Fabrication and Substance of
Early Iron Sukashi Tsuba in
Late Muromachi and Momoyama Periods

Early iron tsuba share material as well as functional affinities based on quality of metal, forging techniques, carbon content and presence of impurities. Tsuba were created to endure battle conditions and protect the user from grave injury. In this context, it would follow that one should be able to analyse the product from contemporaneous tsubako and katchushi and be able to make informed comparisons of technique, material and possibly even age and place of manufacture. Many scholars believe that early iron tsuba evoke an emotional response which later (Edo Period) iron tsuba fail to elicit. The limited decorative features of a tsuba in the Sengoku period captured the desperate yet hopeful mood of turbulent times, therefore, these tsuba tend to have a subtle elegance yet deeply expressive quality. Such early tsuba were utilitarian items, designed for potential use on the battlefield, and thus it reasonable to assume that their owners placed demands on the tsubako to produce a quality product. The iron quality, construction and aesthetic all seem to lose functionality, to be replaced by emphasis on artistic qualities during the Edo period.

The high degree of variance among Muromachi tsuba suggests that a potentially large number of independent artists scattered throughout the country were responsible for production. Iron ore extraction in Japan was uncentralized and resource constrained. Old records indicate that a number of ore deposits were exhausted at various times during the Muromachi period, and resource replacement was a constant issue, especially during times of civil war when the demand for iron surged. This would suggest that iron qualities varied regionally as well as through time. It is reasonable to assume that iron workers across Japan had to purchase raw materials from common sources, and as Kremers and others have suggested, that they may have been instrumental in avoiding wastage by re-using scrap materials.

The implications are that some tsuba were made as secondary products of early sword manufacturing shops, while others were made as secondary items by some armor manufacturers. As usual, modern nomenclature sways us into potentially erroneous associations. The term ko-katchushi tsuba was applied first to early iron tsuba whose sukashi motifs, robust mimi and iron character reminded people of some late Muromachi mempo and hachi. The term ko-tosho was based on observations by some scholars of metal similarities between certain early iron tsuba and the metal of sword tangs. Both terms are thus based on subjective observations, and yet they have been broadly incorporated, and likely over-used. If these terms are reflective of manufacture, then ko-tosho tsuba should be made of highly refined iron or steel that was likely folded, and associated with blade manufacture. Ko-katchushi tsuba would then be made from scrap metal used in the production of armor, which may have been folded, but generally more iron-like in feeling and appearance.

I think the safe and most reasonable approach is to recognize the tremendous variety in early iron tsuba, and that many groups or independent producers utilizing a wide range of methods were actively engaged in their production, and often participated with others with materials and ideas. This participation may well have come from groups involved in the production of armor or swords, but the actual physical or documented evidence of such an association is non-existent.

The late Muromachi and Momoyama periods are a brief but especially rewarding era in the study of Japanese sword mountings. This time of political and cultural transition gave birth to new developments in the arts. The katana and later its shorter companion sword the wakizashi were worn as a pair by men of resources, taste and influence who demanded high quality sword fittings in the latest styles. While golden splendor continued to capture many eyes, there was also appreciation of the more subdued wabi/sabi aesthetic very much influenced by tea culture. Objects that embodied these qualities were highly sought after. We will look briefly at the classic sukashi (openwork) tsuba styles of Kyoto and Owari and consider their possible mutual influences and eventual decline.

KYO-SUKASHI

 

Kyo-sukashi tsuba are openwork sword guards named for Kyoto, which was long the capital city of Japan. While Kamakura in the east had been the seat of the Shogunate and center of warrior (buke) culture for 150 years, it was in decline by the 14th C, with Kyoto becoming the heart of not only the high culture of the court (kuge), but of the buke as well. By the late Muromachi period, Kyoto recovered from the earlier disruption of urban warfare, and became the political, commercial and cultural center of Japan for the next 100 years. This combination of court and warrior influences brought an elegant and even delicate design with refined execution to the iron sword guards of the capitol. These tsuba were probably owned by fashionable, or at least status-conscious bushi of relatively high rank.

