Creating utsuri

[Rivkin]

I doubt someone would use thermocycling. Especially on a "production" and not a single "test" blade.

There might be sense that in a steel with drastically varied carbon content you might do double quenching with different temperature gradients since the optimal point is going to be different.

[C0D]

45 minutes ago, Franco said:

 

If you know how to look at utsuri why are you asking me?

 

But, since you asked, utsuri? No, perhaps an utsuri like effect. Which is not the same. Saiha gives an utsuri like effect, but it's not utsuri according to Yamanaka. Effect is not the same as what my eyes are seeing. Even when you do see utsuri, it becomes apparent that certain types of utsuri are quite intentional. While other types are more incidental. 

 

 

Just to understand, is this utsuri to you? 

[Rayhan]

19 minutes ago, Rivkin said:

I doubt someone would use thermocycling. Especially on a "production" and not a single "test" blade.

There might be sense that in a steel with drastically varied carbon content you might do double quenching with different temperature gradients since the optimal point is going to be different.

Sorry, but thermocyling was done before or in cases after the hamon shape was created or decided. The article by Kapp speaks of exactly that, cycling varied temperatures. It is a feat tentamount to mythical magic if done by eye and not using spophisticated sensory equipment like we have today. I think once you read up on the many varying ways thermocycling can be done and many types of cycling it will make more sense. 

 

Koto blades were not made for art only. 

[Tohagi]

A usefull tip to evaluate normalisation tempreature is hearing the snap when touching with wet fingers in various parts of the blade.

 

Very impressive when à traditional smith do so...

 

Eric VD 

[C0D]

2 minutes ago, Rayhan said:

Sorry, but thermocyling was done before or in cases after the hamon shape was created or decided. The article by Kapp speaks of exactly that, cycling varied temperatures. It is a feat tentamount to mythical magic if done by eye and not using spophisticated sensory equipment like we have today. I think once you read up on the many varying ways thermocycling can be done and many types of cycling it will make more sense. 

 

Koto blades were not made for art only. 

Kapp never mentioned cycling in the book, it's heating at different temperatures at the time of yakiire, which is the same I said in my first post.

So if nobody did that in modern times, how do you know it was made that way back then?

 

[Matsunoki]

56 minutes ago, Franco said:

No, perhaps an utsuri like effect. Which is not the same

So what actually is this utsuri like effect? In what way is it not the same? Method of production (there seems to be several), metallurgical structure? Be good to know what looks like utsuri but isn’t.
@COD has the benefit of having the blade in hand vs working from images….plus he saw the smith at work.

In what way is koto utsuri higher quality? Does it improve flexion tolerance? Does it improve cutting? Does it improve longevity.

Observing this interesting topic (as a real novice)  it seems we have very few hard facts but a great many opinions.

[Kiita]

In support of the differential heating theory, I've actually seen it appear accidentally on non-sword cutting tools before, apparently in that way. Why would it be done that way? It might have originated as a byproduct of smiths very carefully watching the edge temperature to prevent grain growth from overheating and excess soak time, which would reduce toughness, in the same way that fine grained nioi hamon were considered tougher than nie. No need to risk grain growth at the thin edge by waiting for the whole blade to come to temperature if you're only intending to harden part of it anyway. A cool looking result is discovered in polishing and then it becomes a desired feature swordsmiths work to optimize. Another just-so-story but it seems as likely as any.

[C0D]

19 minutes ago, Matsunoki said:

So what actually is this utsuri like effect? In what way is it not the same? Method of production (there seems to be several), metallurgical structure? Be good to know what looks like utsuri but isn’t.
@COD has the benefit of having the blade in hand vs working from images….plus he saw the smith at work.

In what way is koto utsuri higher quality? Does it improve flexion tolerance? Does it improve cutting? Does it improve longevity.

Observing this interesting topic (as a real novice)  it seems we have very few hard facts but a great many opinions.

I'd say with the same steel a blade with utsuri has more resilience, so can withstand hits without breaking, more than a blade without.

Sharpness is due the hamon so not directly influenced by utsuri.

I agree with Kiita saying that first times could had been accidentally created by trying to avoid heating the blade too much and for too long time, but then became a feature when they figured out it worked better on the battlefield 

 

[Rayhan]

@C0Di think the glass is full. But that is ok.

