Utsuri

[Jean]

Ok guys, the subject is interesting so I am going to reopen it and will delete any stray posts.

 

George and Darcy, as stated above, I deleted what was not relevant to Utsuri in your posts.

 

I have my opinion on the subject, but NMB is not a triibune and won't be one. Keep to PM.

[Gasam]

 

you could say that it isn't "real" utsuri, but does anyone really know what utsuri is?

 

I think it looks like "real" utsuri, but admittedly I am far from the most knowledgeable person in here. It is very interesting that you were able to get that in Your blades even if by accident. Of course, there is something going on with the metal that if identified could possibly be controlled and reapplied, I am thinking.

 

Also: As far as utsuri beeing a form follows function factor, I agree we see that with weaponry a lot. But could it not also simply be seen a mark of the best smiths of the time, therefore making swords by such smiths desireable? Or just as particularly beautiful blades, and therefore commanding a Premium price? We sometimes see this in weaponry as well. Even in practical weapons, there have always been engravings etc, admittedly more so in earlier times, and much less so today...

 

And lastly: There must be a metallurgy doctorate thesis idea in this thread for some aspiring phd

[BIG]

Hi

 

an additional ARTICLE about utsuri by Mishina, page 14

 

http://www.to-ken.com/programmeArchive/ ... 201990.pdf

 

 

Best Regards

[nihonto1001]

There is a polisher, whose name I will not mention, that feels almost every blade has utsuri and it is up to the polisher to bring it out. I think he explained it as a trade off between bringing out the hada and the utsuri.

 

I think of utsuri as a by product of the tempering process, where the attributes of the tamehagane make it more (or less) prevalent. As such, the steel is almost like photographic film, while the heat is the light source, leaving its imprint.

[drjoe]

the utsuri-like effects that have appeared in my blades have seemingly formed between the border of clay application and where the hamon actually formed. so, at least in my case, I believe this occurs when temperatures run on the low side and when the rate of cooling is just slow enough that the martensitic transformation doesn't run all the way to the edge of the clay.

 

the pictures I showed were of two different types of modern monosteel (1075 and 1095) so I am less impressed by the type of steel causing this (at least in my case) and think it has more to do with temperature, quenchant, and possibly the thickness of steel.

 

my belief is that utsuri represents hardening, but not pure martensitic hardening that appears as nioi or nie.

 

although my utsuri seems to be determined by clay, it has occurred in some pieces in which I essentially did hadaka-yaki, so clay is not required and I'm not surprised that it occurs in bizen blades.

[Nihonto Chicken]

Just for grins and giggles, here are a couple of shots of my October, 1942 Yoshiharu sword showing some midare utsuri (apology for amateurish photos). Note the chu to hiro suguha hamon (nioi deki). So the variations in the utsuri in this case are not likely due to variations in the quenching clay. Nor are they likely due to variations in the steel composition as it is either muji hada or mill steel (no Showa or Seki stamp). I would guess that this utsuri example is an incidental result rather than intended by the smith, this blade being a rather modest Pacific War effort with quite wavy wartime polish (though somewhat nicely finished nakago). Anyway, FWIW:

 

[Loco Al]

Just for fun. Is this utsuri?

 

 

Alan

[bone]

Just for fun. Is this utsuri?

 

[attachment=0]3D7A2003.JPG[/attachment]

 

Alan

Hmmm, don't see anything. Beautiful hamon though.

[mywei]

Just for fun. Is this utsuri?

 

[attachment=0]3D7A2003.JPG[/attachment]

 

Alan

Hmmm, don't see anything. Beautiful hamon though.

 

Looks like bo-utsuri

[bone]

Hmmm, don't see anything. Beautiful hamon though.

Why? Dont be mean my mom is watching?

[bone]

This not my statement. Account hack?