The selection of appropriate sword furniture was at least as important to the urban warriors of late 16th C Kyoto as the clothing they wore. The choice of sword fittings was not only an aesthetic decision limited by finances, but may also have been dictated by what was appropriate to one's position within the social and political warrior hierarchy. When we look at the highly decorated examples of the surviving clothing of the top military men of the late Muromachi and Momoyama period Kyoto, these Kyo-sukashi guards are subdued by comparison. The highly refined carving and sumptuous gold overlay metal work of the Ko-Kinko workers on black shakudo plate (a black-patinated alloy of copper, gold and trace metals), and perhaps Heianjo zogan guards with pictorial brass inlay on iron seem to share the aesthetic of these highly ornamented garments. Those colorful tsuba may have been what was worn by members of the upper ranks who wanted to show their wealth and position. Perhaps Kyo-sukashi guards were worn by the upper ranks with their more conservative daily clothing or on occasions when they wanted to emphasize their military role rather than show off their splendor. Or they may have been owned by a slightly lower rank for whom showy and expensive gold or brass was not appropriate or affordable. Certainly it is the iron sukashi guards that express what we think of as the ethics and philosophy of the bushi.

The iron plate that serves as the ground metal for Kyo-sukashi openwork guards is very uniformly forged and is relatively soft. These properties would be required to successfully cut out the fine sukashi designs. Any void or significant irregularity in the body of the iron would make forming continuous fine lines impossible. Extra effort in the preparation of a perfect plate would be necessary to avoid days or weeks of wasted work when a problem with the iron was uncovered in cutting the openwork. Harder iron would also make the cutting more difficult, and would likely result in a tsuba that would be too delicate and prone to breakage in actual use.

The openwork of Kyo guards is in the ji sukashi, or positive relief style. Here the ground is cut away to leave the design in iron. This is the reverse of the negative relief, or mon sukashi type of work usually seen in the so-called Ko-Tosho and Ko-Katchushi style guards. The walls of the sukashi are generally cut quite straight and with crisp edges. Fine surface carving is sometimes used, and occasionally even three-dimensional relief carving, maru bori, is seen in both very early and later examples. Decorative inlay is not used. Design motifs involving plants, mon (family crests), etc. were very popular and were produced with variations over hundreds of years.

These tsuba are usually round, although variations on mokko (lobed shapes) are seen. The diameter is moderate with most examples falling around 7.5 — 8.5 cm. The thickness is also moderate at approximately 4-5 mm. The rim is squared with some niku (slight rounding, literally meaning "meat") or is rounded. There are often signs of shaving or filing on the rims of later examples. The seppa dai (the central oval surrounding the opening for the sword tang) is narrow and elongated, as are the hitsu ana (openings for the kozuka and kogai to either side of the seppa dai). Some Muromachi period pieces will have oversized ana to accommodate the mounting of the very large kozuka or kogai that were sometimes used at the time.

OWARI and KANAYAMA

 


Owari sukashi tsuba are named for the old province of Owari near present day Nagoya. While lacking the elegance and refinement preferred in the capitol, many consider Owari tsuba to be the finest of the iron ji sukashi tsuba, best embodying the samurai aesthetic. They are strong and direct, which is seen as in accord with ideal bushi behavior. They are known for bold, symmetric designs, hard, well-forged iron with conspicuous tekkotsu (high carbon content metal showing as smooth lumps in the rim). The metal features in the sukashi designs are typically much wider than seen in Kyo tsuba. The hitsuana and seppa dai tend to be broader as well. As with Kyo-sukashi guards, these tsuba do not have metal inlay and are unsigned. We do not know the names of the makers of any of these early sukashi tsuba.

The work style in Owari is somewhat more variable than among Kyo-sukashi tsuba. We see guards that are both larger and rather small. They are generally thicker than Kyo-sukashi guards, but the thickness also shows more variability. Some thin either slightly or dramatically toward the center, others are of uniform thickness. Many in the West believe that the dished shape is the mark of a desirable Owari guard, but some of the best Owari tsuba in Japan have a uniform thickness.

 

The classic description of the Owari tsuba includes bold tekkotsu on the rim, yet many that we find today show little to no evidence of these "iron bones." Design motifs also tend to be wider ranging than in Kyo-sukashi. I imagine that within the capitol, the confines of what constituted good taste and current style were much more narrowly drawn than in the comparatively rustic Owari and Mino area. There may also have been a more diverse group of artisans producing these guards. While outside the scope of this article, other guard makers of the Owari area including Nobuiye, Yamakichibei, Hoan, etc., also tended to use very strong, dense iron showing tekkotsu. Some of these makers went even further in simplifying decoration and following "tea taste."