 

@Matsunokiyou raise wonderful questions. The fact that we should admit cycling happens at every part of the manufacturing process intentional or not is to be kept in mind. The original billets will have their presentation, after amalgimation their presenation will change, after further cycling you will see another change and so on and so on till Yaki-ire when the final form is determined. Remember that there are many forms of Utsuri as mentioned by other members, some intentional and some by trial and discovery. We should move to specific Utsuri then, perhaps @C0Dcan begin by showing specific examples and we can the discuss at what point these were probably made. Every Koto school that produced utsuri or smith had their own process remmeber. But it is for all intensive purposes a method of preserving the steels quality, reducing stress and the utsusri effect is a bi product of that methodology.

[C0D]

1 minute ago, Rayhan said:

@C0Di think the glass is full. But that is ok.

 

@Matsunokiyou raise wonderful questions. The fact that we should admit cycling happens at every part of the manufacturing process intentional or not is to be kept in mind. The original billets will have their presentation, after amalgimation their presenation will change, after further cycling you will see another change and so on and so on till Yaki-ire when the final form is determined. Remember that there are many forms of Utsuri as mentioned by other members, some intentional and some by trial and discovery. We should move to specific Utsuri then, perhaps @C0Dcan begin by showing specific examples and we can the discuss at what point these were probably made. Every Koto school that produced utsuri or smith had their own process remmeber. But it is for all intensive purposes a method of preserving the steels quality, reducing stress and the utsusri effect is a bi product of that methodology.

I already showed several examples, but apparently they're not utsuri?

I'm not trying to fight or being petty, just I'm sharing my first hand experience, and those who say I'm wrong provided no evidence of what they're saying.

 

[Lewis B]

43 minutes ago, Kiita said:

In support of the differential heating theory, I've actually seen it appear accidentally on non-sword cutting tools before, apparently in that way. Why would it be done that way? It might have originated as a byproduct of smiths very carefully watching the edge temperature to prevent grain growth from overheating and excess soak time, which would reduce toughness, in the same way that fine grained nioi hamon were considered tougher than nie. No need to risk grain growth at the thin edge by waiting for the whole blade to come to temperature if you're only intending to harden part of it anyway. A cool looking result is discovered in polishing and then it becomes a desired feature swordsmiths work to optimize. Another just-so-story but it seems as likely as any.

Very true. First time I came across the term 'Utsuri' was in relation to a honyaki chef knife I purchased 7 years ago. The maker had referred to this feature in his description for the W2 tool steel blade as an indicator of the perfect heat treatment conditions.

 

[Rayhan]

Generally if you have modern steel then utsuri is just for decoration rather than function. It will appear in a different, more flamboyant manner. Modern steel does not require this for serious function. 

 

@C0Dyou have an excellent visual library, can we begin one step at a time from your library please? 

[C0D]

16 minutes ago, Rayhan said:

Generally if you have modern steel then utsuri is just for decoration rather than function. It will appear in a different, more flamboyant manner. Modern steel does not require this for serious function. 

 

@C0Dyou have an excellent visual library, can we begin one step at a time from your library please? 

I have close to 1TB in my library, you gonna need to be more specific on what you want me to show you.

 

Meanwhile can you show me some examples of what you assume is an utsuri created by thermal cycling?

[Lewis B]

26 minutes ago, Rayhan said:

Generally if you have modern steel then utsuri is just for decoration rather than function. It will appear in a different, more flamboyant manner. Modern steel does not require this for serious function. 

 

@C0Dyou have an excellent visual library, can we begin one step at a time from your library please? 

I certainly wouldn't equate the utsuri 'effect' created with modern steel with that seen on early Koto tamahagane blades so being more specific wrt to the type of utsuri will be beneficial for this discussion.

[Jacques]

Steel is iron and carbon, whether old or new: an atom of iron is an atom of iron and an atom of carbon is an atom of carbon. The creation of utsuri must be sought in temperature control. Why is utsuri attached to a hamon in nioi deki? 

[Rayhan]

2 hours ago, C0D said:

I have close to 1TB in my library, you gonna need to be more specific on what you want me to show you.

 

Meanwhile can you show me some examples of what you assume is an utsuri created by thermal cycling?

All Utsuri and all Nihonto involve some level of thermocycling, sorry @C0D

[Rayhan]

@C0Dshall we begin with Midare Utsuri from your photographic database please? Perhaps then you can present some very strong examples of Choji Utsuri.

 

Later we can try Bo Utsuri if you can please? 

 

I look forward to seeing these 

[C0D]

7 hours ago, Rayhan said:

It has been a very long time since i had an inkling to comment on the board but since i am in Japan and saw some amazing Nihonto i just dropped by and saw this very interesting topic.

