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Nihonto material reuse


Ken-Hawaii
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Swords & other weapons broke, but how was the material reused? Tamahagane was too precious, a few hundred years ago, to just throw it out, but I've never seen any discussion on how it was reused.

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Ken,

an interesting question!

Of course you can use any scrap metal to forge something suitable. With broken blades you have a steel mix with widely varying carbon content, so I think it could be used to make SHINGANE for new blades. Many swordsmiths had - and stll have - their own OROSHIGANE kiln, so it is always possible to recycle any type of steel. Depending on the material that you feed into this kiln, you can produce different grades of steel. The resulting KERA will mostly resemble the traditional TAMAHAGANE. 

It is also known that broken blades were transformed into smaller blades, not only for 'military', but as well for household use.

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As Jean adds above, many blades were repurposed, into shorter blades, blades for cutting flowers in tea ceremony too, (especially if they had a good Mei), etc. I have also seen a collection of old Nakago with Mei.

 

Even in Japan I have recently seen experimental transformations made with old broken blades into hunting or camp knives.

 

(A Wakizashi I have in formal Koshiraé looks to have once been a full-length Yosozaemon Sukesada blade.)

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I understand the repurposing, but I'm thinking about early/mid Muromachi, when tosho were scrambling to make as many blades as possible. The tatara process isn't true smelting, as I recall, so would broken blades just be dumped in with the masa satetsu? That wouldn't allow for much control of the tamahagane.

 

That may be the answer, based on sheer need, but I'll bet there was some type of processing after a battlefield was cleaned up.

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5 hours ago, Ken-Hawaii said:

......I'll bet there was some type of processing after a battlefield was cleaned up.

Yes Ken, you are correct. That is the OROSHIGANE GAMA I mentioned above. These look like small bloomery furnaces, and today they mostly work with normal forge blowers. Nowadays, the smiths often build them with a metal jacket so they can re-use them multiple times. Simple versions are just built on the ground with stones and lots of clay. 

You can fill it with different types of steel, even scrap metal, but in Japan, they try to use (pure) old iron that was previously made from traditionally processed TAMAHAGANE. Anchor chains, old nails, old tools can be used to get a steel that is very close to TAMAHAGANE. Old broken TETSUBIN (water kettles) are used to introduce more carbon into the steel, depending on what type you need. Working temperature is as high as 1.300°C or higher, so iron will not be melted, but sintered as in the TATARA process.  

TAMAGAGANE is very pure concerning alloy metals, but it has widely varying carbon content and some silica (from the slag) which can be driven out in the refining process.

For your information, I attach a photo of such an OROSHIGANE GAMA in construction.  In the end, it will not be much higher. 
 

Ausheizofen 1403.jpg

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Thanks, Jean. That's very interesting, & I'm surprised I hadn't heard about it.

 

So the Muromachi tosho used these Oroshigane Gama to create Shingane for Nihonto, right? I assume that Kawagane would require better control of the steelmaking process (i.e., Tamahagane from a tatara).

 

Can this process be tied in with the Kazu-Uchimono that appeared during this period? There were a lot of factors that led to the demise of Kamakura blade techniques, & this sounds like one of them. In other words, since Kamakura tosho techniques were passed down through word-of-mouth, I'm hoping to eventually write a paper on how & why these techniques were lost in time, because there was so much else going on (like Daimyo demands for more blades, at any cost!).

 

The quality of steel (or lack thereof) from this "field experient" process would certainly seem to be inferior to Tamahagane, & I'm getting a better handle on why several of my Muromachi blades have inconsistent jigane.

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Ken,

I am not sure that an OROSHIGANE GAMA necessarily produces inferior material, and the same applies - in opposite direction - to TATARA. Because of their size, TATARA need a team of experienced and knowlegeable workers to prevent failure. A small refining kiln (OROSHIGANE) can be built and operated alone. In both cases the resulting KERA (bloom block) is not homogeneous and will have to be worked on very carefully. If you don't do this, your steel will not have predictable properties.

As I tried to explain, operating an OROSHIGANE furnace successfully depends mainly on the iron material used. You don't have the direct reduction process to transform SATETSU into iron which takes some time. You just have to keep the temperature up to the correct level and feed good iron. Slightly higher temperatures and a lot of charcoal may even increase the carbon content so you can produce high grade steel. But most probably many 'wannabe' swordsmiths of that period did not have access to good steel, and in addition to that, not enough knowledge about steel in general. We have to consider that metallurgy was not known in Japan until the beginning of the industrialization!

I could imagine that the appearance of so many KAZU UCHI MONO on the arms market of that belligerent period had several causes. It seems that less qualified smiths tried to take their piece of the 'cake', offering cheap swords made in a cheap way. We have to remember that special information about sword-making was not available except from a master smith, and understandably these kept their secrets to maintain their position. But there was certainly a general knowledge about knife forging, fire-welding and laminating techniques as well as about the hardening and tempering process. But what worked sufficiently with household knives and cutting tools for craftsmen is not necessarily good enough for the manufacture of sword blades which had to be resilient while keeping a very sharp edge at the same time.