[cabowen]

the utsuri-like effects that have appeared in my blades have seemingly formed between the border of clay application and where the hamon actually formed. so, at least in my case, I believe this occurs when temperatures run on the low side and when the rate of cooling is just slow enough that the martensitic transformation doesn't run all the way to the edge of the clay.

 

the pictures I showed were of two different types of modern monosteel (1075 and 1095) so I am less impressed by the type of steel causing this (at least in my case) and think it has more to do with temperature, quenchant, and possibly the thickness of steel.

 

my belief is that utsuri represents hardening, but not pure martensitic hardening that appears as nioi or nie.

 

although my utsuri seems to be determined by clay, it has occurred in some pieces in which I essentially did hadaka-yaki, so clay is not required and I'm not surprised that it occurs in bizen blades.

 

Joe-

 

Nice work!

 

The metallurgy of Japanese swords has been investigated by several Japanese scientists/metallurgists (Sato,Tawara, Tanimura, Inoue (has focused on quenching dynamics), et al). As you have surmised, their research indicates that utsuri, in all its forms, is basically a mix of steel microstructures (ferrite, bainite, pealite, trootsite, cementite, etc.) which form in the transition zone between the hard martensitic edge and the softer back of the blade when the blade is quenched. Its formation, as with the martensitic edge, is a result of the rate of cooling of the steel with a dependency as well on the carbon content of the steel. In other words, it is an artifact of the hardening process. Please google "t-t-t diagram" which is an isothermal transformation plot (also known as time-temperature-transformation (TTT) diagram) that illustrates the phase transformations which result in ferrous steels with temperature and time.

 

As you, and those before you have discovered, it can and does, occur by happenstance. When steel of the right carbon content cools at the correct rate/gradient, utsuri forms. It is not magic or mystery, it is ferrous metallurgy and can be predicted by the corresponding TTT diagram. While I suspect it would be a challenge due to the language barrier, I would refer you, or anyone interested in learning more about the metallurgy involved with the making of the Japanese sword, to the bible on the subject: ”日本刀の科学的研究” (A Scientific Study of the Japanese Sword), by Prof. Tawara Kuniichi, (1953) who was a metallurgist and professor at Tokyo University. It is perhaps the definitive book on the subject. There is also a very thorough and useful publication called "日本刀の秘奥" (Secrets of the Japanese Sword) by Sato in cooperation with Horii Toshihide (1927) which details the extensive research they conducted into the metallurgy of the Japanese sword. It was published as a special addition to the Nihonto Koza.

 

There are modern smiths who have reproduced utsuri regularly. Of these, perhaps Sugita san (now deceased sadly) was the most famous for his work producing vivid utsuri without the use of any clay coating. He made a solid claim that this was in fact how early Ichimonji blades were likely quenched. Sumitane san, the now deceased Ningen Kokuho was also known for his research and experimentation into the production of utsuri. He has said he could produce it at will as well.

 

To add to this utsuri discussion, rather than start a new post, I will add the following here:

 

It would seem that claiming early smiths in Bizen were aiming to produce utsuri is a bit of the tail wagging the dog. Early smiths, like those who followed, aimed to produce swords that "cut well while holding an edge, and bend without breaking". This has long been the mantra of Japanese smiths. Ask one and you will likely hear these exact words...They processed their materials to produce a sword that met these criteria. Do we think that early Soshu smiths produced blades with nie consciously, perhaps because it looked nice, or even because it made the sword function better in some way? No. Nie is an artifact of the higher quenching temperatures Soshu smiths used to produce a harder edge. Nie wasn't the goal, it was a naturally produced artifact of the process they used to reach their goal of producing a harder edge. Did early Soshu smiths consciously produce sunagashi, chikei, and other activity? No. It is an artifact of their mixing high and low carbon steels together in an effort to solve the eternal problem faced by all blade makers: how to make a blade hard enough to hold a good edge yet tough (soft) enough to not fracture. This was their solution and the production of chikei and the other activities was again, a byproduct, not the goal itself. Utsuri is nothing more than a continuation into the ji of the transition zone created by the quenching process; the goal was to harden the edge. The way it was done created a wide transition zone as a byproduct like a high temperature prequench with a high rate of heat transfer produces nie as a byproduct.