 

Utsuri is a result of the process of thermocycling the steel in different intervals befor yaki-ire. Koto smiths could not afford to make mistakes with their steel. Tamahagane was not in abundance (still isn't) and so thermocycling was used as a way to reduce any risk of issues when quenching. What we must do is look at the direct meaning of Utsuri (to change, to transition) those who own Koi will also understand Utsuri and its meaning. 

 

The swords were clay coated in cases and put through thermocycling many times before being quenched. New clay is applied at various intervals, removed and reapplied. This takes time and precission. This produces varying hardness at mm dissipation throught the koto blades.

 

In the later Edo period swords were made in different styles and made in more flamboyance with an emphasis on hamon and the Shinogi was not really part of the same outer jacket of the sword overall so this process was cut back. This also made production of blades faster (no doubt the lessons of cutting corners in the Muromachi period). 

 

And so those smiths that reproduced Utsuri in the Edo period and now are following an extensive, time consuming process when making their blades.

 

 

Of course any form of hardening is a thermocycling, because it changes the composition of the metal through heating and rapid cooling, what I mean is that specific process you described in your first post.

Can you provide an example of blade made that way and how you know that process has been used on it?

[Brian]

Also not sure what the argument is here. The process of making Nihonto consists of thermo cycling. The only difference is how much and how exactly, when we are talking about utsuri. But the process of repreated heating and cooling, and quenching, is essentially thermocycling. So you can't argue that it doesn't happen, that's how you get a hamon and hataraki. Now you can debate how they do the thermocycling to achieve utsuri, but you can't debate whether it happens or not at all.

[C0D]

1 minute ago, Brian said:

Also not sure what the argument is here. The process of making Nihonto consists of thermo cycling. The only difference is how much and how exactly, when we are talking about utsuri. But the process of repreated heating and cooling, and quenching, is essentially thermocycling. So you can't argue that it doesn't happen, that's how you get a hamon and hataraki. Now you can debate how they do the thermocycling to achieve utsuri, but you can't debate whether it happens or not at all.

Exactly, any form of forging and hardening is a thermocycling, but what he stated in his first post is a series of process of heating and cooling with application of clay prior to the yakiire that would lead to the creation of utsuri. 

I just want to know where this information comes from and how it should look like when it's done.

Because so far the only way I know to create utsuri is by temperature control during yakiire. It's not something I claim, it's been done by several swordsmiths, not only Japanese 

[Rivkin]

Repeated quenching? I must be missing something. There can be an argument for two separate quenching procedures under some circumstances, but that would still be not too common.

[Brian]

I have seen videos where Nihonto are quenched more than once, I think it is more common than you think.
Also, in Markus' essay on utsuri, he quotes:
 

Quote

Another interesting approach to explain utsuri can be found in the „Kentô-kikigaki“ (見刀聞書) from Tenpô 14 (天保, 1843). Therein we read: „By plunging the heated blade into water, the clay coat contracts. When the blade is now plunged into the water a second time, the now exposed areas cool down faster than the upper areas which are still covered with clay. This produces utsuri.“

 

[C0D]

14 minutes ago, Rayhan said:

@C0Dshall we begin with Midare Utsuri from your photographic database please? Perhaps then you can present some very strong examples of Choji Utsuri.

 

Later we can try Bo Utsuri if you can please? 

 

I look forward to seeing these 

 

Midare utsuri 

 

Bo utsuri 

[C0D]

Just now, Brian said:

I have seen videos where Nihonto are quenched more than once, I think it is more common than you think.
Also, in Markus' essay on utsuri, he quotes:
 

 

I would say not a common way to make utsuri, also not much reliable, but it still can work, since the principle is the same, different temperatures when cooling rapidly 

[Rayhan]

13 minutes ago, C0D said:

Exactly, any form of forging and hardening is a thermocycling, but what he stated in his first post is a series of process of heating and cooling with application of clay prior to the yakiire that would lead to the creation of utsuri. 

I just want to know where this information comes from and how it should look like when it's done.

Because so far the only way I know to create utsuri is by temperature control during yakiire. It's not something I claim, it's been done by several swordsmiths, not only Japanese 

Please give me a moment im busy with this

[Rivkin]

Twice quenched - possible. Not under any circumstances, but under some, possible. More - runs into some fundamental issues.

By the same token, annealing is common as part of technological process. Quenching is somewhat common. Thermocycling... No. For test purposes on couple of samples - yes, as part of production process on a shipped part I am struggling to image the circumstances.  Can be micrometer scale laser-induced hardening - basically super exotic.

