Japanese Sword Polishing: The Complete Guide

What is the purpose of polishing Japanese swords, and how does it differ from sharpening other blades?

There is no precise way of knowing the origins and development of the art of polishing Japanese swords, because of the nature of a process of repeated sharpening over time.

However, a description of Japanese sword polishing can be found in the Engishiki, a mid-Heian-period code describing the court's annual ceremonies, and two "togishi" (polishers) are mentioned in the Kanchiin Honmeizukushi, a Kamakura-period book on swords. This suggests that polishing has been part of the making of Japanese swords since ancient times and that there were craftsmen who specialised in it.

The purpose of sharpening knives other than Japanese swords, such as those used in daily life, is to restore or improve their cutting edge. Japanese swords, which have a long history of use in battle, were also sharpened in order to show their full ability to pierce and cut.

The purpose of sword polishing does not stop there. After the Meiji period (1868-1912), when samurai society came to an end, Japanese swords came to be appreciated as "works of art" rather than as tools of the battlefield. In other words, not only the sword's robustness in terms of performance but also the beauty of its appearance came to be sought and appreciated.

The various elements that make up the beauty of a Japanese sword include many subtle things that cannot be seen at first glance. One of the aims of polishing a Japanese sword is to bring out as many of these features as possible.

Practical aspects of polishing Japanese swords

What is the history of Japanese sword polishing up to today?

The art of polishing Japanese swords is said to have been handed down to the present day largely thanks to the achievements of the Honami family, whose founder was Honami Myohon, who served Ashikaga Takauji as a Dobo-shu (a person who served alongside the shogun or feudal lord and was responsible for artistic and miscellaneous affairs) during the Northern and Southern Courts period.

The Hon'ami family has been involved in the family business of caring for, polishing and appraising swords for generations. After the Ashikaga family, it served the Toyotomi and Tokugawa families, and was responsible for various tasks relating to the swords owned by the shoguns.

The Hon'ami family was held in high regard in the field of polishing. However, in the Meiji era (1868-1912), the Soke and some of their affiliated families ceased to exist. On the other hand, some of the branch families survived, and the present Hon'ami family traces back to a branch family whose founder was Koui, the third son of Koushin, the seventh head of the Soke family.

In addition to Kouyi, who became the eighth head of the Soke, Kouzou had several brothers, one of whom, Kouji, also established a branch of the family. Koji was originally the son-in-law of the childless Kōshin, but later left the soke himself when Kōshin had a son of his own. At that time, the country was in the Sengoku period.

In the early Edo period, the second head of the Hon'ami family, Hon'ami Koetsu, who was arguably the most eminent member of the family, came from the Koji line.

Koetsu was not only engaged in the family sword business but also showed his talent in various artistic fields, including calligraphy, ceramics, the tea ceremony and lacquerware, to the point of being described as a "complete artist". This may be because the Japanese sword is itself a complete art form that brings together a wide range of craft techniques, including metalwork, woodwork, maki-e and carving, as well as swordsmithing, and his aesthetic sense for craftsmanship developed naturally from an early age.

The Hon'ami family of the Kouyi line is a group of masters in the modern and contemporary world of Japanese sword polishing. Let us now look at some of the leading polishers among them.

Honami Heijuro Narushige

His real name was Eguchi Kurajiro. He was the adopted son of Naonojo Nariou, the 14th head of the family, and a master craftsman of the Meiji era who followed in his footsteps. He invented a new technique, popularly called "cosmetic polishing", based on the traditional insertion-style polishing practised until the Edo period.

As the term suggests, this technique is used to give the pattern of a Japanese sword's blade a beautiful white appearance, and it has become the most widespread technique today. He died in 1882 (Meiji 15), aged 55.

Honami Rimga

His real family name was Yamamoto. He was a nephew of Seiō but was adopted by Hon'ami Heijūrō Narushige and took the reins of the family. At first he was called Honami Naruyoshi, but in 1911 his favourite sword master, Sugiyama Shigemaru, gave him the name Rimga.
He died in 1927, aged 68.

Honami Koureki

Born in 1879 (Meiji 12), the son of "Kawaguchi Magotaro [Kinmei]" (川口孫太郎), who served in the Ueno Maebashi clan (Kozuke Maebashi domain: today's city of Maebashi, Gunma Prefecture). His real name was Sadakichi. At the age of 18, while studying under Hon'ami Rimga during the Seizen period, he succeeded to the Koga name, which descended from the Komi line that had been broken off, under the care of Hon'ami Rimga, and took the name Hon'ami Mitsuyoshi. Hon'ami Mitsuho's polishing skills were of a high level and recognised by his masters.

In 1914, he published a book entitled "Japanese Swords" in order to spread more widely the methods of polishing and grading Japanese swords, which until then had been considered a secret tradition. In 1955, at the age of 77, Hon'ami Mitsuhisa published his famous work "The Rules and Characteristics of Japanese Swords", which still enjoys a well-established reputation as an introductory book on sword appraisal, and he died the same year.

The Japanese sword polishing procedure

The procedure for polishing Japanese swords can be divided into two main stages: foundation polishing and finishing polishing. Before that, however, there is also a process called "forge pressing / rough grinding", which is carried out by the swordsmith who produced the Japanese sword.

