How available was tamahagane?

[Ken-Hawaii]

In ancient times, how often was tamahagane made available, & in how many places was it made?

 

It wasn't only blades that used it, there were all types of tosogu, parts of yoroi, & many other steel pieces, so there must have been quite a lot made. During Sengoku Jidai, I assume unreparable blades were repurposed, but how did tamahagane production keep up?

[SAS]

I remember someone had done a paper on this, don't have it at hand....but given the cost of swords even then, tamahagane must have been a resource not cheaply or readily available.

[PNSSHOGUN]

I suspect much of the steel used was Oroshigane or other recycled steel if Tatara Tamahagane was expensive.

[Jacques D.]

Useful reading 

 

http://www.hitachi-metals.co.jp/e/tatara/nnp01.htm

[ROKUJURO]

My informations are:

In ancient time (KOTO) iron was produced individually by every swordsmith. Small TATARA were not difficult to build, and there was no other source for good iron. Of course, the OROSHIGANE process was used widely, and it yielded good and useful raw iron or steel, depending on the scrap metal used. This way was used by all smiths, but the bladesmiths had the best methods to purify the steel (= raffination). 

It was only after the beginning of EDO JIDAI that regional TATARA were built and used to provide an easier and constant iron source. Later, even foreign (NANBAN) iron was available. 

Interesting enough, iron production in early Europe worked in a similar way. The Celts were the first Europeans to produce iron about 800 B.C. When the process was widely understood and iron came into general use, large amounts of this metal were needed. Specialized working teams formed who built furnaces and produced iron in large quantities for the early 'production lines' in the forges. This was the beginning of the separation of iron production and processing.   

[Austus]

From "The Samurai Sword, A Handbook" by John Yumoto, p. 83:

 

"Swordsmith Yasutsugu (c. 1700), of Echizen Province, stated that he made his swords with imported steel, chiefly wootz steel from India."

 

Pretty sure he had a choice.  Just sayin'.

[Ken-Hawaii]

Austus, that's why I specified ancient times. I think it was 1555 when foreign steel became widely available.

[SAS]

Tamahagane is the best iron made out of a poor process to make it; that is why it is sorted, stacked, forge welded, cut, restacked, rewelded, etc, to achieve some homogenous steel. That was all they had in those days to work with; now it is just to maintain an art form.

[ChrisW]

SAS is correct. The process to produce tamahagane came to be because of the inherently poor quality of the source iron (black iron sands originally). The process is as we know it because it took that level of effort to produce a metal resilient enough to be used for Japanese blades. However, the metal quality of tamahagane is still relatively poor compared to other metal sources and that is why flaws are so common. However, to overcome that, they came up with folding techniques that compensated for poor metal quality.

[ROKUJURO]

Chris,

all iron producing cultures had and still have (Africa) to fold and fire-weld the raw iron to homogenize it. Only later in the development of the technique was it possible to produce a better quality which demanded less work. 

The early Vikings made wonderful Damascus blades in the 5th and 6th century. When the Franks succeeded in producing better steel, the Vikings stopped the production of Damascus and bought their swordblades from the Franks. The iron ore sources remained the same, and folding was still necessary.   

[ChrisW]

Ulfberht swords were produced using crucible steel prior to importing. As for sources, European sources are of relatively higher purity than Japanese black iron sands, it takes significantly more work to create useable steel. The process in Japan was far more intensive from start to finish. I am not arguing that they didn't fold iron to create steel; that's inherent in any pre-industrial process (except crucible steel), but I am saying that it took MUCH more work for the Japanese as their source iron was of inferior purity.

[ROKUJURO]

Chris, 

the use of Indian or Persian crucible steel in Ulfberth swordblades is just an assumption without proof. Prof. J. D. Verhoeven found that these steels have a typical content of Vanadium and Molybdenum carbides up to 0,3 %, which are not found in European blades. So it is more likely that the Frankish smiths found their own way of forging highly raffinated carbon steel without a pattern. 

This has of course not much to do with Ken's initial question so I apologize.

On the other hand this could demonstrate that the development of better techniques lead to better (= more homogenous) steel in both cultures, and the much bigger TATARA in early EDO, managed by teams of specialized workers, could produce larger amounts of iron with constant composition. But we should not forget that TAMAHAGANE, although low in phosphorous and sulphur, had a considerable content of slag which the smith could not eliminate except with hard work. The minimal impurities in the raw steel are not a big problem and do not influence the properties very much. Carbon distribution and slag elimination are the main tasks in traditional Japanese blade forging when using TAMAHAGANE.

Just a side information: Collegues of mine have gathered black iron sand on the shores of the Baltic sea and have successfully produced a lump of usable iron from it in a bloomery kiln.

[Ken-Hawaii]

Jean, I expected my question to veer into related topics, so feel free to keep adding. The fact that there were individual tatara for tosho, & how they used oroshigane to improve what iron they had (i.e., raffination), was also an eye-opener.