Refining the steel components for a blade and the heat treatment after the forging process were (and are still) very special and need time and a lot of experience. Any shortcuts in the process will inevitably lead to failure, and so I am convinced that the lack of special expertise and faulty heat treatment of sword blades were the main reasons for bent or broken blades besides unsuitable or low quality material. 

Hope that helps a bit! 

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Is there any way that an Oroshigane blade is identified as such? I think that most collectors, including myself, expect a Koto blade to be created from tamahagane, originating from a tatara. Jean, you're making the case that my assumption is likely short-sighted. So, now I'm wondering how we can know the (for lack of a proper phrase) "original provenance" of a blade. Does it matter? Have they been papered by NBTHK?

 

Thinking that one of my TH or juto blades may have originated from a (literal) hole in the ground is making me twitch!  :freak:

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34 minutes ago, Ken-Hawaii said:

Is there any way that an Oroshigane blade is identified as such? I think that most collectors, including myself, expect a Koto blade to be created from tamahagane, originating from a tatara. Jean, you're making the case that my assumption is likely short-sighted. So, now I'm wondering how we can know the (for lack of a proper phrase) "original provenance" of a blade. Does it matter? Have they been papered by NBTHK?

 

Its more about old papers; unless its written down in the signature NBTHK has no way to clearly know what's the original source of the steel used. There are armor pieces, swords with old testaments as being made from old blades or old muskets. At the time the emphasis on tamahagane was non-existent. Swords could be made from whatever iron sources, some considered a bit more fashionable. Namban tetsu, anchors, "old recipes" including mixing tamahagane with gold dust. 

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Ken,

you are educated in chemistry, aren't you? Molecules don't have tags on them to testify their 'biography'! Steel is steel, and if it's pure and correctly handled in the forge, it will have the intended properties. OROSHIGANE might on occasions even be 'better' than TAMAGANE, and indeed, it is no less 'traditional' than the latter. Iron was always precious and has been recycled by the smiths all over the world. Our today minds are focused on 'useful' and 'waste' materials, but iron is nothing to throw away; it is always iron and precious.

So you should not look too much at the material side of blades (which we don't know anyway!) but at the workmanship. That is what makes a tool useful or a sword a good and reliable weapon!

 

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Chemical Engineer, Jean, but close enough. My Chemist wife wife will correct me, anyway!

 

I think we're closing in on what's bothering me. If we were actually SMELTING steel, & able to purify it (vs just adding more carbon), then I would agree that Oroshigane could be as "pure" as Tamahagane. But I can't see how a hole in the ground can provide as many controls as a tatara. Maybe I should hide the jewel-like chunk of tamahagane that's sitting on my desk, front & center, so it doesn't remind me of its purity, whatever we define that as.

 

Of course, my initial question was adequately answered by you, in that I wasn't familiar with the Oroshigane process. But rather than being suitably grateful, here I am picking on steel purity. Ah, well.

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I can understand that. Looking at a juwel-like chunk of steel makes you easily believe it is pure, but in fact, TAMAHAGANE is not clean. It is almost free of alloying elements because of its low manufacturing temperature, but it contains impurities like silica. The reason for the many folding and fire-welding actions in the forging process is not to keep the smith working, but to minimize these impurities and homogeneize the carbon content. 

Depending on the grade of the TAMAHAGANE you can buy, this might be no less work than that with OROSHIGANE.

Referring to what I said above about 'Iron is iron', I gave some of my precious bloomery iron (made in a celtic bloomery furnace) to ASANO TARO (  http://asanokajiya.com/ ) which he used in making his blades. He said that it was quite good in quality and useful.

Knowing this, I would not hesitate to buy one of his beautiful blades, though.

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On 7/1/2022 at 6:08 AM, Ken-Hawaii said:

I think we're closing in on what's bothering me. If we were actually SMELTING steel, & able to purify it (vs just adding more carbon), then I would agree that Oroshigane could be as "pure" as Tamahagane. But I can't see how a hole in the ground can provide as many controls as a tatara. Maybe I should hide the jewel-like chunk of tamahagane that's sitting on my desk, front & center, so it doesn't remind me of its purity, whatever we define that as.

 

Welcome to the world of pre-industrial processes.

 

I spent a significant amount of my career a) evaluating pre-industrial processes in the developing world and b) educating/arguing with modern engineers and scientists about what form pre-industrial processes take.

 

The first thing to get over is to quit thinking about how the "hole in the ground" provides controls. The controls are provided by the skilled craftsman who has developed the ability to control inputs in a way that exceeds modern rationality. 

 

As I stated in a prior thread, the input control started when he was a child, cleaning up around the shop for his teacher.

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