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The Art of the Japanese Sword. Yoshindo Yoshihara
Читать онлайн.Название The Art of the Japanese Sword
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isbn 9781462909964
Автор произведения Yoshindo Yoshihara
Издательство Ingram
A hard, sharp cutting edge is required for a sword to be functional, and the complex structure of the hamon developed in response to this need for functionality. The oldest Japanese swords, which date back to approximately the fifth or sixth centuries, are straight, with narrow hamon. The older hamon were basically a straight band of brittle mar tensite steel running along the cutting edge of the blade. Although a sword made completely of brittle martensite would cut well, it would suffer a large amount of damage in use. Therefore early smiths made the body of the sword from much softer forms of steel called pearlite and ferrite. These gave the sword flexibility and toughness, so that it could bend to some extent without breaking. The design of the Japanese sword uses the particular properties of several forms of steel in different parts of the sword to make a functional, effective, and enduring weapon.
To examine a hamon in detail, the sword is aimed near or below a point light source, so that the details of the hamon can be seen by looking near the light reflected on the blade. As this only allows inspection of a small area, the sword must be moved continuously to examine the entire hamon.
As swords evolved over the centuries, they became larger and acquired curvature; the hamon also become wider and more complex. This change in the hamon developed for a very good reason. As noted above, the simple straight hamon of the earlier swords consisted of a band of hard martensite steel bonded together with a softer steel body in a straight line along the entire length of the sword. Because of the differences in the properties of these two types of steel, sometimes a single blow or strike could cause most of the narrow martensite cutting edge to separate from the body of the sword.
In response to this, swordsmiths learned to make more complex and wider hamon consisting of a series of semicircles or waves, often varying in width and height along the length of the blade. The visible boundary defining a complex hamon can range over the width of the blade from the upper part to the center, and down almost to the cutting edge. The hamon can be described as resembling a series of teeth. These “teeth” make the physical boundary between the martensite edge and softer sword body effectively much longer, and interlace the different types of steel present in the edge and body of the sword. Thus the cutting edge is bonded firmly to the body of the sword with an almost zipper-like structure. Complex hamon also limit the size of chips in the cutting edge and damage that can occur during use.
These hamon were first seen in Japanese swords from around the eleventh and twelfth centuries, and were further developed through the twelfth and thirteenth centuries during the Kamakura period (1185–1333). The modern swords we appreciate today are direct descendants of such Kamakura-period swords.
Many details can be seen when examining the hamon. The nioiguchi—the boundary defining the hamon, also called the “habuchi”—should be clear and unbroken along its length. Hamon often have extensions or projections called “ashi” going from the habuchi toward the edge of the sword, which help define the details of the hamon. Ashi usually form straight lines roughly perpendicular to the boundary of the hamon. They can be very short and almost invisible, or very prominent and long. Their presence indicates that the hamon steel is well interlaced with, and bonded to, the steel in the body of the sword.
This sword from the Kamakura period has a well-developed choji hamon.
HAMON PATTERNS
OSHIGATA AND HAMON
A swordsmith needs years of training to be able to master the extremely difficult process of making a hamon, and no two smiths carry it out in exactly the same way. In fact, a properly made complex hamon can function as a smith’s “fingerprint.” There are many smiths, or groups of smiths, whose work can be identified from their hamon alone.
Photographs of swords usually show only the outline of the hamon against the body of the sword; fine details are generally not visible. Traditional texts on Japanese swords are illustrated with oshigata, tracings of the shape of the sword with the hamon drawn in by hand in fine detail. Since the hamon is such an important aspect of a Japanese sword, the best way to present it in a text is to have a photograph of the sword alongside an oshigata of the same blade showing the hamon in detail.
In the illustration at right, a full-length photo of a tanto (dagger) is presented alongside its oshigata. The photo shows the overall shape and form of the blade, as well as the color and some details of the steel surface. However, few details of the hamon are visible beyond its general outline. The oshigata shows a thick, complex hamon boundary with an intricate shape, along with details such as ashi (lines of softer steel extending into the hamon to the cutting edge). When hamon are described or discussed, the details shown in the oshigata are used to describe the hamon and compare it to others.
Photographs of swords can show the hamon outlines, but the intricate and complex details in the hamon usually are not visible. Traditionally, an oshigata is drawn by hand on a tracing of the blade’s outline to show all the important details. Here, a photograph and oshigata of the same tanto are shown side by side. Although the photograph shows several important features of the tanto, the hamon is only visible in outline. The accompanying oshigata of the same tanto shows the hamon in detail. Presenting a photo and an oshigata together is the best way to show a sword in a publication.
THE STEEL AND STRUCTURE OF THE JAPANESE SWORD
Because the properties of the Japanese sword depend on the steel it is made from, it is helpful to learn something about the unique qualities of traditional Japanese steel. Broadly speaking, steel is a combination of iron and carbon. Japanese steel is made in a traditional Japanese-style smelter called a “tatara,” using satetsu, an iron ore that is found in sand form. The steel that comes from the tatara as a result of this process is called “tamahagane.”
When the satetsu is smelted in the tatara, the resulting steel has a high carbon content—up to 2 or 3 percent. However, to make a functional and practical sword, steel with a final carbon content of 0.6 to 0.7 percent is ideal. Thus, the swordsmith’s first task upon receiving tamahagane from the tatara is to refine the steel and reduce the carbon content to this level.
The goals of the smith are to make the steel more homogeneous, to produce a uniform carbon content, and to remove impurities in the steel. This is accomplished by hammering out the tamahagane into a thin plate, then breaking up the plate into small pieces about an inch (2–4 cm) in size. These pieces are then stacked, heated, and hammered out into a billet. The billet is then repeatedly refolded over onto itself.
Throughout the process of hammering and folding the steel, the smith reduces the carbon content by about 0.2 percent with each fold. The steel is repeatedly folded until it reaches the appropriate carbon content of 0.6 to 0.7 percent. The smith can judge the carbon content of the steel by its behavior during the folding and forging process. Once the steel reaches the proper carbon level, it is forged out into the shape of a sword, and some filing and grinding work is done to further refine the shape.
The steel has to be worked in this manner for several reasons. First, the process optimizes the carbon content. Second, it removes slag and impurities; furthermore, the steel is more homogeneous after the forging process. The original tamahagane is very inhomogeneous, and would not make a good sword. In addition,