Okay, I have seen before and after pics of some really bad blades, rusted, pitted, no hamon, or hada present, but when I see the same blade in new full polish, there is beautiful hada, hamon, I would think since polishing is actually removing small layers of metal.

My question is, is the hamon embedded all the way through the metal of the sword, or just a top layer only, like the hada is part of the entire metal make up of the sword.

I was wondering when they do a full polish is there a chance that the hamon could be polished away.

I hope I did not confuse anyone, but this has really been bugging me, I'm reading the books, and looking up online, and cannot find the answer.

thanks
Brian

Brian,
On most swords there is a skin steel and a core steel. With repeated polishing the skin is worn away and the core starts to show through. The hada will last till you get to core steel and then disappear, but it can also become degraded as you approach the core (hidden defects are brought to the surface).
The hamon doesn't stop at any one place; my guess is that at some point it starts to become weak and less interesting but that isn't necessarily at the junction between skin and core.
Grey

Hi Brian, I believe that there have been a few past discussions here where examples of nihonto cross sections were shown. Use the search feature. You can also do a google image search for "nihonto cross section". You will see in the photos how the yakiba continues uninterrupted across the interior of the sword at the ha.

- Ray

Hi,



Only a top layer. when a sword has many polishes the hamon can become less visible (ha shizumu) even disapear in some places.

Agree with Jacques, on really tired swords (polished many times through hundreds of years) it is clearly visible that the hamon is either gone or almost gone, perhaps not all tired blades but I have seen a few where the hamon is practicably gone. Also when a sword get's burned the hamon can vanish.

This will vary from one sword to the next. I used to own a Heian jidai ko-Senjuin blade in which the hamon was only a remnant in some places, just 1-2mm wide. Even in those areas, the hamon remained absolutely brilliant. I have also handled a Rai Kunitoshi tanto which, although significantly polished down and having a only parts of the hamon remaining, still exhibited a very bright and clearly defined yakiba. On other swords yes, the hamon may deteriorate as it is further polished down. There is also a school of thought that some of the characteristics that we value in koto work, such as a wide nioi-guchi and thick ashi may actually be revealed after the sword has been polished several times and werenot present in their first polish.

Hope Ted will forgive my linking to his page. These are the cross sections I was referring to earlier,,,

http://legacyswords.com/nihontoCS/crosssections.htm

One of my favorite 'nihonto stories' is about the buried Kiyomaro tanto. When it was exhumed from the ground, the sword was significantly corroded and in basically relic condition. After a great deal of material was polished away, a beautiful tanto emerged. This was the same tanto that sold a few years ago on Aoi Art in the neighborhood of 90k. The Nihonto Koza talks about this and compares the Kiyomaro with another sword which was buried, recovered and restored. The second example did not fare nearly as well, so again how well a sword sustains polish over its lifetime is case-by-case.

- Ray

Hi,



Off topic, this has nothing related with the depth of quenching.

Cross sections showing the through hardening of the yakiba have everything to do with the issue of whether or not the hamon can be "polished off", the op's initial question. In a properly hardened blade, the only way the hamon can be "polished off" is if the edge of the blade itself is removed past the habuchi.

The hamon is simply martensitic steel. When properly hardened, the entire edge, as shown in the cross sections, is martensite. This is readily visible and verified both by inspection and by hardness testing.

A well made sword will have a bright hamon that remains bright through many polishes. A sword can have "ha-shizumu", sleepy hamon, from the time it was made. This is simply a poorly done hamon, and doesn't have anything to do with the number of polishes. On older swords, that have been polished many times, it is likely the hamon was poorly done from the start and perhaps the blade was not properly hardened with regards to evenness and/or depth. Other possibilities are that the blade had chip damage and through polishing, the hamon was lost in places, or the blade was exposed to heat at some point and the yakiba was drawn out.

The famous story about the Kiyomaro tanto illustrates this well. A properly made blade can be polished down to almost nothing and as long as a portion of the original edge remains, there will be a hamon.

Hi,



I fully desagree with that I've a friend who had a shinshinto tanto with deep rust polished. the polisher removed all the rust and it turned that most of the hamon has gone away excepted on one inch on the boshi where the blade was less rusted. My friend is a metallurgist specialized in quenched steel and cementation. He was aware of the risk but he wanted to know how depth is a nioiguchi.

I will see him soon and i will take pictures of this tanto.

Perhaps then your friend's tanto was poorly quenched or had been heated at some point. As I have said, and as you can readily see for yourself in the micrographs linked above, in a properly quenched blade, the edge is solid martensite completely through. There is no way to polish it off....

From what I've seen, the answer is somewhere in between - and it depends on the sword. There may be nie and other activities that fade as layers of material are polished off the blade, but I think it would be rare for the hamon to become entirely lost, and for this to happen a sword would probably have to have been poorly hardened from the start.

Check these links, http://www.ksky.ne.jp./~sumie99/repolishing.html
http://www.ksky.ne.jp./~sumie99/effectofyakiire.html

I agree with Adam, I think the hamon of a tired sword often loses detail and brightness, but this depends on the workmanship. Martensite forms when the cooling is rapid; the cooling rate inside the steel is a complex thing to estimate if the protective clay on the blade surface has fine detail.

Veli

Okay, and thanks for all of the great answers, much appreciated.

I think I have my answer, when a polish is done on the blade, small minute layers of steel is removed, and the Hamon is still present, as it does penetrate through the metal into several layers of the steel.


Brian

Hi,



Man must consider that is a physical and chimical matter. With a water quenching, martensite cannot be made at more than 1,5 mm depth. The part of hamon near hasaki until kasane reaches 3mm thick is entirely quenched, After that the quenching is only partial on each side. Hardenability depends of many factors, such carbon content and its homogeneity, quality of steel, quality of the forging process etc... A nioiguchi can be effaced by many polishing, you have a great example with the Dojigiri by Yasutsuna, boshi on it is now invisible.