Japanese Sword Polishing: The Craft and Why It Matters

The Japanese sword is renowned for the artistic characteristics of its blade, which can be fully appreciated once a skilled polisher has meticulously polished it. The sword polisher brings out the beauty of the blade, refining its shape, colour and texture. Traditional schools of polishing have even developed techniques to bring out the sword's finest qualities.

Let us look at the importance of sword polishing, the characteristics of a good polish and the Japanese techniques of this art.

Why is polishing essential for Japanese swords?

Traditional Japanese swords, or nihonto, show artistic details on the surface of the blade. These include the hamon (temper line pattern), the jihada (grain pattern) and the jigane (steel surface). Polishing brings out all of these features, which are necessary for the aesthetic appreciation of Japanese blades. A polished blade also makes it possible to identify the swordsmith or school that made it and to carry out a close examination when the sword is appraised.

Throughout history, the Japanese sword has been a remarkable blade, used both in duels and in the field. It has a very long history and has continually evolved in response to historical events and the needs of the age.

A Japanese blade is well polished when all of its artistic characteristics are clearly visible. By contrast, a poorly polished blade may have an apparently clean surface, but its details remain hidden, making close examination impossible.

Polishing also improves the functionality and performance of a blade. A polisher gives the blade a keen cutting edge, whether it is newly made or needs repair for nicks or distortions. In fact, several flaws in the blade's surface, as long as they are not fatal, can be corrected by polishing. Polishing also gives the blade a reflective, mirror-like finish. However, some antique swords remain cloudy even when polished.

Types of finishing polish

Traditionally made Japanese blades undergo meticulous polishing methods. The two main types of finish are hadori and sashikomi.

Hadori

The process of whitening the hamon (temper line pattern) is called hadori. Many sword collectors today favour a pronounced hamon, and hadori enhances its visibility and brilliance. It creates a greater contrast between the white edge and the dark body of the blade, which further accentuates its visual appeal.

Hadori (刃取り) is also known as kesho (化粧), which means "cosmetic". It is relatively recent, though it does not date from the Meiji era. In general, it is the polisher who decides how closely to follow the habuchi or nioiguchi, that is, the boundary that defines the hamon. Unfortunately, the whitening effect of hadori masks these finer details of the steel.

Many sword connoisseurs, more interested in the metalwork and craftsmanship, sometimes forgo the hadori process when having a blade polished. Yet if hadori is carried out correctly, all the details of the hamon, including its habuchi and its activities (hataraki), can be visible under close examination.

Sashikomi

Sashikomi (差し込み) is the traditional form of polishing from before hadori became popular. However, its effects can appear a little dull. It shows the details of the entire blade but does not particularly emphasise the hamon against the body of the blade. Instead, it shows the hamon with all the details of its structure.

Japanese sword polishing techniques

Polishing a newly made Japanese blade is as complex as making it. It comprises two main processes: foundation polishing (shitaji togi) and finishing polish (shiage togi). Throughout these stages, traditional polishing stones, coarser or finer, shape and refine the blade.

Shitaji togi: the foundation polish

During the shitaji togi stage, the polisher shapes the blade, refines it and prepares the surfaces for the final polish. The polishing stones used are the arato, kongoto, binsui, kaisei, chu-nagura, koma-nagura, suita, uchigumori-hato and uchigumori-jito.

The aim of the foundation polish is to make the surfaces of the blade even, in particular by keeping the ridge line (shinogi) correctly formed. This process also sharpens the cutting edge and reveals the hamon (temper line pattern) and the jihada (grain pattern).

Shiage togi: the final polish

During the shiage togi stage, the polisher improves the colour and appearance of the blade's surface. The aim is to make the artistic details more visible, to define a sharp point (kissaki) and to achieve a mirror finish. To do this, the polisher uses fine chips of polishing stone, covered with paper and lacquer.

Using hazuya stones

Hazuya stones remove the scratches, marks or imperfections left by the previous polishing stage. They are used on the cutting edge and the hamon, excluding the area of the point. At this stage, the surface of the blade should be even and smooth.

Using jizuya stones

Jizuya stones enhance the appearance of the blade's surface and bring out the jihada (grain pattern). This process helps give the blade a darker, more distinct overall appearance.

