The Shiroganeshi: Craft Techniques and History of the Metalworkers Who Make Habaki, Seppa, and Koiguchi Fittings

What Kind of Craftsman is a Shirogane-shi?

A Japanese sword does not consist solely of the blade. To sheath the blade in a saya and carry it safely, numerous metal fittings—collectively called "kodougu" (small fittings) or "kinugumi"—are necessary. Among these, a craftsman called a "shirogane-shi" specializes in making important metal fittings that are directly involved in the connection between the blade and saya.

The main metal fittings handled by the shirogane-shi are as follows:

• habaki: A fitting embedded in the hamachi (blade notch) and munemachi (spine notch) of the blade. It serves to fix the blade in the saya and is one of the most important fittings in the structure of a Japanese sword. Made from copper, silver, gold, shakudo, shibuichi, and other materials.
• seppa: A thin metal plate wedged between the habaki and tsuba. It prevents the tsuba from rattling and is used to adjust the mounting. Multiple layers are often used.
• fuchi and kashira: Metal components attached to the ends of the tsuka (handle). The fuchi is positioned on the blade side, and the kashira is on the end of the handle.

These fittings clearly divide the roles from other craftsmen such as polishers, saya makers, and tsuka-wrapping artisans. The shirogane-shi is a specialist requiring particularly precise metal working techniques. The sword maker forges the blade itself, the polisher handles the polishing, the saya maker creates the scabbard—each has an independent specialty, and a single Japanese sword is completed through the hands of multiple craftsmen. It can be said that the shirogane-shi is responsible for the "seam" that connects the blade and the mounting.

Materials Used and Their Characteristics

The metal materials used by the shirogane-shi are deeply connected to the traditional metalwork of Japanese swords.

• Copper (dou): The most widely used base material. It is easy to work with and yields diverse color tones through surface treatment. Most habaki and seppa are based on copper.
• Shakudo: An alloy of copper with a few percent gold, characterized by a distinctive deep color tone close to lacquer black. It was favored by Edo period metal workers and has good compatibility with fine carving.
• Shibuichi: An alloy of copper and silver that yields various color tones from gin-nezuiro (silver-gray) to bluish gray depending on the silver ratio. The subdued color tone is preferred and was widely used in samurai mountings.
• Gold and silver: The highest quality mountings use gold or silver. Particularly in swords made for presentation or the shogun's use, the habaki features solid gold or gold plating.

The colors of alloys like shakudo and shibuichi are not the colors of the metal itself, but rather are brought out by a process called niiro-shiage (color finishing), in which the surface is treated with chemicals. Even with the same alloy, the coloration varies subtly depending on the mixing ratio and treatment method, and this color-development technique is considered the hallmark of the shirogane-shi and metal worker's skill. Material selection is an important decision that concerns not only the aesthetic color tone but also the compatibility with the blade and the formality of the entire mounting.

The Process of Habaki Production

The core of the shirogane-shi's work lies in the production of the habaki. The process is extremely meticulous.

First, the hamachi, munemachi, moto-haba (base width), and moto-kasane (base thickness) of the blade are measured accurately, and a template is created to match the blade's cross-sectional shape. Next, tanzou (forging) is performed, in which the metal plate that will become the material is struck with a hammer to create the shape, and the inner surface that will fit snugly against the blade's cross-section is finished. Regarding the formation of the hamachi and munemachi themselves and adjustments after hardening, Hamachi and Munemachi Finishing Techniques provides detailed explanation.

Very high precision is required in finishing the inner surface. If it does not fit snugly without gaps, the blade will rattle, and conversely, if it cannot be fitted, it defeats the purpose. Adjustments are repeated in units of just 0.1mm, creating a habaki that fits perfectly to the blade.

Decorative work on the outer surface (exterior) is where the shirogane-shi's skill shines. Jimon (ground patterns) created by hammer striking, carvings such as arabesque, pine, bamboo and plum, and wave motifs made with carving tools, and zougan of gold or silver are applied. There are multiple zougan techniques, such as "nunome-zougan," in which fine fabric-like scratches are made in the base metal before gold and silver foil is hammered in, and these are chosen according to design and budget. For custom elaborate habaki, production can take several weeks.

The production of habaki typically proceeds as follows:

1. Measurement—Measuring the hamachi, munemachi, moto-haba, and moto-kasane
2. Forging—Striking the metal plate with a hammer to create the shape
3. Inner surface adjustment—Refining precision to fit snugly against the blade's cross-section
4. Outer surface decoration—Applying jimon, carving, zougan, etc.
5. Final finishing and polishing

By carefully layering each step, a habaki unique to that blade is finally completed, fitting perfectly.

The State of Modern Shirogane-shi

Modern shirogane-shi are said to number only a few dozen across the country, and the lack of successors has become a serious problem. During the Edo period, each domain had its own shirogane-shi, and many craftsmen worked in response to the demand for swords, but after the Haitou Rei (Sword Abolition Edict) of 1876, demand plummeted, and the number of craftsmen decreased dramatically.

Currently active shirogane-shi work primarily in urban areas such as Gifu, Tokyo, and Kyoto, centering on custom orders from sword makers and sword dealers rather than pre-made habaki. Prices vary greatly depending on the materials and degree of decoration, ranging from tens of thousands of yen for a simple copper habaki to hundreds of thousands of yen or more for an elaborately decorated shakudo habaki.

When requesting new work, the typical process involves first consulting with a shirogane-shi through a sword dealer or sword maker, discussing the blade's measurements and desired materials and design before beginning production. When an existing habaki is damaged or when renewing the entire mounting, the same procedure is followed to request work from a shirogane-shi. Many craftsmen respond to repair and restoration requests, and work such as tightening loose habaki or filling in damaged sections are important roles of the shirogane-shi.

Collaboration between Shirogane-shi and Sword Makers

The work of the shirogane-shi is accomplished through close collaboration with sword makers. After the sword maker completes the blade, the shirogane-shi takes the blade directly in hand to measure it and produces the habaki. The completed habaki is fitted to the blade by the sword maker or polisher, and then proceeds to the subsequent polishing stages.

This coordination among craftsmen determines the quality of the finished Japanese sword. If the shirogane-shi's technique is insufficient, it can cause the blade to rattle and lead to rust from water infiltration during polishing. As a "power behind the scenes," the shirogane-shi is an existence that quietly supports the quality of the Japanese sword.

Things to Know When Examining a Habaki

When handling a Japanese sword, the habaki receives less attention compared to the blade, but it actually contains much information.

• Differences in production period: The habaki is not necessarily made in the same period as the blade. It is not uncommon for only the habaki to be renewed or replaced at a later time over many years, meaning the blade's period and the habaki's period may differ.
• Checking the fit: A good habaki fits snugly to the blade's hamachi and munemachi without gaps and shows no rattling. Conversely, if there is looseness, it may suggest deformation of the habaki itself or poor compatibility with the blade.
• The relationship between decoration and material: Decoration varies greatly, from plain copper habaki to habaki in shakudo or shibuichi with carving and zougan. The materials and design tendencies chosen depend on the formality of the entire mounting and the historical context in which it was made.

Examining the condition and characteristics of the habaki is one way to understand how the sword has been stored and handled.

Conclusion

The shirogane-shi has long been an underappreciated craft within Japanese sword culture, but due to the high level and rarity of its technique, it is now receiving renewed attention. The meticulous craftsmanship contained in the unobtrusive habaki and seppa tells of the depth of the Japanese sword as a craft.