Creating utsuri

[Gakusee]

Jifu on Masatsune 

[Rayhan]

Thanks for chiming in all! @Gakusee allow me to correct my terminology, when I say low quality steel i simply meant the initial raw material from the furnace/tatara before it is put through the refining stages of manufacture. It is low quality in this context only and not as a whole. I am sorry, i know that Bizen blades are some of the finest and I have a deep love for them as well. 

 

@Jacques awesome list and thank you for this. It is most helpful for looking at which schools produced utsuri and their relevant locations across Japan and in what eras. Most appreciated. 

 

 

 

 

 

[CSM101]

Rai Kunimitsu - Nie utsuri

 

 

[Brano]

9 hours ago, Gakusee said:

Brano: by the way jifu utsuri is not about nie vs nioi even though it is more often evident in nie-rich blades such as KoBizen (KoBizen tended to forge at higher temperatures and render the nioiguchi more in nie / konie). It is about the shape as in fingerprint blobs on the blade. 

 

Of course - but I didn't say anything in the context of nie/nioi for jifu, did I?
My comment was directed at how jifu utsuri manifests itself on blades - exactly as you write like a fingerprint. And the reason why it is so is perhaps small variations in the carbon concentration in the steel that cause such an effect. But that's just a guess
I also agree that utsuri hardens the surface of the blade, but I'm not sure if that was the swordsmith's intention
First of all - utsuri occurs only in a very thin layer of steel and with repeated sharpening it disappears much faster than hamon
And then - I'm saying this as I heard, from a friend who has been a togishi for over 30 years
A well-forged blade will crack/break in battle due to the higher harmonic frequencies that are created in the steel when blade repeatedly hits blade against blade
To eliminate this phenomenon, the fumbari at the base of the blade is of fundamental importance

[Rayhan]

So if we add Ko-Hoki to the list we see early schools: Ko-Hoki, Ko-Bizen, Ko-Ichimonji, Yamashiro, Aoe and even Bungo that have Utsuri in some capacity. Is it not plausible to then say that if this feature was initially an accident it very soon became a consistent feature and part of the manufacturing process during Heian into Nanbokucho and slightly beyond? The steel that was made in these regions via Tatara (not the in house steels mos likely made by earlier shops) was distributed across the region and perhaps these smiths who worked in various methods had certain agreement on foundational procedure given the cross of the same raw material. How to fundamentally prepare this steel for sword making ? Perhaps the heat treatment that leads to utsuri is there because this was a tried and tested procedure for iron sands in this region?

 

The exact history of steel distribution from in-house manufacturers in Heian to Tatara in Heian and after is known but that knowledge is with Paul Martin (from an English perspective) unless there is another member who has studied the distribution of raw iron sand and mass production of tamahagane in the medieval Japan? What is clear is that the Hoki and Bizen regions were epicentre locations for iron sand and the composition is quite similar.

[AlexiG]

21 hours ago, Rayhan said:

The exact history of steel distribution from in-house manufacturers in Heian to Tatara in Heian and after is known but that knowledge is with Paul Martin (from an English perspective) unless there is another member who has studied the distribution of raw iron sand and mass production of tamahagane in the medieval Japan? What is clear is that the Hoki and Bizen regions were epicentre locations for iron sand and the composition is quite similar.

I have not found a ton in English but have had a lot of fun reading these articles and links there-in. Google translate does an OK job. Names and sword nomenclature are a bit tricky but with a bit of effort I found these articles quite interesting and illuminating. I think they will be divisive as according to the author, before Shinto most (but not all) steel was imported, and before Shinto most but not all swords were of maru-kitae construction. Some of that was mentioned on another post here and here but the Cu and Ti data seem credible (Continental/Korean steal has high Cu content, Japanese has very low Cu content).

Base material of Japanese swords

Iron Market in Medieval Japan

 

Here is a link to a technical paper on utsuri (A Hypothesis for the Mechanism that Produces the Utsuri Pattern on Japanese Swords). Have not gotten that article yet so cannot comment on how useful it is in understanding utsuri.

 

Best,

Alexi

[Rivkin]

1 hour ago, AlexiG said:

I have not found a ton in English but have had a lot of fun reading these articles and links there-in. Google translate does an OK job. Names and sword nomenclature are a bit tricky but with a bit of effort I found these articles quite interesting and illuminating. I think they will be divisive as according to the author, before Shinto most (but not all) steel was imported, and before Shinto most but not all swords were of maru-kitae construction. Some of that was mentioned on another post here and here but the Cu and Ti data seem credible (Continental/Korean steal has high Cu content, Japanese has very low Cu content).

 

More or less same method as Kimura, different to opposite results. Not enough blades destroyed for testing, especially Kamakura-Nanbokucho ones. There were periods when Japan had near zero international trade and it would exceptionally strange it would continue somehow to receive tons of iron without anyone noticing.

[Rayhan]

21 minutes ago, Rivkin said:

 

More or less same method as Kimura, different to opposite results. Not enough blades destroyed for testing, especially Kamakura-Nanbokucho ones. There were periods when Japan had near zero international trade and it would exceptionally strange it would continue somehow to receive tons of iron without anyone noticing.

I think the article on iron distribution clearly states that initially there were scattered tatara being used for iron production, which then moved to a combination of imported iron from China and Korea no doubt, then as tatara technology increased (tenpin bellows) we have a more self sufficient local supply by the edo period and finally a whole opening up of the iron trade with even European iron coming in. That's in a condensed version. It stated that the Chugoku region still maintained heavy iron sand production through the 1000 year span. That is summary.

 

I think technological changes in tatara also should be taken into account.

