NHK TAMAHAGANE DOCUMENTARY

[Guest Simon R]

I thought you might be interested in this NHK documentary about the making of Tamahagane.

It's fascinating, not only for the sheer hard work which goes into the process but, quite unusually, this documentary also shows what can potentially go wrong.

 

https://www3.nhk.or.jp/nhkworld/en/ondemand/video/4001416/

[French nihonto]

Very good report from nhk!
I take advantage of your post to share a recent video about an incredible story about the nihonto

 

Max.

[Michaelr]

Wow Simon that was great.  Thank you for sharing

  MikeR

[lonely panet]

 YEAH BRASS HANDLED TYPE 95'S  AHAHAHAHHAH

[French nihonto]

2 hours ago, lonely panet said:

 YEAH BRASS HANDLED TYPE 95'S  AHAHAHAHHAH

yes the parts shown are of little interest. but the story about the unfortunate destruction of the blades (old and recent) in big fires, is quite impressive.

[lonely panet]

when 1 part of the story is horse plop,  then whats the rest??

[Guest Simon R]

50 minutes ago, lonely panet said:

when 1 part of the story is horse plop,  then whats the rest??

NHK destroys what little remains of my street-cred yet again. 🤦🏻‍♂️

[Larason2]

I thought the first video was a fascinating video, and I thank the OP for posting it. I watched it with my 4 year old daughter, and she also thought it was fascinating. She kept asking me: why are they getting burned?

 

I can’t help but feel though that a big part of the difficulties they have is the process itself. 

 

One part is the leadership of Kihara Akira, the murage. He provides some direction, but I don’t think his direction is very effective. They produced perfect tamahagane on one side of the furnace, but he says it doesn’t look good initially. They seem afraid to ask him questions. Also, they literally have someone with a PhD in metal extraction from ore, and he just sits there and doesn’t ever say anything. Horio is the best sand adder, so really he should just add all the sand, and the other workers should take care of his other duties, which he doesn’t do as well. Miura is the best manager, so that is what he should be left to do. He’s not bad at adding sand, but not as good as horio. 

 

Another part is that they make a lot of mistakes because of exhaustion. This is partly because the furnace is too big, and takes too long to finish the process. As has been mentioned elsewhere, they never get good tamahagane in the middle of the tatara. It only makes sense to make the tatara narrower, which will take less time to complete. Also, it’s clear they’re still working out the process. When this is occurring, it makes sense to run smaller test runs to perfect the process, then only run the big run when everything is optimized. If they run a tatara at 1/4 the size four times, and have everyone do what they’re good at, they’ll get the really good tamahagane every time, and they won’t be so exhausted each time. Apparently this is what was done in the past, they only went to bigger furnaces to try to increase efficiency. They show the students how they do it with a smaller smelter, so clearly it is possible!

 

Other problems with the process is the charcoal management. The charcoal managers are experts, but they are rarely consulted, though the quality and positioning of the charcoal is clearly essential to the process. Really, they should sort all the charcoal by size before the process starts, and be always strategically adding charcoal. Instead, they just get big scoops of it and dump it in, even though the charcoal handlers know that isn’t the best idea. At one point in the back they threw a lot of big pieces of charcoal in, which helped temporarily with a problem, but then that ruined that layer of the tamahagane. It's probably better to strategically add charcoal from the start.

 

There are lots of design optimizations that could be made. For one, they need a better way to manage the slag. Slag viscosity isn’t a mystery, the lower the melting point of the slag constituents, the less viscous the slag will be. One part of this is how the sand is added, if they add too much iron sand near the yujiana, it will increase the melting point of the slag there, causing it to plug. To help prevent this, they can use graphite or ceramic guides to make sure the iron sand only falls where it should. Another part of this is they can add materials with low melting points to help thin out the slag. I think it’s interesting that they only added salt on one side of the tatara, and that’s the side that the slag flowed better out of. The melting point of sodium is 97.79 degrees C. Why don’t they just use more salt? I guess it's not that great to be inhaling a lot of chlorine gas, but there must be something they can add that will help.

 

Also, what some european bloomeries do is to stack the ore and the charcoal in the furnace before. If they design a matrix that holds the sand appropriately, they can integrate some iron sand into the tatara before the process even starts, which will increase efficiency and help to ensure the outcome.

 

Also, their ability to deal with the slag is limited by their strength, the limits of the tools they are using, and the strength of the clay walls. In industrial processes, the machines are designed to automatically manage the slag so humans don’t have to. If they built the furnace walls and designed a machine to automatically drain the slag from them, they will get more consistent results. They could also design better slag clearing tools that don’t take as much strength to use. The yujiana’s are also pretty small. If they use better materials than clay for that portion of the smelter, they can make bigger yujiana holes that will be easier to drain. It’s clear that using clay bricks is a liability in this process, since they are frequently at risk of breaking/leaking/falling over, and it’s hard to make yujiana holes that are big enough. They can design furnace walls with graphite or other ceramics like they do in industrial processes to make that portion of the furnace more reliable. 

 

The air supply is also a problem, as if the slag blocks the air entry, it can ruin the process. They should design multiple air holes vertically, and have a system where the air can be shunted higher if an air hole is blocked, even if only temporarily, to help ensure even quality of smelting. For instance, they can use ceramic wool to make the air lines so they are flexible. Also, it seems to me that air flow out of the system will probably make a difference. Most Japanese forges have a fume hood, if they had a fume hood and managed the exhaust of gasses with fans it would probably make the system more efficient. They could also use fans or bellows to keep the air flow in steady as well, which would probably significantly decrease the time it takes to complete the smelting. These components could be reused each time.