 

If you spend any time around traditional Japanese craftspeople, be they smiths, carpenters, or other, you will quickly come to realize certain common traits: they have a vary narrow comfort zone when it comes to the materials and processes they use. Ask a sayashi to make a shirasaya out of oak. Ask a swordsmith trained in the Bizen tradition to make a sword in the Yamato den. Most will politely ask to be excused. They learn their craft as a process from their teacher and tirelessly work to perfect their execution of that process. Most do not like to stray from the process, most plain and simple, will not. This practically guarantees success and consistency with a high level of repeatability. If your teacher was successful, why mess with success? Read anything on modern Japanese manufacturing and you will without a doubt read of the importance to the Japanese of "the process". Or, marry a Japanese women and hear about it on a daily basis- you will learn that there is one way to wipe a floor, hang laundry, replace the toilet paper, etc.

 

All one needs to do is to look at the very existence of the kantei process. If students didn't follow in their teacher's footsteps, if there wasn't continuity within schools, traditions, etc., it would be impossible to kantei a sword to a tradition, to a school, to a smith...

 

The importance of this deeply engrained trait is that it serves as an explanation for the question of why utsuri was seen with frequency in the early Bizen group. Student copied the process of the teacher, generation after generation. As with any transmission, data is lost over time and distance. This is one rational reason for the change seen in the type of utsuri over time. Another important factor is likely the change in materials that occurred with time. In the early period, it is thought that most smiths made their own steel through oroshigane; later, cooperative efforts were made to supply local groups with steel. Still later, steel making grew larger and more centralized with material moving greater distances. Obviously, the materials played a part in the results obtained and this movement away from smith control over their materials no doubt has an effect. Finally, we see that like other crafts, smiths were influenced by fads and fashion. We know the ascendency of the Soshu den resulted in cross-pollination and the creation of such styles as Soden Bizen. Doubtlessly these changes in the process were profound and influential as well.

 

As a caveat, I will state that there are indeed instances when utsuri was consciously a goal in the process- these being instances when later smiths tried to create work in the style of the original smiths in the tradition. While the original smiths likely just did what they did, those making efforts to reproduce their work undoubtedly consciously worked to reproduce the utsuri as well. We see this today and there is no question that it too drove the ambitions of the Ishido group in Shinto and the Masahide school in Shinshinto, for example.

[paulb]

Thank you Chris for the detailed post and information.

I don't see any contradiction in the information and text you quoted and the views previously expressed. It comes back to the combination of form following function and action and consequence that has been discussed, pulled apart and argued over time and time again.

In a crude summary and interpretation of what has been said:

1. Utsuri may have originally appeared as a bi-product of the hardening process on swords of a certain steel composition.

2. Either because it was found to enhance the blade or offered an added aesthetic dimension, or both, it became a recognised feature of particular schools work

3. By repeating the process which created the original feature with the same materials and conditions utsuri could be reproduced reasonably consistantly. Within this action utsuri goes from being an accidental bi-product to a technically created featue. i.e. if it is meant to be there and you deliberately create the conditions to achieve it it is no longer accidental.

4. experimentation in manufacture enabled variations to occur.

5. later schools did try to reproduce it for its own sake in attempting to recreate characterisitcs of earlier schools. Their difficulty in some cases may be due to the differences in later steel composition rather than defficiency of skill or technical knowhow.

[cabowen]

3. By repeating the process which created the original feature with the same materials and conditions utsuri could be reproduced reasonably consistantly. Within this action utsuri goes from being an accidental bi-product to a technically created featue. i.e. if it is meant to be there and you deliberately create the conditions to achieve it it is no longer accidental.