Where Kyo-sukashi tsuba depend mostly on the merits of the composition and cutting of the design, Owari area work often relies more on the character of the iron itself. Where Kyo iron is homogenous and smoothly finished, Owari guards are often given a hammered or in the case of Kanayama, a melted finish with much modeling of the iron from prominent tekkotsu. This harder, less homogenous iron probably required that wider and less delicate lines be cut. Kanayama guards mark another step toward further simplification of the sukashi pattern and elaboration of the qualities of the iron itself. The raw material and technology are completely interwoven with aesthetic solutions.

Kanayama tsuba were produced from early Muromachi to Momoyama period (1333-1603) and beyond. Kanayama guards are also from the Owari area, but have a number of distinguishing characteristics. Most Kanayama tsuba are relatively small but thick, and have simple, often difficult-to-interpret designs. The surface texture of the iron is usually highly modulated and shows pronounced tekkotsu. Some of these tsuba appear to have been finished by slightly melting the surface after forging and shaping. This brings out tekkotsu from the high carbon inclusions in the iron. The surfaces resemble the high-fired glazes of the Mino and Seto ceramic kilns in the area. Some of the older references identify Kyoto as the origin of Kanayama tsuba, but Akiyama's work and most subsequent research connects them with the Owari sukashi style and a place of origin in Owari or perhaps Mino. Some early texts refer to Kanayama tsuba as very thin, and being too weak, due to excessive open work, to be functional guards. We have to wonder whether the name Kanayama was used in reference to a different type of tsuba at one time. What we usually call Kanayama today are among the strongest and most reliable sukashi guards. It is interesting the Kanayama iron does not seem to be as hard as Owari, but the finished product shows an equal or greater intensity of tekkotsu. This may be due to the heat treatment process.

ADOPTION and CROSS-FERTILIZATION

We see some tsuba of this period that have characteristics of both Kyoto and Owari sukashi. These guards can have the bold, symmetrical designs associated with the warrior aesthetic of Owari, but are instead executed in the softer iron of Kyoto. Some simply look like more delicate versions of Owari tsuba. Other designs use fine sukashi cutting like Kyo, but are finished with more texture and activity to the iron surface than the typical smooth finish of Kyoto work. Are these Owari style guards made in Kyoto, or was the Kyo influence reaching the tsubako (guard makers) of the country towns? Of course the fashions that arise in major urban centers usually later spread to the outlying areas, influencing their sense of style. But was that the case here? It seems possible that some of these Kyo-Owari style guards were also produced in the capitol, filling the new demand for the "rustic wabi/sabi aesthetic found in country work.

KO-SHOAMI

Ko-Shoami share some characteristics of the Owari tsuba, they also show some Kyoto characteristics (more refined). The iron of the Ko-Shoami tsuba is more homogeneous than the iron of Owari or Kanayama tsuba. There are some iron bones but not as prominent as the other types discussed above. One defining trait that is hard to recognize is that Ko-Shoami tsuba show motion in the sukashi design. If one looks at the design what initially looks symmetrical often is not truly symmetrical but shows a 'twist'. The twist idea is really that the design shows motion. There is intentional asymmetry. Early pieces are exceptionally good at showing this motion effect.

The name Shoami is often translated as "one who is skilled in the arts." This term appears to have been in use at the time of the origin of the Ko-Shoami tsuba in the Muromachi period. The use of the ami kanji implies more than mere skill; it also has religious connotations in relation with Amida Buddha and association with high warrior culture. We know of many other "ami" serving the shogun and other high status military men of Kyoto — the Honami sword appraisers, Kanami and Zeami in No drama, Noami, Geiami and Soami in painting and the Koami in lacquer.

It may be that the Shoami also served in this dual role for high buke customers. They may have fulfilled orders both by creating fittings themselves and by subcontracting work out to other makers. If this were the case, it would help explain why the name Shoami figures so prominently in the records of the time. Robert Haynes comments "Dr. Torigoye in his studies of various daimyo (warlord) records, found that the only family name mentioned, in most cases was the Shoami." Were the Shoami acting as middlemen, between the high buke customers and the makers Kyo, Owari, Kanayama and other styles of tsuba? There is nothing about the quality or originality of the work of those other makers that is second to the Shoami, but it is possible that the Shoami held a position above them.