 

What hasn't yet been addressed was how all of the iron required during Sengoku was created. Think of the many kazu-uchimono blades we see today - they had to be made from something.

[Bugyotsuji]

From "The Samurai Sword, A Handbook" by John Yumoto, p. 83:

 

"Swordsmith Yasutsugu (c. 1700), of Echizen Province, stated that he made his swords with imported steel, chiefly wootz steel from India."

 

Pretty sure he had a choice.  Just sayin'.

Austus, 'with' imported steel may not mean exclusively with, but simply 'including' some imported steel. All you really needed was to include a bit of this in order to state proudly on the Nakago that it is made 'with' Namban tetsu.

 

Today we still see swordsmiths tossing a few old nails into their steel to give the blade a link to the past. By stretching your tamagahane with oroshigane and such ingredients, perhaps it was easier to reach one's quotient, like adding milk and soy sauce to your omelette?

[Apercus]

I did an alloy analysis of the 13th century Ichimonji tachi I have using x Ray florescence (non destructive). The test showed iron, carbon, .05% titanium, and trace amounts of silicon. The titanium was an ideal concentration for promoting thermo mechanical processing and the silicon would have increased toughness. There were no impurities detectable to five decimal places. Almost no modern steel is that pure.

[Apercus]

Sorry, forgot to sign again

Shannon

[Austus]

Tamahagane is what separates Nihonto from all other swords, even other Japanese swords.  It may not be the best steel; but it is the only one to offer up the hada and hamon activities that we all love, and some of us still struggle to understand. 

 

The fact that Japanese men were able to make this steel with such difficult raw material, using zero technology, and then make the finest blades ever seen in history, boggles the mind. And then they just happened to have the perfect rocks to be able to bring about the amazing polish that we still can't match.  Wow. 

[Ken-Hawaii]

Actually, there were significant differences among the "iron sands" that were washed out of the surrounding mountains by natural erosion, & the only "rocks" were the occasional iron meteorites.

 

I have a paper on those differences, but can't read it:

 

Effect of different iron sands on Tamahagane.pdf

 

Shannon, I'd love to correspond with you on your specific X-ray fluorescence equipment.

[SAS]

A translation of that paper would be epic.

[Ken-Hawaii]

I don't have that, Steve, but here is a chart of the properties of iron sand from different locations:

 

Koshiba - Properties of iron sand chart.pdf

 

The entire paper (in English, thank goodness) is here:

 

Koshiba - Properties of steel from iron sand.pdf

[Austus]

I couldn't find the date; but wasn't there a typhoon in the 1400s that washed away the bulk of Japan's iron sand? Was hoping someone would bring that up. Also wondering if that opened the door for Barbarian steel. If someone used a little of it just to be able to claim the ingredient; doesn't that reflect the quality of foreign steel? 

 

Another thing, does all Japanese iron sand qualify as tamahagane? What about Yasuki steel?  I will read the above document tonight. 

 

Great thread, Ken; very interesting stuff!

[SAS]

I think you are referring to the floods that destroyed the village of Osafune, where a lot of smiths were working.

[SAS]

Thanks Ken.

[Ken-Hawaii]

Austus, please don't conflate the Yoshii River flood with loss of satetsu. Water would have moved it, but probably not very far, nor would it matter, as iron sand is was & is still constantly being washed down from the mountains by erosion, So, there's no way all of it could be washed away. Yes, any iron sand can be made into tamahagane using the tatara process, & that tradition is the ONLY way to make tamahagane. So, Yasuki or other modern steels don't qualify, by definition.

 

Historically, "barbarian" steel became available around 1555, as I recall, from ballast in wrecked Portuguese ships. It's not so much that it was "better," just that it was available in comparatively-huge amounts, with almost no effort. And it's modern-day tosho who add a bit of older iron for tradition, rather than Momoyama & Shinto tosho who added a bit of namban tetsu. Geologically, Japan has virtually no mineable iron, so iron sand & the very-occasional iron meteorite were the only ways they could make their blades.

[Austus]

Thanks Ken (and Steve), for the clarification and history. So the key is the tatara, not just the sand. Then my Yasuki steel Kanezane is definitely not a traditional Nihonto. Sure wouldn't know by looking at it.

 

That document is a bit of a tough read. Funny that it ended up saying that Swedish steel is the best in the world.

[ROKUJURO]

This is an interesting subject.

First, I will answer Austus who wrote: ....'does all Japanese iron sand qualify as tamahagane?'...

No, iron sand is SATETSU (magnetite), a kind of iron ore. TAMAHAGANE (raw iron of varying purity) can be produced by direct reduction in a bloomery kiln using this ore. Different composition of the ore does not necessarily mean a different composition of the iron/steel, which will be explained later. 

Ken, I did not read the complete KOSHIBA paper, but they are talking about HSS (high speed steel), an alloy. 

