problems making choji hamon

Knifemaker87

Knifemaker87

Joined
Jan 2, 2006
Messages
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i have been researching hamons. both what they look like and how they are produced. and a have a few questions:
1. How do you make "ashi"(sp?)? (the little lines of clay perpendicular to to blade)
2. how thin can the blade edge be if you are applying a thin layer of clay over the entire blade without risking cracking?
3. if i have extensive stock removal AFTER hardening it removes the "action" from the hamon... how do i keep the action?
4. Don Fogg (in sword making notes) mentioned that if a sword didnt have good edge retention he woud simply normalize and harden again... does this mean that he is hardering with a sharp edge? if so... can i harden with a thiner edge without cracking?
5. if i do not put clay on the back of the blade (therefore not making it curve, and slightly hardening the spine) will it put less stress on the edge, therefore lessening the possiblity of cracking therefore alowing a thinner edge befor hardening?

is there something i am missing or a step i am not doing? some premise i do not know?
wow... thats a lot...those have been weighing on my mind and as everything i have done has been through personal experience or reading.... some help would be greatly appreciated
thanks
~Chris
 
Have you emailed Don Fogg or you can also email Jesus Hernandez. They are very nice guys and are willing to help.

-Mike Sheffield
 
#1, you are already doing "ashi" lines pretty good, just lines of clay 1/8'' dia or smaller running to the edge.
#2, .040 to .050 or just under 1/16'' is what I shoot for, the thinner you go the more chance of cracking, for a water quench I would keep the edge well over 1/16"
#3, if you keep your austintizing temp low 1425f to 1450f, the hamon activity will be deep and wont grind away.
#4 Don Fogg most likely ground the sharp edge off before re-HTing, Don also uses oil for quench which is a lot less likely to crack a thin edge.
#5, yes, it will still curve some but not as much, water is a very tricky quench, cool hamons but expect to crack some blades.
Ask these same questions over on Fogg's forum and you will get lots of replies.
 
I can tell you how the Japanese smiths do this as I lived in Japan for 14 years, and some of my closest friends where swordsmiths....I spent a lot of time watching and helping them, and sometimes, under their direction, I did the tsuchi-oki (putting on the clay) and yaki-ire (quenching)...

Before the clay is applied, the blade is degreased with acetone or the like. After that, you can not touch it with your bare fingers.

The edge is always at least 1 mm thick, the clay is usually 3-4 mm thick. Of course, they use water as a quenchant. If they don't like the look of the hamon, they will maybe redo it once or twice, but that seems to be the limit. They do not sharpen the blade. If they need to redo the quench, they leave the edge at at least 1mm thickness.

I don't know how you are applying the clay, but they use two layers. A thin layer (maybe 1 mm or a bit less) is applied over the entire blade first. When that dries, a second, thicker layer is applied. The second layer is also used to determine the shape of the hamon, along with ashi, etc.

After the second coat of clay is applied, they stand the blade at the front of the forge for an hour or so to dry the clay. They give it a good shake or three to make sure the clay is well adhered.

If you use water, you will generally get a much more active hamon, though you will also crack a lot of blades as you learn...Even veteran swordsmiths in Japan crack blades on a regular basis...

The curvature is part of the process as the martensitic edge has more volume that the rest of the blade, forcing it to curve. They straighten the blade afterwards by a slight heating and hammering process....

By the way, as I understood it, the edge is under compression with a softer back. If you harden the back as well, the edge will be more, not less, prone to cracking.

Hope that is of some help...
 
so.... if in forging the broken knife's brother, i forged it with a curve.... should i "uncurve" it? i thought that i would just not apply clay to spine and have the curve "built in" so to say. or should i just let it curve more? (it would be really curved)

thanks for your information.

PS... how are ashi formed? i mean do you do it with the edge of of the palett spatula or what?
thanks
~Chris
 
Yes, make it straight and it will curve naturally when quenched....

Yes, the edge of the spatula is used to set lines of clay to make ashi. If the temperature before quenching is too high, the ashi will not form....
 
They won't form in the hamon....For example, you can apply the clay to make a choji-style hamon, but if things aren't right (hardenability of the steel, temp of the blade before quench, etc.) then you will get a notare or suguha instead of a choji. You will only get the outline at the top, not the activity inside....Hard to describe....hope you can understand...
 
i gotcha!
it has to "sink in" which means it has the be hot inside... but not so hot that it "sears" it on the outside before it can get inside.
that makes sense
thanks
~Chris
 
Very good info from Kuribo, he knows what he's talking about.

Look at #3 in my answers to your questions. If you heat the steel much higher than 1450f, your steel will harden up under the clay, as in, ashi lines don't show up in the hamon. This will also happen when deeper hardening steels (high in Mn) are used. Also multiple normalizing will refine the grain, reduce hardenability and this will increase hamon activity.
 
One other thing I forgot to mention...

After the thin base layer of clay is applied and dried, the outline of the hamon desired is placed on the blade using the edge of your spatula with the second coating of clay. After this outline is applied, the area behind it towards the mune (spine)-think of it like a dam- is "backfilled" with your clay coating from the hamon outline to the spine. You don't need much clay on the spine, just make sure it is covered. This helps in keeping the clay coating uniform in thickness as you have the "bead" placed to outline the hamon as your guide....The ashi lines are done last over the top of the preceeding coating(s).

One last thing- in Japanese sword making/collecting circles, there are "good" and "bad" hamon. The shape is very important in judging the quality of the blade and the skill of the smith. I don't have time to go into all the detail here, but I make this comment because I see a lot of knives on this forum with hamon that are, at least from a Japanese viewpoint, really "bad" from a technical and/or artistic standpoint. Not that this is the fault of the makers here-they haven't had the proper training or instruction. Just be aware that there are both "good" and "bad" hamon...

Hope none of my Japanese smith friends are reading this- they would probably give me a hard time for "giving away their secrets" ;-)
 
people who inspect money for counterfits... they dont study the counterfits they study the real thing... so i have done alot of searching for real nice japanese blades. so.. i would say i have seen quite a few "good" hamons. if you wouldnt mind looking at mine after i am done... i would appreciate it.
thanks!
~Chris
 
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