 

Fair summary Paul. I would suggest for the above: It goes from being an occasional by-product to a regular by-product as the process "solidifiied". By-products are by definition not intentional, i.e., without deliberate intent. It is a fine, but important distinction.

[Brian]

Unless of course they had already discovered the artistic aspect of these swords, and recognized the beauty of the hataraki there-in. In whch case they would certainly have strived to reproduce the features they could see, going hand in hand with the utilitarian aspect of the sword.

So did they polish these swords? Because this was not necessary in order to use them as weapons. It would have been necessary if they wanted to see hada and hamon and hataraki (utsuri) of course.

So which was it? Purely weapon, or recognized early as art object too? Because one of those would mean they intentionally brought forth features in the steel not needed for them to perform.

 

Brian

[paulb]

wasn't the original idea behind polishing to improve the profile and cutting ability of the blade?. The finer the polisher the less friction/resistance. The resultant beauty and activity was a side effect which was rapidly appreciated and was an indicator of the construction and composition.

I think from very early in the swords history it was recognised as more than a simple cutting weapon. This is true not only in Japan but throughout the world where swords were regarded as a representation of nobility, honour etc. This being the case it would make sense to enhance the aesthetic aspect of the surface through polishing.

[Bugyotsuji]

PaulB, quote: "I think there is little doubt that to achieve any particular feature in the blade surface depends to some extent on the raw material. However if you consider neighbouring schools such as Bizen and Bitchu, they were producing very different products with raw material originating from the same source. While ko-Bizen and ko-Aoe had many common features by the time the Fukuoka Ichimonji and chu-Aoe schools were producing the characteristics were markedly different. If the raw material was the same the differences seen must be a result of technique."

 

Now I am not an expert, but it may be possible to refine this a little more. Aoe was beside the Takahashi River which runs from Bitchu Matsuyama/Takahashi down to Tamashima. Traditionally there was trading by ship from the mouth of the Takahashi River with Osaka and the Kansai, ie Yamato/Yamashina area. I know iron was found at the foot of KinoJo Yama, west of Okayama, and there is archaeological evidence of the very oldest iron smelting in Japan, producing weapons and armour.

 

Were not their (Aoe's, Bitchu's) sources of iron very different from the Bizen iron sands of the Yoshii River, beyond the central Asahi River, thus two major rivers over to the east, which passed down through Bizen/Yoshii/Fukuoka and Saidaiji?

[paulb]

Hi Piers

you may well be right, my comment was based on a description I read some while ago and paraphrased in an article written a few years ago:

Kibi was sub-divided into 3 almost equally sized areas

by the 3 main rivers which had their sources in the Chugoku Highlands and ran in to the

Seto inland sea to the south. These rivers carried iron sand from the mountains to the

lower areas of Bizen and Bitchu, supplying the raw material not only for sword

manufacture but the production of other iron tools and implements.

Schools formed alongside these rivers, with the Fukuoka Ichimonji establishing itself on

the Asahi River, The Osafune School on the Yoshii River and the Aoe School on the

Takahashi River.

the inference from this was that from the earliest times these neighbouring provinces were fed raw material from the same source down different rivers. If raw material was being imported by sea to Bitchu then it certainly could produce a different product. I guess it depends when such imports began whether at the start or towards the end of the Aoe school's work.

[Bugyotsuji]

Good find, Paul, for which thanks. Ultimately from a common source...(?)

 

(Fukuoka Ichimonji on the Asahi River doesn't sound right though. They were on the Yoshii River, surely.)

[paulb]

sorry local geography is not my strong point I just used what I found

[cabowen]

Good find, Paul, for which thanks. Ultimately from a common source...(?)

 

(Fukuoka Ichimonji on the Asahi River doesn't sound right though. They were on the Yoshii River, surely.)