Applying nugui solution

A mixture of iron oxide and clove oil, called nugui, is applied to the surface of the blade. It gives the steel a dark, non-reflective finish. However, too much nugui blackens the metal. The darker surface improves the visibility of the jihada and other intricate details.

Whitening the hamon

A hadori stone whitens the hamon (temper line pattern) and improves its visibility, giving it strong contrast with the body of the blade.

Defining the point

The point (kissaki) of the blade is the last part to be polished. It involves two processes: sujikiri and narume. The sujikiri process creates the yokote line, the line that separates the point from the body of the blade. The narume process, for its part, polishes the area of the point, ensuring the clarity of the boshi (the hamon pattern in the area of the point).

Burnishing the blade surface

The burnishing process, known as migaki, creates a mirror finish on the mune (back surface) and the shinogi-ji (the surface above the shinogi ridge line). It is carried out using a burnishing needle (migaki-bo) and a spatula (migaki-bera).

History of Japanese sword polishing

In the earliest times, Japanese swordsmiths did not merely make the blades; they also polished them in order to obtain sharp cutting edges and refine their final shape. Over time, however, a specialisation in sword polishing emerged, leading to distinct craftsmen devoted exclusively to this art.

Kamakura period (1192–1333)

During the Kamakura period, sword polishers began to work independently of swordsmiths. Their skills progressed to the point where they could polish blades effectively, revealing the artistic details of their surface.

Muromachi period (1338–1573)

Professional sword appraisers began to appear in Japan. Samurai swords were increasingly valued not only for their practical qualities as swords but also for their artistic qualities. As a result, polishing techniques and expertise continued to develop during this period.

Edo period (1603–1867)

Polishing and appraisal of swords had become highly sought after by the ruling shoguns and daimyo. Demand for Japanese swords was driven not only by their practicality but also by their status as symbols of power, prestige and refined craftsmanship.

Facts about Japanese sword polishing

Japanese sword polishing, known as togi, is essential to the sword-making process. A sword polisher who refines a Japanese blade is called a togishi. Sword polishers bring out the beauty of a blade and highlight the sword's important points of appreciation. They also refine the shape of the blade and sharpen the cutting edges.

After forging the steel into a blade, the swordsmith hands it to the polisher to be refined.

The polisher first refines the geometry of the blade, including its lines and surfaces. The blade is then sent to a habaki maker, who fits the blade collar to the tang. It then passes to a scabbard (saya) maker, who supplies a scabbard made to the exact dimensions of the blade. Finally, the blade returns to the polisher for the final polish, which brings out the jihada (grain patterns) and hamon (temper line patterns).

Japanese blades that have been polished many times are said to be tired.

Swords can be described as thin or thick, the thickness of the blade being called kasane. Blades that have kept their original thickness are often described as "healthy" or "robust". By contrast, blades that have been through several polishing sessions are considered "tired" because of the reduction in thickness caused by the removal of metal during the polishing process.

Some flaws in the blade's surface can be corrected by polishing.

A sword polisher can remove certain flaws on a blade if they are not considered fatal. For example, a polisher can reshape the kissaki (the point) if its tip is broken, provided the hamon remains intact. Unfortunately, when the hamon is interrupted, the polisher cannot repair the damage. Such flaws are fatal and are called kizu; they reduce the value of a Japanese blade.

Polishing stones are the traditional, principal tools used to polish swords.

In Japan, polishing stones are quarried from the mountains of Kyoto. They have an extraordinarily fine grain and are extremely expensive. In ancient times, polishing stones were precious gifts presented by feudal lords.

Polishing stones play a crucial role in revealing the full potential of the surface of a blade's steel, called the jigane. Different stones interact differently with the steel, and each blade needs a slightly different stone to show off its beauty.

The apprenticeship of a sword polisher can last up to ten years.

Making a Japanese sword requires the skills of several highly specialised craftsmen. Sword polishers may be apprenticed for 5 to 10 years, depending on the school, while swordsmiths are apprenticed for 5 to 7 years before obtaining their licence. Similarly, the habaki maker (blade collar maker) trains for up to 8 years before being able to work independently. Their work is therefore highly honoured and sought after.