Can be hair splitted by calling "micro-thermocycling" almost anything, anything heats and cools a little bit, but then its not a discussion about technology.

 

There is a common thing which is multi-stage annealing where you heat the sample and then slowly cool it off - but "heat" in this case is done slowly and not to very high temperature. and cooling is done much slower. No quenching, no heating red hot, the purpose is gradually reach the ground state without much martensite or stress.

[Hoshi]

This is a wonderful topic, and I appreciate all the photos and references being shared.

 

Lovely to hear again from you @Rayhan. Welcome back. 

 

I am still not sure myself how utsuri was obtained, but I (weakly) subscribe to the temperature-control theory and single quench, so far at least. Annealing, thermocycling, are two plausible alternative theories. 

 

I believe the focus should not be utsuri - but rather, antei - the dark band above the hamon. How was antei obtained, and how does it differ metallurgically from the white-ish band above? (utsuri). I believe this is important, because the utsuri itself is the default jigane state whereas the Antei is where the metallurgical alterations of interest occur. 

 

I have not seen a convincing metallurgical analysis comparing the three bands: hamon, antei, and utsuri. This is an important gap. I would be very grateful for a credible reference to come to light. 

 

Regarding a photo of utsuri, here is a striking midare-utsuri on a Tokubetsu Juyo blade by Osafune Kagemitsu (photography credit to Ted Tenolds). This is a good base to anchor the conversation. 

 

Notice the 3 distinct bands:

- Hamon (and the nioi-based substructure forming the nioiguchi and the ashi)

- Antei (the dark area above the nioiguchi)

- Utsuri (the whitish area above the utsuri)

 

 

 

 

[Rayhan]

So, back to this. 

 

@Rivkinthermocycling yes. Please stop putting the cart before the horse. We do not need to speak of Yaki-ire at all when we speak of Utsuri. 

 

The development of a blade has its stages and if the smith uses thermocycling (annealing is a process that is involved also but not mutually exclusive) 

 

https://knifesteelnerds.com/2021/08/28/how-to-thermal-cycle-knife-steel/

 

I know knife steel nerds is not a scientific journal but this article helps. 

 

If we imagine the process where we are changing the structure of the steel as we go along all the way till Yaki-ire then we can build the visual base for utsuri. @C0Di am not fortunate enough to see Utsuri being produced in real life today, being produced infront of my eyes to say, however, if you have this information please share it here so we can all benefit. I can say that i have an Ichimonji blade and Aoe that both have wonderful Utsuri and will share that when i am close to them again after my travels. 

 

 

[Rayhan]

Just now, Hoshi said:

This is a wonderful topic, and I appreciate all the photos and references being shared.

 

Lovely to hear again from you @Rayhan. Welcome back. 

 

I still not sure myself how utsuri was obtained, but I (weakly) subscribe to the temperature-control theory and single quench, so far at least. Annealing, thermocycling, are two plausible alternative theories. 

 

I believe the focus should not be utsuri - but rather, antei - the dark band above the hamon. How was antei obtained, and how does it differ metallurgically from the white-ish band above? (utsuri). I believe this is important, because the utsuri itself is the default jigane state whereas the Antei is where the metallurgical alterations of interest occur. 

 

I have not seen a convincing metallurgical analysis comparing the three bands: hamon, antei, and utsuri. This is an important gap. I would be very grateful for a credible reference to come to light. 

 

Regarding a photo of utsuri, here is a striking midare-utsuri on a Tokubetsu Juyo blade by Kagemitsu, photography credit to Ted Tenolds. This is a good base to anchor the conversation. 

 

Notice the 3 distinct bands:

- Hamon (and the nioi-based substructure forming the nioiguchi and the ashi)

- Antei (the dark area above the nioiguchi)

- Utsuri (the whitish area above the utsuri)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This is now an amazing example, what we should be wishing to see here is how the clay was placed in various intervals of heating. If only we had that time machine Darcy spoke of so often

[Rivkin]

4 minutes ago, Rayhan said:

So, back to this. 

 

@Rivkinthermocycling yes. Please stop putting the cart before the horse. We do not need to speak of Yaki-ire at all when we speak of Utsuri. 

 

Ok, so what is defined as thermocycling? Multiple quenchings? Above two - would love to see an example. 

If its not quenchings, then we are probably in multi-stage annealing territory? Which is a big topic of its own, with often multi-days timeframe... and I don't know if it relates to utsuri or not, and how much use it saw in Japan at all.