 

The type and quality of minerals can change quite substantially from even two different sides of the same river...While these rivers start in the "same" general location, the Chugoku Highlands are quite a vast area. In fact, each of these three main rivers that flow through Okayama ken have different sources....so there can be no guarantee that the satetsu in each river is identical. Nor will the steel produced from it be identical if processed in different tatara or by individual smiths as oroshigane.

 

Even if the material is identical, the end result can be dramatically different, depending on how the steel is processed. The NBTHK sponsored an experiment into the metallurgical changes of tamahagane (it was analyzed at each step as it was made into swords by 8 or so smiths). The data show conclusively that the material underwent substantially different changes as it was processed by each of the smiths into a finished sword. The final analysis of the finished swords showed that it was pretty much impossible to even guess they all started with the same material.

[John A Stuart]

Why was it so extant on swords of certain schools and seemed to become more rare as time passed and then laterly replicated? My belief is that it had little to do with how the sword was forged and what steel, given that it was within normal parameters of the steels traditionally used. All in the yakiire, the hardening process. Use of clay or not, differential hardening of the mune as well as the ha, although not to the same degree. I see similar effects when working steels where degree of heating and rate of cooling leaves banding on the stock, even soft steel will show it. I can only imagine how a high polish would accentuate it. As to being able to see utsuri on old style polished swords, what we call left in the white. I think the polish available and the subsequent burnishing would have been quite sufficient enough to see it. Even old polished shrine swords show a gloss of burnish after centuries neglected. John

[cabowen]

...My belief is that it had little to do with how the sword was forged and what steel, given that it was within normal parameters of the steels traditionally used. All in the yakiire, the hardening process.

 

Depends on what you mean by little...The parameters that need to align for it to occur vary with the carbon content of the steel, and to some extent with other alloying elements also involved. Compare the TTT diagrams for two different carbon steels and you will see that the cooling rate required to achieve the phase changes is different.

[John A Stuart]

Yes there would of course be differences in the steels, but, by parameters I mean what was available that met the criteria needed to forge a sword. Primarily carbon content and relative purity. The transformation temps and timing would have been a trial and error process that became the particular smiths formula for the hardening process and may have changed slightly given alternate sourcing. It is my thought that the method of yakiire was/is the overwhelmingly predominant reason for utsuri. Given that metallurgical analysis was fairly primitive, that would have been, for the smith, the most controllable aspect beyond the mechanical aspects of forging the sword itself, and may I say it, just slightly more important. John

[cabowen]

Yes there would of course be differences in the steels, but, by parameters I mean what was available that met the criteria needed to forge a sword. Primarily carbon content and relative purity. The transformation temps and timing would have been a trial and error process that became the particular smiths formula for the hardening process and may have changed slightly given alternate sourcing. It is my thought that the method of yakiire was/is the overwhelmingly predominant reason for utsuri. Given that metallurgical analysis was fairly primitive, that would have been, for the smith, the most controllable aspect beyond the mechanical aspects of forging the sword itself, and may I say it, just slightly more important. John

 

No argument that the quenching is what produces the phase changes, which is what utsuri is. The temps necessary to produce utsuri effects fall within a very narrow band, according to research conducted by modern smiths. The metallurgy tells us that cooling rates required to produce the phase changes are a function of the carbon content, as I mentioned. If you compare the cooling rates for say a 1045 steel compared to 1080 say, you may find that what works to produce utsuri at 1045 will not for 1080. Smiths could and do have considerable control over the carbon content. They can tell by looking at a piece of tamahagane the quality and rough carbon level. Through oroshigane processes they can reduce or add carbon to the steel to get it where they want it. Bizen blades are said to be of a lower carbon content than Soshu blades, and testing has shown this. There is no doubt that smiths were well aware of the effects of heating and forging had on the steel and while they clearly hadn't a clue about carbon they knew from experience how the processing controlled the hardness, toughness, malleability, and other physical characteristics that are a direct result of the carbon content. They adjusted these factors while forging to get the steel where they knew it would harden as they wanted it to, much like a baker might adjust the dough by feel to get it where he wants it to make the kind of crust and crumb he wishes to achieve. As with bread, it is the heating that turns dough into bread, just as the heating/quenching turns the steel into a hardened sword. The raw material must be right to end up with the desired result.