Another idea that has been advanced is that they were all simply known as Shoami despite the differences in their characteristics that we base our connoisseurship on today. However, if these were different groups working in different places, calling them all by the same name would only cause confusion, unless there was some common organization or head that was the contact point in Kyoto as hypothesized above. On the other hand, if they were the only group, as some believe, could they really have produced such a diverse body of work? This idea of everything being Shoami doesn't seem to hold much promise.

Yet another possibility is that the Shoami were the only independent group of makers and so were the only ones that received mention. The makers of the Kyo-sukashi tsuba may have been retainers that were simply taken for granted as their output was already secured with a yearly stipend. Owari tsuba and other goods from that region would have been brought to the capitol by merchants, which were beneath the notice of the daimyo or Shogunate. Within this idea, the Shoami may well have held a position like the Koami, or may have been strictly fitting makers and not middlemen. Unfortunately, we have no evidence that allows us to advance a certain theory.

The earliest Shoami tsuba, called Ko-Shoami (ko meaning old, pre-Edo period), were unsigned, like the other sukashi tsuba of the time. In addition to the iron Ko-Shoami ji sukashi guards, there are both pierced and unpierced plates with colored metal inlay, particularly inlay applied with the nunome zogan technique (a method of attaching patterns in gold or silver foil to a crosshatched surface on the iron plate). The Ko Shoami are believed to have originated in the Kyoto area. The later examples with rich gold nunome inlay certainly seem consistent with Kyoto tastes and resources. However, the early examples of Ko Shoami sukashi tsuba show characteristics of Owari area tsuba in their iron and the handling of the surface. The designs are usually less rigid than what we see in Owari and the plates are generally thinner. In many ways they seem to be in the middle ground between Kyo and Owari sukashi, but with designs of their own.

The exact nature of Ko-Shoami guards remains elusive and seems to float near the boarders of the Kyo and Owari styles. Why was Shoami the one name that appears in the written records of the time? Who were the makers and what were the connections between them and other contemporary fittings artisans? Unfortunately we do not know any of their names and it seems unlikely that any documents will emerge to tell us. While we can separate these guards into Kyo, Owari, Kanayama and Shoami types based on the characteristics of their iron, finishing and style of decoration, we cannot be certain of who actually made a given piece.

DECLINE in EDO PERIOD

The move of the capitol to Edo, the establishment of a stable society, improved transportation and the movement of goods and people quickly changed swords and fittings in many ways. The pure Kyo-Sukashi and Owari-Sukashi styles continued into the Edo period, but the exciting quality of Owari iron was quickly lost and the strength of the openwork designs faded. The best of the original Owari qualities disappeared, but various makers continued to make different style tsuba in Owari.

Kyo iron also diminished in quality during early Edo. Many of the Kyo-Sukashi style tsuba after that time were probably not made in Kyoto. While the Kyo style was preserved longer than that of Owari, they became shadows of the earlier tsuba, following conventional designs on mass-produced iron plate. There was somewhat of a revival of style in the Daigoro work of the late Edo period.

Kanayama tsuba seem to have died out rather abruptly in the early Edo period. Some have speculated that perhaps a particular type or source of iron ore that lent itself to the production of spectacular tekkotsu may have been exhausted. A few Kanayama influenced designs can still be seen by the later part of early Edo, but the type of the iron is not the same. The Kanayama style, along with Yamakichibei, Yagyu and other Owari area products, were revived in the late Edo period when numerous reproductions were made by the Norisuke and others. These copies are still confusing collectors today.

The Shoami of course were a great success story. They spread across Japan and we have a long list of regional names for the branches that they established. The early Ko-Shoami sukashi style did not simply continue without modification, though. The sukashi guards were decorated with gold nunome and began to show a lot of carving in the round: Many styles of carved and inlayed pictorial designs were done on iron and soft metal plates as well. Ultimately, even the Shoami schools were eclipsed by other groups and styles and were finally reduced to mass production of low quality guards in Mito and Aizu.

There is still disagreement about the dating of the earliest Kyo-Sukashi, Owari, Kanayama and Ko-Shoami guards. Traditional dates were placed around the middle to late Muromachi period. The late Sasano-sensei's many years of research led him to establish the earliest guards of each of these groups at the beginning of the Muromachi period. The current consensus in Japan seems to be toward moving the dates of origin up as far as the 16th C (see for example the Sano museum exhibition catalog Sukashi Tsuba Kofun to Edo Jidai). Whatever beginning date is correct, a remarkable depth and breadth of expression was developed over a relatively brief but fascinating period. We can only hope to share in some of what there is to know on the subject and to look forward to future research.



