Hamon disappearing act

Chiro75

Chiro75

Joined
Feb 4, 1999
Messages
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I wonder if you guys who do differential heat treats have noticed this, and what your explanation/theory is. On 1095 and 1084, at least (unforged), as I'm hand finishing my blades I noticed the hamon best at around 600 grit. Once I go to 800 and definitely to 1000, it is almost impossible to see, no matter how I tilt the blade in the light. Have you found that, too? I know there is a huge process to how traditional Japanese sword polishing is done, and the water-quenched and different forged steels make a huge difference, too, but they get such incredible hamon without etching. I've nevr had an opportunity to handle those types of blades. Do the finishes look closer to 600-ish grit handrubbed finishes, or are they highly polished and the hamon comes back at even finer grits that 1500?
 
If you really nail the clay hardening and get a martensite edge with pearlite back, you'll be able to see the hamon at any grit.... from 50x to XXXXX.

I've seen many Japanese swords, and the polish is extremely fine. I've also seen the process done (traditional polishing).

The fine stone work basically starts after what we would call a 1500X-2000X abrasive paper finish.

-Nick-

http://www.wheelerknives.com
 
I guess I CAN see it at any grit, but it's most obvious at 600, then gets harder to see from 800-1500. Just curious why that would be...
 
Like I have always done:
1) "Normalize" once (although I may be overheating it a bit according to what you said on that other post!)
2) Clay coat
3) Bring to non-magnetic
4) Quench in hot oil
5) Walk upstairs and temper at 380 for 1 hour.
 
I've had that happen to me too, though mine showed best unetched at 400 grit. The japanese waterstones work differently then sandpaper, they cut open the grain much like acid etching opens the grain. Sanding smears the grain much like, but not as bad as, buffing. Also, the polishers technique is to concentrate on the hamon itself after the main polishing with tiny little finger stones.
 
Traditional polishing stones are an entirely different beast from anything you'll find in the west, down to the structure of the stone itself. Funny thing that develops over the course of 1000 years or so of experimentation. Part of the issue may be that with what you're using, and how you're using it; you can lose the hamon and hada in a traditional blade just by buffing it.

Barring that, you may look into getting some traditional finishing stones (hazuya, not jizuya), and have a bit of a go at that. I can talk you through it if you're brave enough. ;)

Darryl
 
What about the quench? The Japanese always quench in water, not oil. I don't have much practical experience myself but this much I know that oil won't produce nearly as nice hamon as water.
 
I do find that the appearance of the hamon is also dependent on the type of backing you use. In the very high-grit final polishing phases, the Japanese method of polishing uses nothing but fingertip pressure holding the abrasive-loaded paper. The finishing pressure is much lighter. You cannot achieve this if you are using a hard backing surface on your sanding medium. You are not trying to GRIND the steel down, you want to accentuate the differences in the grain and the hardness between hard and soft.

Try this. Once the bevels are flat and you have a nice established finish, do the final steps going up through 1200, 1500, 2000grits with the wet and dry backed up by a leather scrap or a piece of rubber sheet, rather than a bar of steel or Micarta. Use softer strokes as the grit is worn out so the paper starts to burnish the steel.

I don't know if this makes any sense or will work for you, but thats what I have been doing lately to bring out hamons that are either not etched or only very very lightly etched. It will help even with hamons that are etched up also. Jason.
 
jason, currently I sand using a small wood block I wrapped with a bicycle tire inner tube (road bike, not mountain bike), so my paper is backed by a thin rubber piece and it has quite a bit of give.

Certainly, I would not expect to achieve a hamon on a stock-removed 1095 oil-quenched knife like the Japanese achieve on a traditionally polished knife of forged tamahagane! But it's be nice to get close! :D
 
Something you might consider, is the application of borax to the blade before you apply your clay coating. I heat the blade just enough to get the borax to stick to the surface, then continue to heat untill it flows over the blade surface. Let the blade cool and apply the clay. I take an artist brush, dip in water and smooth the clay at the area where the hamon will appear so there are no gaps of any kind along this line. The borax aside from stopping decarb seems to give better stick to the clay. I get a more defined hamon using this tec. Personally,
I am suspect of any steel knowing if it is being abraded by stones, sanding belts
or anyother material. What steel does understand is heat, as energy, being applied or taken away. Fred
 
Chiro, One result you will like, if you try the borax coat,is when you do the quench the borax almost shatters and is easily removed with a brass scraper. The surface of the blade is quite clean. Very nice to grind.
 
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