[John A Stuart]

Yes, I don't think there is any doubt about having the right dough to allow the baking to create bread. No, I am refering to how the bread was baked. Somehow the ability to create the perfect crust was lost. The shinto bakers couldn't make that perfect loaf except rarely and it was some shinshinto bakers that rediscovered or produced a similar baking method to create that perfect loaf. I don't know what this method was, but, it had to do with the baking. A few gendai smiths have their experimental baking methods, but, I am not sure if it is the same as koto bakers. To continue the analogy. John

[paulb]

Chris Bowen wrote

Even if the material is identical, the end result can be dramatically different, depending on how the steel is processed. The NBTHK sponsored an experiment into the metallurgical changes of tamahagane (it was analyzed at each step as it was made into swords by 8 or so smiths). The data show conclusively that the material underwent substantially different changes as it was processed by each of the smiths into a finished sword. The final analysis of the finished swords showed that it was pretty much impossible to even guess they all started with the same material.

 

Just to broaden the thinking and to try and see what influenced what, my understanding was that one of the major differences between koto and shinto work was the raw material. for the 5 koto traditions steel was produced locally and exhibited subtle differences, as a result of slight variations in the composition of the raw material. When during the shinto period steel manufacture became more centralised a much more uniform product was created and the variation in jigane greatly reduced. There is an argument that this is why more and more flambouyant hamon were produced as smiths tried to differentiate their work on a uniform carrier. If as you say the features of the steel are mainly the result of the smith's activity and this action can drastically change the appearance of the end result why did it become so uniform when the supply centralised?

To be clear I agree that the way the smith assembles blocks, works the steel etc will have a major effect, if not the major effect, on the end result. However I think to achieve certain features the raw material must lend itself to particular traits, some did this more easily than others. Fro example is the prevalence of nie and Yamashiro and Yamato work just a result of them working at higher temperatures or did the raw material they were working with lend itself more readily to the creation of nie than that used by Bizen smiths?

I am not sure there is a difinative answer but by asking the questions and trying to think through the naswers we might get a better understanding (especially us non metal workers!)

[george trotter]

While I initially raised the question of source material being a possible factor (I think it was me), I am also interested to know if utsuri is a "good" thing in terms of blade "quality for purpose".

Does utsuri strengthen or weaken the blade?...is it deep? ...does it survive many polishes or is it soon polished off?

I mean by this question, if high peaks weaken a blade by producing a hard brittle band almost across the blade, would utsuri not produce an overall harder blade, less able to diffuse shock?

regards,

[paulb]

Hi George

I think the traditional view goes along the lines that Bizen steel was relatively soft. Utsuri being, as mentioned above, a form of transitional phase between softer jigane and nioi was harder than the surrounding metal. therefore its presence hardened the surface. I assumed but dont know that it formed in the top levels of the jigane rather than penetrating through to the core. Therefore it would harden the surface without compromising the resilience or making the blade brittle. This opens a whole new can of worms as to why the core steel was there in the first place, to increase flexibility or to cut cost, but thats a whole different debate for another time and place.

[Alex A]

Craft of the Japanese sword. p91 Briefly in simple terms.

Utsuri occurs under very specific conditions within temperature range and metal compostition...

Yoshindo (the smith) spent 3 years trying to recreate it.

He heats the blade longitudinally in three bands, the edge 800c, the back 700-720c, and where Utsuri is created 750-760c.

He maintains the technique is heating the blade to within these strict tolerances. Any deviation will result in no Utsuri, or an uneven or irregular Utsuri.

 

My novice thoughts are that other schools may have considered it an unnecessary addition, especially throughout the Sengoku period.

Or as mentioned above, may have affected performance.