 

Let’s not forget that the tatara process was established to increase efficiency of iron production, and that prior to that they used smaller smelters that achieved the same thing. They also did dozens of runs, one after the other, so the crews became skilled quickly. By the time a year rolls around, a lot of the workers have forgotten what they did last year. Better to use the iron sand and charcoal in smaller batches with a more guaranteed result. 

 

But let’s say they implemented all the improvements (I’m sure they could think of more!) and greatly increased the yield of good quality steel the furnace makes. Would it still be tamahagane? Tamahagane is worth 1000 times the price of iron smelted in an European bloomery. I think the constituents of the iron sand make a difference (among them the titanium), but I think also part of the value is the mystery and the difficulty of producing it. Someone looking at the more efficiently produced iron would probably say it’s not as good, just because the process was tampered with!

 

I also thought it was fascinating that they tried to teach youngsters about tamahagane with a smaller furnace, but they didn’t want to get dirty or burned. It was a fascinating contrast, because it’s actually reasonable to not want to work yourself to exhaustion and get burned and dirty in the process! However, their sheer grit was admirable. It’s also frustrating to put so much time and effort into a process, without knowing if it’s going to turn out! Most of the crew is older, so who is going to take it over once they retire or die? Clearly it only operates with substantial financial input from the iron refining company, the tamahagane itself doesn’t pay for the process. So doesn’t it make sense to improve efficiency, to increase feasibility?

 

Well, this was my first post and it just might get me banned, but I couldn’t help it! Still, I think it is a fascinating process. I just can’t help but think there’s a better way! I don't think that iron smelted in the factory shown is as good as tamahagane, but there must be some kind of middle ground. Here’s a source I was talking about:

 

https://www.tf.uni-kiel.de/matwis/amat/iss/kap_b/backbone/rb_6_2.html\

 

The author also posits numerous refinements to the tatara process in the articles, among from I probably picked some up.

[rematron]

Lots of great discussion points, Carlos.  I look forward to seeing input from other members.  Also, congrats on your first post.  I don't think you'll get banned for a valid observation.  hahaha.  If you wanna get banned you need to learn how to be a super troll. 

[Brian]

As mentioned, why would we ban someone for an opinion or for giving an analysis?
Welcome to the forum, your input is appreciated.

[DoTanuki yokai]

I can imagine it is like the making of a shrine sword, of course they could easily light the forge with a lighter but they decide to let a shinto priest drill some shinto wood tools together till they are hot enough to light some paper and carry this from the shrine to the forge in a small lantern. 
 

Or another reason could be if you try to optimize the Tatara process where would you stop ? 
I think they made Tamahagane in electric heatet furnances for gunto in Ww2. 
let’s go a step further and make modern steel 

And many smiths make their own Tamahagane in different Tatara so I don’t think there is a supply problem. 

[OceanoNox]

11 hours ago, Larason2 said:

Still, I think it is a fascinating process. I just can’t help but think there’s a better way!

You are completely right. And your comment also raises the question of a hierarchy where juniors dare not contest the senior's opinion, and whether the senior is always the best person for advice (there was a joke on PhD comics where the supervisor messes up his student's experiments because he hasn't actually done experiments for years) (as an aside, my Japanese professor also commented that it's a sign of bad leadership, when the decision-making seniors do not allow input from the "boots-on-the-ground" juniors (and technically, drinking parties are the way to do it, so you can excuse the rudeness with the intake of alcohol)).

I think that the whole point of the exercise is to do it as "analog" as possible, and to rely on as little technology as possible. As for why they don't do more small tatara, I suppose that there is a time constraint. This specific place is, as far as I know, operated by Hitachi Metals (now Proterial?), and so the engineers doing the work may not be able to allowed to do it for longer. But as others have said, some smiths make their own tatara (some in oil drums lined with clay). 

[bjmoose]

Really fascinating.  Hopefully, the respect for old traditions will continue for a long time to come.  Looked like there were a few youthful faces among the apprentices, so the work has a chance to carry on.

[vajo]

Interesting movie. 

 

 

But as it is with old stories. Something is true, something is wish, something is fantasy. Thats why such old people are so fascinating. 

Thanks for sharing. Very sympathic man.

[Toryu2020]

Excellent points Carlos - 

When I was interviewed for this documentary the first thing out of my mouth was "its not magic", I think they turned the camera off after that...

 

-t

[ckaiserca]

On 3/7/2023 at 11:05 AM, Larason2 said:

Well, this was my first post and it just might get me banned, but I couldn’t help it!

Nah. You have presented a well-reasoned post with some interesting thoughts. That's what this forum is all about. If you want to get banned, you need to tell everyone that you are an amateur sword polisher and you learned everything you know from a Youtube video.

[Larason2]

Thanks all! Haha, I am actually a wannabe amateur sword polisher, but I think it's a crime to damage a real nihonto this way, so I'll confine my experiments to reproductions! There's really no way to polish a nihonto the way they do it without the training they have, and without the time they take to do it. The truth is also that there aren't really any youtube videos that provide any kind of useful information on the process. I've looked! Even if there was, there's no way you would be able to do it without the skills they have acquired. The problem is that I admire nihontos without the budget to buy one, and I'm a bit of a tinkerer, so I want my reproductions to look more like one!