be fast and firm. If you fear the steel, it will beat you. I know it is a cliché, but you really have to show the steel who is boss.

A two-by-four will work in a pinch, BTW.

Stacy
 
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