SWORD POLISHING.

[bmoore1322]

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

[Grey Doffin]

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

[Ray Singer]

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

[Jacques]

Hi,

 

My question is, is the hamon embedded all the way through the metal of the sword, or just a top layer only,

 

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

[shingen]

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.

[Ray Singer]

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

 

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

[Ray Singer]

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

[Jacques]

Hi,

 

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

 

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

[cabowen]

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.

[Jacques]

Hi,

 

A well made sword will have a bright hamon that remains bright through many polishes

 

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.

[cabowen]

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....

[runagmc]

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

[Veli]

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

[bmoore1322]

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

[Jacques]

Hi,

 

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.

 

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.

[nagamaki - Franco]

Hi Brian, there is a chapter in The Craft of the Japanese Sword (which should be in your library), that offers some excellent information including very good photos and diagrams on this topic, see page 80 in particular. Another term related to this topic worth researching is ' nioi giri '. It is wise when it comes to nihonto to build complete pictures and understanding of what exactly is taking place, cause too often those little missing pieces of the puzzle have a way of returning and biting when you least expect it.

[ROKUJURO]

.....With a water quenching, martensite cannot be made at more than 1,5 mm depth. The part of hamon near hasaki until kasane reaches 3 mm thick is entirely quenched, after that the quenching is only partial on each side. Hardenability depends of many factors, such as carbon content and its homogeneity, quality of steel, quality of the forging process etc...

The cross section pictures quite clearly show that the hardening can reach into the steel more than 1,5 mm (the darker areas), as far as I have learned it is about 4 mm. These very clean steels used by Japanese smiths are able to change their molecular structure very rapidly which is the reason why they should be quenched in water. Modern industrial steels - even if they are called carbon steels - contain small amounts of alloy metals besides carbon and are likely to crack when cooled down rapidly in water, so they are quenched in oil.

 

From the technical point of view a YAKIBA will always go through the material of the blade as long as the cross section has a sufficient carbon content to be able to harden. A HAMON may change it's appearence if polished many times but as long as it is not polished away from the HA side because of age or chipping or damaged by fire or heat it will be visible.

[bmoore1322]

@ Franco

 

 

I just got off the phone with Barnes & Noble, I ordered that book , they said that book has an re-release date for next month, so I will have it next month, thanks for the heads up on another book that I will need.

 

Brian

[Jacques]

Hi,

 

The cross section pictures quite clearly show that the hardening can reach into the steel more than 1,5 mm (the darker areas),

 

Do you have the measurements of theses cross sections ? When nioiguchi is near the shinogi do you think hardening goes trough the entire blade shingane include ?

[cabowen]

That depends on the construction used and the carbon content of the shingane. Steel below a certain carbon content will not form martensite. Hagane will all be transformed to martensite so it depends on how far into the blade the hagane extends. Usually shingane is mostly in the center of the blade.

 

In any case, your original comment that the yakiba is only on the surface is simply incorrect. The habuchi may not penetrate completely through the blade on a wide hamon, depending on construction, carbon levels, and cooling rate, but the vast majority of the yakiba, in most blades made well, is through the blade.

[nagamaki - Franco]

In any case, your original comment that the yakiba is only on the surface is simply incorrect.

 

Cross section images clearly support Chris on this where you can actually see the depth of the hardening going all the way through and rising quite high on some examples.

[runagmc]

Jacques, if you read through the second link I posted earlier, he states that 1.5 mm of material was removed from the one side of the tanto. As you can see, the nioi-guchi is still very much present, although it is not as narrow and bright.

 

If anyone didn't read the 2nd Usagiya article, I would suggest reading it when you have the time. It is directly about this very subject, and very eye opening as to how much material loss from polishing can affect a sword's appearance.

[jamesicus]

Well, Brian (bmoore1322), you have certainly taken your lumps on this Board and I admire your tenacity and thirst for knowledge - that augurs well for your future as a connoisseur of Nihontô that I think you will eventually become. And continuing that thought, I highly recommend The Connoisseur's Book of Japanese Swords by Kokan Nagayama - this link will take you to the Amazon offerings that include new and used copies and also includes customer reviews. Of course, there are other vendors that might offer better prices.

 

I envision you being a young man, Brian. If you keep asking thought provoking questions similar to the one that started this thread and deflect "the slings and arrows ....." like you have so far you will do well!

[Jean]

Hi James,

 

Right, no "rub"

[Jacques]

Hi,

 

Cross section images clearly support Chris on this where you can actually see the depth of the hardening going all the way through and rising quite high on some examples.

 

Cross section is juste cross section nothing more. It only show an inifinite part of steel, it's the same when you look at water of a river or a lake that you see is only surface but not that there under surface, when you are front of a closed tunnel, you see the door not the tunnel. On the over hand, if you look at the picture 9 or 10 on this link below you will see a little triangle just above the edge, we can reasonably speculate it is the hardened part of the blade; how thick is the upper part of this triangle ? a blade has usually a wideness of around 3cm and a thickness of around 7mm at the mune. I guess it is not more than 3mm.

 

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

 

Steel below a certain carbon content will not form martensite

 

True, and which percentage please ?