...The standard composite elements accepted in the test were: C: 0.8; Cr: 4; V: 20; Mo: 1; V: 2  %. An effort was made to seek the effect of each of these elements by changing its content. At the same time, an experiment was conducted as to similar steel containing 5-25 per cent Cobalt..... 

If I understood correctly, the factory researched and used SATETSU as the main Japanese source of iron ore (but for their ongoing production they probably use other sources). However, there is a lot of difference between the iron (TAMAHAGANE) coming out of the TATARA and the iron produced in an electric kiln by complete melting. This latter method results in a higher content of accompanying elements in the iron. The TATARA process on the other side will work below the melting temperature of iron (1.538°C), so that no alloying elements present in the ore will be reduced and later found in the TAMAHAGANE. As with all modern steel production, a high efficiency factor is important for the industry. While a bloomery kiln yields roughly about 30% of iron (in relation to the percentage of iron in the ore which is calculated as 100%), a modern blast furnace turns out up to 95% because of the complete melting. The fact that the slag coming out of a bloomery kiln still contains up to 50% of iron, was used by late medieval iron makers, when they re-used the large amounts of slag left over from Celtic iron production. 

One has to differentiate between the composition of the ore and that of the TAMAHAGANE, which is relatively pure:
 
Average content in Tamahagane:  Carbon: 1.33;  Silica: 0.03;   Manganese: 0.04; Phosphorus:  0014; Sulphur:  0.006;   Chromium:  0.05, and only traces of Nickel and Copper.

It has to be said that the composition of TAMAHAGANE varies considerably even within one single TATARA process. There will be some iron with very low carbon content as well as (non-forgeable) cast iron (found near the blast holes) with a very high percentage of carbon, and a lot of steel with varying amounts of C. All these different qualities of TAMAHAGANE can be used by the swordsmith, even the cast iron. This latter will be made useable by the OROSHIGANE process.

The reason why modern TOSHO are in constant search for antique iron (old nails, anchor chains, water kettles, old agricultural tools a.s.o.) has nothing to do with nostalgic notions, but with the purity of the old iron which was produced by pre-industrial processes (TATARA). Modern steels are made with the addition of scrap iron into the furnace, and this always contains a wide range of (unwanted) alloying elements. These make the steel properties unpredictable for the TOSHO (not for the industry as they can make analyses for every batch of iron).

I will go back to your question about how large amounts of steel could have been produced in Japan's past. I do not know exactly about the situation there, but I presume that it did not differ much from Europe, although it occurred much later. In Celtic times (800 to 45 B.C.) the iron production was so high that it changed the landscape! Wide areas were completely cleared of trees because so much wood was needed to make charcoal. There was much less forest than today! In the beginning of the iron age, ore was not mined but gathered from the surface. Where there was a lot of ore in one place, big holes were dug which we can still see today! The bloomery kilns produced so much slag that hills of it were formed. As mentioned above, these slag deposits were exploited in later times when blast furnaces came up. It is probably safe to say that in Japan a comparable, non-centralized iron production similar to Europe took place besides that of the swordsmiths.

In areas with iron ore, numerous small ironworks were installed especially along rivers. Transports (wood, charcoal and ore) were easier on the waterways, and they also served as energy sources to propel bellows and power hammers. From Celtic to medieval times, iron was available mainly as ingots, so every smith had to form his stock material by himself.            

Although I have no safe knowledge of the situation in Japan, I hope that my speculation can shed some light into the past!

[SAS]

Excellent points Jean! Additionally due to the lack of alloying agents beside iron and carbon, the resulting steel formed from the tatara process is a shallow hardening steel, meaning it can be quenched in water without shattering more so than alloyed steels.

[PNSSHOGUN]

I did an alloy analysis of the 13th century Ichimonji tachi I have using x Ray florescence (non destructive). The test showed iron, carbon, .05% titanium, and trace amounts of silicon. The titanium was an ideal concentration for promoting thermo mechanical processing and the silicon would have increased toughness. There were no impurities detectable to five decimal places. Almost no modern steel is that pure.

Shannon, would it be possible to share a full copy of this analysis? It would be fascinating to most of us here. It deserves a thread of its own if you had the time.

[Ken-Hawaii]

Yes, a great writeup, Jean. Thanks! My original question was raised from reading one of Turnbull's books:

 

"As the fourteenth century gave way to the fifteenth the number of known active swordsmiths jumps to around 3,550, until with the widespread conditions of war in the Sengoku Period (conventionally dated 1467–1603), many swords were being mass-produced, with a consequent loss in artistic quality and an inevitable reduction in strength and durability. Records exist of swords being shipped in their thousands to China, with disputes arising over quality and price."

 

Wit that many active tosho, tamahagane creation must have been massive, yet I've read very little about how that happened.

[SAS]

I am sure they recycled everything they could that was iron and steel; battlefield scavengers probably did a booming business. Even broken swords could be reused, with less effort to remanufacture than raw tamahagane.