 

Trade didn't stop completely in the edo period, it was just very selective on who and what was allowed into Japan and from which regions.

[Lewis B]

Not sure if everyone will have access to the 2024 source paper linked by @AlexiG and the authors hypothesis regarding Utsuri and its appearance on Nihonto. So I will post a link here. 

While still conjecture on the part of the authors its good to see an hypothesis examined in detail with scientific data and for the paper (I assume) to be peer reviewed before publication.

As to why its present I agree with others here who say that for the most part it was not by accident. Without access to metallurgical testing the early smiths would have known which blades stood up to a beating in battle and those that failed, merely from a visual examination. It wouldn't take many examples to make the connection that a blade with Utsuri was more resilient (which appears to be the case) and for Utsuri to be 'engineered' into the blade to recreate those favourable characteristics of durability as an evolution, over decades and centuries, into the swordmaking process. As to why the appearance of Utsuri diminished going into the Edo period, that could be related to a shift from a focus on durability to one of aesthetics ie jihada and hamon. Far easier to appreciate a beautiful hamon line than ethereal Utsuri clouds.

Utsuri paper.pdf

[AlexiG]

48 minutes ago, Rivkin said:

 

More or less same method as Kimura, different to opposite results. Not enough blades destroyed for testing, especially Kamakura-Nanbokucho ones. There were periods when Japan had near zero international trade and it would exceptionally strange it would continue somehow to receive tons of iron without anyone noticing.

Yep. The author argued in one of the many articles that there was a lot of piracy and illegal imports. One trick was to use iron as "ballast" on the ships in one direction and replace with something else that was heavy in the other direction, so they did not have to declare the iron as imported goods it. Supposedly a new shipwreck was found, and a lot of iron was on board, which the author used as a further evidence of the theory. The theory could make sense, but yes more data will be nice.

 

Best,

Alexi

 

 

[Rivkin]

1 hour ago, Rayhan said:

I think the article on iron distribution clearly states that initially there were scattered tatara being used for iron production, which then moved to a combination of imported iron from China and Korea no doubt, then as tatara technology increased (tenpin bellows) we have a more self sufficient local supply by the edo period and finally a whole opening up of the iron trade with even European iron coming in. That's in a condensed version. It stated that the Chugoku region still maintained heavy iron sand production through the 1000 year span. That is summary.

I think technological changes in tatara also should be taken into account.

Trade didn't stop completely in the edo period, it was just very selective on who and what was allowed into Japan and from which regions.

It can, but then afaik Kimura would use related argument (Ti presence) to say koto steel is Japanese in contrast to Kofun steel and he also states that from his analysis you can find identical composition in shinto and Muromachi and the difference he argues is purely due to different forging and the resultant grain size.

For trade the first issue is that the nature of trade goods was generally recorded. There are also shipwrecks and items described as Chinese when sold in Japan. There is no evidence of iron imported until late Muromachi. Second issue there was a number of pauses which either collapsed the trade or shifted it to high price/low volume items: Mongol prohibition, Ming prohibition, pause in tributary missions and high tariffs during early Heian, etc. etc..

As a supply of iron international trade until late Muromachi should have been a fickle enterprise.

 

For utsuri study the issue is that it introduces a fully modern method to obtain utsuri instead of researching old blades. It might be very relevant, but it also might not be. As parallel, there were dozens of studies "reproducing" wootz and it turned out nearly all were just producing some manner of dark pattern, not related to historical steel. 

[Rivkin]

3 hours ago, AlexiG said:

Yep. The author argued in one of the many articles that there was a lot of piracy and illegal imports. One trick was to use iron as "ballast" on the ships in one direction and replace with something else that was heavy in the other direction, so they did not have to declare the iron as imported goods it. Supposedly a new shipwreck was found, and a lot of iron was on board, which the author used as a further evidence of the theory. The theory could make sense, but yes more data will be nice.

Ballast is how more or less officially Indian and related steel was imported by western merchants during late Muromachi to Edo. It is a well known and confirmed case. I am not aware of any pre-1500 record talking about this. Sulfur, wood, copper, silk, silver are common commodities, not a word about iron.

 

My gut feeling: there was some big change between late Muromachi and Edo, which for some reason no one can track in detail (why??). I would vote for Japanese origin of koto steel. It has region-specific look which is retained over centuries.

[Rayhan]

1 hour ago, Lewis B said:

Not sure if everyone will have access to the 2024 source paper linked by @AlexiG and the authors hypothesis regarding Utsuri and its appearance on Nihonto. So I will post a link here. 

While still conjecture on the part of the authors its good to see an hypothesis examined in detail with scientific data and for the paper (I assume) to be peer reviewed before publication.

As to why its present I agree with others here who say that for the most part it was not by accident. Without access to metallurgical testing the early smiths would have known which blades stood up to a beating in battle and those that failed, merely from a visual examination. It wouldn't take many examples to make the connection that a blade with Utsuri was more resilient (which appears to be the case) and for Utsuri to be 'engineered' into the blade to recreate those favourable characteristics of durability as an evolution, over decades and centuries, into the swordmaking process. As to why the appearance of Utsuri diminished going into the Edo period, that could be related to a shift from a focus on durability to one of aesthetics ie jihada and hamon. Far easier to appreciate a beautiful hamon line than ethereal Utsuri clouds.

Utsuri paper.pdf 1.73 MB · 4 downloads

It could also be the way steel or tamahagane was manufactured. Higher temperatures in smelting removing more impure areas and giving smiths a more uniform raw material. I also suspect, like everything in Japan, that these process was standardised in the later years after the Muromachi when iron distribution within Japan was quite tightly controlled.