 

In any case, your original comment that the yakiba is only on the surface is simply incorrect

 

Top layer was not the best term yes, but further, i precised not more than 1.5 mm depth.

[Brian]

Craft of the Japanese Sword - 20 Bucks http://www.japaneseswordbooksandtsuba.c ... -yoshihara

I regard this as the first book that any enthusiast should purchase. You need to know what goes into the making and crafting of a sword before learning about the features and intricasies. Grab it...it's a great read.

There are also numerous other copies available:

http://used.addall.com/SuperRare/submit ... store=ZVAB

 

Brian

[runagmc]

Top layer was not the best term yes, but further, i precised not more than 1.5 mm depth.

 

Which was also incorrect... apparently you still haven't read the 2nd Usagiya article I posted :?

[bmoore1322]

I was watching some Youtube video's on sword polishing, and they had some great polishers on there, but none of them answered the question I asked, I heard them all say that polishing takes away metal , and needed to know if they polish a blade too much, would the hamon eventually disappear completely.

 

I did look through some books, and did a Google on it, but could not get a good answer, and I knew that there would other collectors in here that would know the answer to my question.

 

I was thinking that is why some great polishers will look a blade over for weeks before they attempt to polish it, would it take off too much metal, has it been polished too many times, that it could destroy the blade, does it have it fatal flaws, may be that is what they were looking at also.

 

Brian

[Jacques]

Hi,

Which was also incorrect... apparently you still haven't read the 2nd Usagiya article I posted

 

Yes, they say 1.5mm steel was removed, but it is modern steel with a higher carbon content and hamon becomes less visible. What will happen if you remove 0.1 or 0.2 mm steel more ? An example is not a generality

 

Insructive but in french, maybe Jean who is fluent in english can make a synthesis.

 

http://www.otua.org/acier_outils/non_al ... _froid.htm

[bmoore1322]

Sorry, I had to be able to read this, and some really good reading.

 

Thanks for posting it.

 

 

Brian

 

 

 

 

 

First paragraph ;

 

These are the simplest since they contain only iron and carbon, other elements being present there in residual content vary according to raw materials and the method of production used.

 

A carbon content equal to acquire these steels tempering hardness as high as those of alloy steels. They differ, however, the latter by a lower hardenability, which limits their use in parts of sections relatively narrow

 

Their limited hardenability also leads to the use of energetic quenching means: pure water or salt water, and more rarely for small section parts, oil.

 

In exchange, carbon steels are easier to anneal and are softer in the annealed and consequently has a machinability and cold forming ability much better.

 

Second paragraph :

 

 

 

hardness:

 

 

The hardness of non-alloy tool steels for cold work is relatively high because it is given by the carbon content.

However, deep hardening steels is very low because this property is given by the alloying elements that are present in very small quantities.

For a given tool, there will be gifts just a few millimeters of surface film thickness of martensitic structure of a heart unprocessed lack of hardenability.

 

tenacity:

 

 

Carbon steels, after quenching in water, have a low hardening depth and a heart not hard.

The toughness is partly a function of the large volume of untempered piece that enables it to withstand some shock loads.

The tenacity of a carbon steel is also a function of grain size obtained after quenching. More grain will end it, the better the toughness.

The evolution of grain size and hardness depth as a function of austenitizing temperature is much more dispersed in steels for general use and in extra-fine steel, because of differences in levels residual elements.

Furthermore, the temperature range that is available for tempering is relatively narrow in steels for general use and because of the sensitivity of these steels to overheating phenomenon.

 

Wear resistance:

 

 

It is weak-but can be improved by increasing the carbon content (Minimum: 1%). This is one of the weakest characters of carbon steels, which may not be successfully improved by the addition of carbide-forming elements.

 

 

Third, and last paragraph :

 

 

 

Temper resistance:

 

 

Hardness of 60 HRC obtained after water quenching from 790 ° C and tempered at 200 ° C decrease very quickly as soon as it exceeds the tempering temperatures of 300 ° C (50 HRC after an income of 2 h at 350 ° C). This reduction is significant regardless of the carbon content of steel.

 

Deformation heat treatment:

Distortion due to the change in specific volume of the hardened layer of a carbon steel varies in proportion to the volume tempered and lead to the expansion.

These deformations are therefore even lower than the hardness depth will be smaller. During heat treatment, deformation most to fear are not those concerning the volume change, but change of form; these shape changes are often significant and lead, for example, arrows or curtains and that of especially since the mechanical properties of these steels heat is low.

This is what gives carbon steels reputation deform easily to treatment.

 

Shades

EN ISO 4957 in May 2000, defines six shades. These grades correspond to existing nuances in the NFA 35-590 of December 1992.

 

(For the record we will resume the match shades and field of use included in the NFA 35-590 December 1992)

 

 

Field following NFA 35-590 (1992)

 

 

Shades following

NF EN ISO 4957

(2000)

 

 

Shades following

NF A 35-590

(1992)

 

Steels for general purposes

C45U C48E4U

 

Carbon steel extra fine

C70U C70E2U

 

Carbon steel extra fine

C80U C80E2U

 

Carbon steel extra fine

C90U C90E2U

 

Carbon steel extra fine

C105U C105E2U

 

Fine carbon steels

C120U C120E2U