koa isshin mantetsu hada

[lonely panet]

i know its hard to photograph tigh fine hada but can peaple post examples of there hada, Bruce is chasing dates but has over looked ji-hada. 

[Bruce Pennington]

Here's mine: (hmm, a bit out of focus.  Looks like the camera focused on the surface behind the blade.  I'll try for a better shot)

 

 

Interesting!  You can actually see it in it's original condition:

[JH Lee]

I didn't know that these had hada??

[Bruce Pennington]

Best I can do:

 

[Bruce Pennington]

6 minutes ago, JH Lee said:

I didn't know that these had hada??

My toshigi said it resembles Nashiji, or pear.  I don't think it's a crafted hada, but just the result of the nature of the local steel that Mantetsu used.  But I'm not really knowledgeable of their steel making process, so there could be more workmanship involved than I'm stating.

[Bruce Pennington]

@IJASWORDS has this one for sale.  Wartime polish, so tough to see hada, but you can make out a bit near the tip:

 

[Stephen]

" I don't think it's a crafted hada, but just the result of the nature of the local steel that Mantetsu used. "
 

this is correct.  Bar stock will show fine grain....not hada per se

[16k]

The question being, is it bar stock? I understand that it wasn’t a simple bar but some sort of pipe. The process was probably Industrial indeed, and the "Hada" not a real one. Still, I own two and one has clearly a stronger Hada. In this (terrible) book, they show a pic of a Koa with a rather prominent Hada.

 

https://www.amazon.fr/Modern-Japanese-Swords-Beginning-Gendaito/dp/150777012X/ref=sr_1_1?__mk_fr_FR=ÅMÅŽÕÑ&dchild=1&keywords=Japanese+swords+modern&qid=1619108898&sr=8-1

[vajo]

I dont belive that there is a real hada, because the steel is not forged and folded like Tamahagane. Its a modern steel.

[lonely panet]

Well i know we all have simular information on these swords, " and i too judge kao isshin matetsu as "not" being gendai as a hole, but i cant ignore the information saying that the best were made in Japan, and these having tight ko itame hada. so all i can do is try and take a snippet of whats out there and try and observe the varing quality of hada. 

 

the hamon is void of anything i would call hataraki, so i will just focus on hada.

[IJASWORDS]

You probably would guess that in my collection of Mantetsu swords, I would have a piece that may settle the controversy. 

I have what I think is one of the earliest examples made, a Winter 1938, when production commenced, (or end of 1938 as the records show). And as most of you know, I have an example of every year including 1945. 

This sword has a DEFINITE hada, fine it maybe, but very visible. My photography is poor, but there is enough hada to show it exists.   

[lonely panet]

Oh theres something in there. Could you please persist at the photographs.   As this could add to bruces compendium of inforation. As finiding these swordd in good polish is getting hard.

 

I wish i was buying these when they were only 1000 hahaha

[PNSSHOGUN]

Beyond the very early ones the visible Hada is likely a product of the steel grain. The whole concept of the Koa Isshin was to avoid the traditional forging process and create perfectly uniform shingane and kawagane and bring them together using the rod and tube method. 

[JH Lee]

6 hours ago, PNSSHOGUN said:

Beyond the very early ones the visible Hada is likely a product of the steel grain. The whole concept of the Koa Isshin was to avoid the traditional forging process and create perfectly uniform shingane and kawagane and bring them together using the rod and tube method. 

 

Exactly.  It would seem to largely defeat the purpose of this innovative method if the outer jacket was traditionally folded steel....

[Bruce Pennington]

It's been a while since I read the history, but I remember the earliest ones were made a different way before they refined the production concepts.  I want to say '37 was the experimental year and after that they got more standardized.  But I'm talking from memory, which has often betrayed me with false info!

 

Nice one Neil!

[Bruce Pennington]

16 hours ago, IJASWORDS said:

a Winter 1938

I definitely see lines in the steel in this one Neil.  Maybe it was at the end of their experimental work.

[BenVK]

There is no Hada in the sense of a pattern created by folding steel multiple times and forge welding it together to create a billet.

It's simply the grain of the steel which depending on the polish and which stones and nugui were used, can either highlight the grain or hide it. 

As I understand it, Mantetsu swords were forged using a sophisticated taco or san mai method so the lines would be the demarcation boundaries between each different steel once it's been shaped/ground/filed to the final geometry of a Katana. 

 

 

 

[16k]

Ben, as far as the last part of your answer, I believe it is unlikely. The sleeve was a tube and the core inserted inside, then probably shaped with a power hammer, so there shouldn’t be any demarcation line.

 

Bruce, your memory is correct, although I think only the first hundred swords or so were made that way and given to the Manchurian army, probably as a publicity stunt (now, if I remember my history well too! ). Then, seeing they were onto something, they brought in a couple of real swordsmiths to teach the guys who’d done it on their own to do things properly. Then the real production started and I don’t think it varied much after that. So the Hada, imho, can come from three reasons:

- as others have mentioned, it is the natural Hada of the metal (most probably)

- said natural Hada varies according to the skill of the polisher

- we know they used an outer sleeve and inserted the lower carbon rod inside. Much is said about that rod, but unless I missed something, no text I have read discusses the manufacture of the outer sleeve, so who knows?