The main purpose of polishing a Japanese sword is to shape the sword and bring out its beauty to the fullest. Therefore, to make sure that the blade pattern, which is the most important criterion for the beauty of a Japanese sword, is clearly visible, the sword is ground with about 7 types of whetstone of different grits, moving in turn from the coarsest stones to the finest.

This section gives a step-by-step explanation of the process, from forge pressing through foundation polishing to the final stage of Japanese sword polishing, the finishing polish.

Forge pressing / rough grinding

This process is carried out to shape the hardened sword blade before the foundation polishing stage. The shape and lines of the blade are determined, and the swordsmith finishes the blade himself in order to check the final finish before sending it to the polisher.

Polishing with stones

Iyoto

[Stone grit size] 120-220.

The coarsest stone, used to remove red rust and to grind a sword blade that has been hammered (rough-finished by the swordsmith) in order to determine its overall shape.

In later work, the blade is ground repeatedly to obtain a more refined shape while keeping the "nikuoki" (the thickness of the blade excluding the shinogi-ji) determined at this stage.

Binsuido

[Stone grit size] about 400

A whetstone used to remove the scratches left by the iyoto and to adjust the details of a sword blade that is out of shape.

The basic method is the "kiri" polishing method, in which the stone is placed horizontally against the sword blade.

Another important process is polishing the blade so that its shape matches the era in which it was made.

Kaiseido

[Stone grit size] about 800

A whetstone used to remove the scratches left by the binsui stone. It is not applied to the kissaki (point) because it has a strong grinding effect and there is a risk of removing too much of the steel.

This work requires special care to reduce the amount of grinding. Here the blade is ground so that the scratches of the stone form an angle with the blade, called "sujikai".

Chū nagurato

[Stone grit size] No. 1,000-1,500.

Work with this stone is done in two stages: first, the blade is ground "osujikai" (at a more oblique angle than sujikai) in order to remove the scratches left by the binsui stone.

When the binsui scratches have been almost entirely removed, the next stage is to polish the blade using a method called "tatsu-tsuki" (literally, striking the blade with a tatsu). This is a method of grinding the blade vertically along its length, with the scratches of the stone aligned neatly without any irregularity.

When sword mountings such as scabbards are being made, the sword is sent to a specialist craftsman at this stage.

Hosonagurato

[Stone grit size] No. 2,000.

It is used to polish the blade in the same way as the Nakamagura stone, using the tatsu, while erasing the scratches left by the Nakamagura stone. This is the last step of the foundation polishing process, in which the pattern and surface of the blade gradually become visible. Foundation polishing is therefore an extremely important process that determines the final result of the blade.

The last stage is called jiji polishing, and it is a very important process because it determines the final shape of the blade.

Finishing

The purpose of foundation polishing is to determine the shape of the sword blade and bring out the blade's original characteristics. Finishing polish perfects the appearance of the blade further so that it can be appreciated. Whereas the only tool used for foundation polishing is a whetstone, albeit of varying grits, the finishing process is different and uses a variety of tools.

Lustre

This process is used to polish the blade, using two types of stone, but differs from foundation polishing in the way it is carried out. The first is a delicate process in which the sword is polished by moving a small stone on the fingertip, while the second is done by moving the sword.

Ha tsuya

The blade is polished using a 1 cm square of uchigumori-do, torn into fine strips of 0.5 mm, and a hazuya-do, which is lined with Yoshino paper and lacquered.

The process involves placing the stone on the tip of the thumb and pushing and sliding it over the blade while applying uchigumori-do slurry to the blade to help the stone glide.

The blade is polished to remove the scratches of the grinding stone up to the foundation polish, and the burnished edge is then polished to obtain a pear-skin finish. This process is used to bring out the nie and nioi that make up the blade's pattern.

Jidzuya

A polishing stone called "Narutaki-do", less than 1 mm thick, is used. There are two types of stone: "hari-ji", which is covered with Japanese paper, and "kuraki-ji", which is not covered but crushed into small pieces with the tip of a fingernail.

Polishers place about ten grains on the blade and rub them upwards, holding them in place with the thumb. The purpose of ji-tsuya is to bring out all aspects of the base iron, such as the skin pattern and the jiobu. It is the last stage of the polishing process using a stone and is also the most important stage of the finishing process.

Migaki

After the stone work on the blade is complete, the next process, which varies slightly from school to school, is burnishing (migaki), which mainly consists of polishing and burnishing the shinogi-ji and the mune of the sword blade using a spatula and a burnishing rod.

Before burnishing, the blade is coated with "tsunoko", made from burnt deer antler reduced to powder, in order to remove oil from the blade, and then "ibota", a kind of polishing powder, is applied to the area to be burnished to help the steel burnishing rod glide.

The sword is then burnished with the rod, but the burnishing must not completely destroy the forged surface of the shinogi-ji and the mune. It must give a mirror shine while retaining their patterns.

Around the metal collar and the tip of the mune, a small area is left lightly polished, and a line called "nagashi" is drawn on the metal with the burnishing rod. This nagashi is a kind of signature of the polisher. The number of nagashi and the way they are drawn vary from polisher to polisher and from school to school.