UNDERSTANDING TEKKOTSU (Iron Bones)

Perhaps the two most important and characteristic, and yet most poorly understood aspects of early tsuba manufacturing techniques are 1) folding of the metal and 2) heterogeneous carbon distribution. As collectors we look for these features manifested as fold or weld lines and various forms of tekkotsu (iron bones) respectively. Tekkotsu may be defined as segregated areas of high carbon content, formed as a result of a process of successive episodes of heating, folding and hammering of an iron plate. Generally speaking, increasing the carbon content in iron, results in decreased ductility. Thus, a localized area of high carbon content (tekkotsu) effectively forms a localized hard spot. These localized areas of decreased ductility tend to interfere with crack propogation by deflecting or blunting the crack. These attributes are often used as indicators to distinguish older and higher quality tsuba, however, many collectors fail to understand just why this is so.

From a mechanical perspective, both folding and carbon distribution alter the stress behavior of the iron tsuba in ways which increase resistance to impact. Folding iron greatly increases resistance to ballistic and notch-impacts by dissipating the impact energy from effectively a point or line source to a greater surface area provided through successive planes of laminated material that tend to shear or delaminate rather than fracture. The combination of the laminated plate of a tsuba, with heterogeneous carbon is thus a effective crack arrestor. Evidence of this is seen in the thinness of the earliest iron tsuba. Perhaps the tendency to thicken the rim and/or plate of a tsuba toward the end of the Muromachi period is attributable to attempts to find balance between tsuba integrity and the call for increasing amounts of artistic design elements via sukashi in a tsuba meant for the battle field.

Another consideration in understanding early iron tsuba is material is the tsuba composed of high carbon steel or iron, and what are the implications of this distinction? Kremers (1994) briefly addressed the question of steel vs. iron, pointing out the main problems as being the difficulty in distinguishing between the materials in an old tsuba, and in identifying the possible source of the materials employed in the manufacture.

Iron bones are to tsuba (iron tsuba) as kinsugi, sunagashi, and other activities are to sword blades. They are simply something to be enjoyed when appreciating a fine iron tsuba. If they are done well (as one would expect from a fine tsubasmith), they will bring you back time and again to that tsuba, giving great pleasure to you.
 
Sasano says, "In forging, mixtures of irons of different qualities produce distinct texture variations that are visible in the flat bodies and rims of guards. These variations are categorized according to appearance into three classes: fine granular; coarse granular; and linear (frequently together with hammer marks)."

 
 


 

Coarse granular.
This type is the most easily recognized since they will seem like "lumps" within the surface or along the rim of good, well-forged and rustic looking tsuba. In fact they are lumps, the iron of a different quality as mentioned above by sasano. They usually take on a softly polished look since they do stand up above the rest of the surface of the tsuba.
 
Fine granular.
This is identical to coarse granular except the lumps are much smaller and will give a more subtle, less rustic appearance.
 
Linear bones.
Linear tekkotsu are just that, and they seem to appear most often along the rim of well-forged iron tsuba. It seems that linear tekkotsu are a result of the folding process in which the different iron is put into the linear folds of the tsuba. These too will appear softly rubbed since they are slightly raised and of a harder iron than the rest of the plate.
 

 
 




What causes natural tekkotsu?
 
With the mixture of soft and hard steel of the tsuba, as it rubs against the apparel of the samurai, the softer steel wears away and leaves the harder steel behind. Therefore you get bumps, ridges, and ribs of hard steel - tekkotsu! A once smooth rim now is uneven but left behind is clear evidence that this tsuba saw much time at the side of a samurai. The smooth skin now has the hard steel ribs, the "iron bones," showing!

The literal Japanese-to-English translation of the description of some tekkotsu uses the word "powerful." Perhaps it is an emotional reaction to the tekkotsu. It is the impression this wonderful tekkotsu has on the examiner. But maybe some tekkotsu is called "powerful" because a large quantity of tekkotsu means the tsuba is strong. It means it had more hard steel in comparison with soft steel. It served its wearer well.



I will acknowledge the following who contributed to the above educational text:
Robert E. Haynes (my friend and teacher), Jim Gilbert, Boris Markhasin, Allen Harvie, Dean Hartley, and those I apologize for forgetting.

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