[lonely panet]

Genuine Guarantee First Product Mantetsu Sword Koa Isshin Mantetsu Saku Showa Akira Miharu (Building Engraved) Fu 1272 67cm Japanese Imperial Army 98-type Iron Sheath Guntō General / Sakan / Command Sword | . eBay Japan (jauce.com)

[BenVK]

On 5/1/2021 at 9:16 PM, 16k said:

Ben, as far as the last part of your answer, I believe it is unlikely. The sleeve was a tube and the core inserted inside, then probably shaped with a power hammer, so there shouldn’t be any demarcation line.

 

That's true and if all Mantetsu were manufactured the same way, high carbon steel tube and low carbon steel core, I have no explanation as to why we see that line.

The auction sword seems to have a line as well or am I mistaken?

 

[BenVK]

Ok, I think we have our answer now.

 

This from Togishi David Hofhine and photo of a Mantetsu that he polished in 2017.

 

"When finely polished the Koa Isshin Mantetsu has a nashiji-hada. This is a surface that looks something like the flesh of a sliced open pear. In this case this is a texture caused by the crystalline structure in the metal and not by a folding pattern. Some folded blades exhibit a similar pattern if the skin steel has been folded so many times that the weld lines all blend together. The hamon is primarily nioi deki suguha, but with some ko-nie along the top. No larger nie crystals. It has been reported that the Koa Isshin blade may have been tempered in water rather than oil. The composite construction of the blade allowed for the more traditional method of tempering. There is also a faint bo-utsuri about 1/4" above the hamon, visible in parts along the length of the blade. Unfortunately all of these subtle features are nearly impossible to photograph using the equipment that I have."

[Bruce Pennington]

3 hours ago, lonely panet said:

Genuine Guarantee First Product Mantetsu Sword Koa Isshin Mantetsu Saku Showa Akira Miharu (Building Engraved) Fu 1272 67cm Japanese Imperial Army 98-type Iron Sheath Guntō General / Sakan / Command Sword | . eBay Japan (jauce.com)

Thanks Hamish!

 

Ben,  this discussion is way out of my league, but that was my Mantetsu David referenced, in case you might want some photos or something.

[16k]

And a fine one, Bruce!

 

As for the faint bo-utsuri, might be one ... or not. I have two swords that show these (not Koa, but I don’t think I’ve checked for utsuri on them) and I realized they had some bo utsuri. I was a bit surprised as it was never mentioned in the descriptions, and one of those swords had been through two very competent sellers that had never mentioned an utsuri. Actually, I think those are "fake" utsuri created by a different pressure on the ji by the togishi. I’m sure someone more knowledgeable than me could confirm that.

[IJASWORDS]

There is no doubt that early Mantetsu swords exhibit HADA, fine grained it may be, but definitely there. I have some. Some of them even had wavy HAMON. The steel used in a Mantetsu sword was made in an electric furnace, not the traditional TATARA. 

An electric furnace is just another way of providing heat to the raw materials. As you all know, the iron/steel used in a sword made from TAMAHAGANE never melts, it is made into a sponge, full of impurities, and gases. Repeated heating, hammering and folding remove the un-wanted impurities.

So one could assume that at least in the early production of Mantetsu, the metallurgists were trying to reproduce a TAMAHAGANE like material, or steel sponge in the electric furnace. Using the high-speed power machine tools of the time, this sponge could be quickly turned into a many times folded homogeneous piece of steel. This folded hot steel could then be hot sheared, and the center pierced into "hockey puck" like pieces or donuts. 

So, it is commonly assumed that the softer iron core was inserted into the outer skin steel, some liken it to a rod inserted into a pipe. The longer the pipe the greater the probability of voids and discontinuities exist on forge welding, so a shorter "pipe and rod" system would guarantee no forging faults. In the sword forging process, this billet would be drawn out and lengthened by repeated heating and hammering into the sword shape. 

It is feasible that the Mantetsu steel pucks were made in Manchuria and distributed to sword makers in many localities, like boxes of donuts, but with a core of soft iron. Getting some Mantetsu swords, cutting and sectioning them would confirm their production methodology. 

So in summary, you have to assume that the above method would lend itself to mass production, ease of production, and a consistent product. The very rough sketch below is an attempt to show how a shorter pipe and core would have many production, manufacturing and quality benefits over a long thin difficult to make pipe.  

       

[16k]

Here are your cross sections:

 

[IJASWORDS]

WOW, thanks JP! I wonder if someone did polished photo micrographs of the grain structure? 

[lonely panet]

its off a mantetsu essay,  im still away from home atm. i cant post the essay thats its from

[Bruce Pennington]

Neil, the photo is from Ohmura's page: http://ohmura-study.net/998.html

[16k]

6 hours ago, IJASWORDS said:

WOW, thanks JP! I wonder if someone did polished photo micrographs of the grain structure? 

Neil, according to the author (Ohmura San) they did, but he didn’t attach the picture. However, he says the the micro photographs did prove that the welding between the shingane and Karaganda was absolutely perfect. This is why I call those swords the best that there are. They may not be traditional but with a modern technique, they succeeded in doing what the swordsmiths had tried to achieve. In a way, this is the best you can do with a sword.

[Bruce Pennington]

On 5/3/2021 at 4:31 PM, IJASWORDS said:

softer iron core was inserted into the outer skin steel,

This is from Ohmura's latest book: entitled 真説 戦う日本刀―“最高”と呼べる武器性能の探究 [True Theory, Japanese Fighting Sword]