What are Tosa Uchihamono (cutlery)?
Tosa Uchihamono is a traditional Japanese craft produced in central and eastern Kochi Prefecture. In Tosa (Kochi Prefecture), where blacksmithing has flourished since ancient times, cutlery was produced mainly for forestry tools, and later became a major cutlery production area due to increased demand for samurai swords. Tosa percussion cutlery, produced using a unique “free forging” method not found in other production areas, is an excellent cutlery that is used mainly by people engaged in agriculture and forestry throughout Japan. Unlike Sakai knives produced in Sakai, Osaka, and Seki kitchen knives produced in Seki City, Gifu, blades produced in Kochi Prefecture are all cutlery.
Characteristic 1 of Tosa Uchihamono
Free Forging
Tosa Uchihamono are said to be “free-forging. Free forging refers to a manufacturing method that allows the dimensions and angle of the handle to be made in any way according to the use, location, and height of the blade. For example, when manufacturing sickles, the blade can be shortened for plain areas, and the angle can be increased and the handle lengthened for mountainous areas, thus making it possible to manufacture a wide variety of products in small quantities according to the intended use.
Tosa Uchihamono craftsmen can manufacture blades with only a simple order form that describes the original size and shape, and they can respond to the client’s requests. They are able to produce a high quality piece that cannot be achieved with ordinary blades that are pulled out by a press.
Feature 2 of Tosa Uchihamono
High durability and ease of care
Since Tosa Uchihamono originated from practical tools for mountain forestry and agriculture, they are characterized not only by their sharpness but also by their durability and ease of maintenance. They can maintain their excellent sharpness indefinitely, and even if they become dull, they can regain their sharpness with simple maintenance. This is applied not only to sickles and hoes, but also to household knives and outdoor knives.
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| Source: Ryokodo Online shop |
History of Tosa Uchihamono
Kochi was once called Tosa, and the traditional cutlery that originated in Tosa is called Tosa Uchihamono. This is a traditional Japanese craft that already has a long history of more than 400 years.
Kochi is blessed with good wood due to its warm and rainy climate, and a large amount of wood has been transported across the country since ancient times. Because of the need to cut down the timber, the origin of this craft is that hammered blades have been made and used for a long time. In the late Kamakura period (around 1300), a sword smith, Gorozaemon Yoshimitsu, moved from Yamato Province (present-day Nara Prefecture) and forged swords and armor, which prospered until the end of the Muromachi period. The sword smithing skills combined with the techniques of hammering knives for agriculture and forestry led to the existence of numerous blacksmith shops.
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| Source: Tosatsuboya |
The born of Tosa cutlery
Tosa Uchi-hakimono itself began in earnest during the Edo period (1603-1867), with the Genna reforms that were brought about by the financial difficulties of the Tosa Clan. At that time, the development of new rice paddies and the utilization of forest resources created a need for more blades for agriculture and forestry, and the work of blacksmiths increased rapidly. Eventually, the clan’s finances stabilized, and this reform became a major turning point for Tosa’s cutlery, which was favorably affected by an increase in the number of craftsmen, improved product quality, and expanded sales channels. Tosa (Kochi Prefecture) thus became a major production center for blacksmithing, and Tosa Uchihamono gained a high reputation throughout the country.
Although some mechanization has taken place since the Meiji era (1868-1912), skilled craftsmen continue to preserve the tradition of Tosa Uchihamono, mainly through manual labor.
Manufacturing Method and Process
1. Sumikiri (charcoal cutter)
The charcoal is split into pieces of just the right size. It is important to cut the charcoal to a certain size so that the wind can blow through the hokubo (a hot pot that heats steel or iron) with a pair of bellows and control the fire freely. It is said that it takes “three years to cut charcoal,” and it is a task that requires a great deal of skill.
2. Making steel and iron
Steel and iron, the raw materials, are made. A characteristic of Tosa Uchihamono is the process of breaking steel into iron. First, the steel is made into the cutting edge. Then, the steel is interrupted and the steel is lightly hammered between the two pieces. Boric acid is applied as an adhesive, and the steel is then placed in a fire.
3. Forge welding
This is the process of joining steel and iron together. Steel and iron are heated in a fireplace and beaten together. By sandwiching the hard steel between the flexible iron, the steel is prevented from breaking. Recently, some regions use riki zai, a material in which steel and iron are preassembled together.
4. Forging and Shaping
Forged and welded blades are heated in a fireplace. The hot, reddish blade is removed from the firebox, placed on the anvil, and beaten with a belt hammer to form the shape of the blade. The anvil is the base on which the material is struck, and the belt hammer is a belt-type mechanical hammer that rotates at high speed. Thanks to the belt hammer developed in the early Showa period (1926-1989), production has increased significantly. The fine details are shaped with an old-fashioned hammer. The forging method in which the material is heated and shaped freely with a hammer is called “free forging. This requires considerable skill.
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| Source: ANA furusato.co.jp |
5. Rough sharpening
Forged blades are sharpened with a grinder or similar tool to bring them to a uniform shape. A grinder is a machine that sharpens and polishes knives by rotating them at high speed. Rough sharpening is also called “Nama Togi.
6. Doro-nuri (mud coating)
Mud is evenly applied to the blade to improve the “hardening” process.
7. Quenching and Tempering
Quenching is an important process that determines the hardness of the blade. Blades are heated in a quenching oven at 770°C to 800°C and then rapidly cooled in water to harden them.
Since hardness alone is not enough to prevent the blade from breaking when force is applied to it, it is also necessary to make the blade more elastic. Tempering is the process of making it more elastic. Tempering” involves quenching at a low temperature of approximately 170℃. The blades are slowly heated in a tempering kettle using hot heavy oil. After “tempering,” the work is allowed to cool slowly and naturally.
8. Strain Removal
Striking with a hammer removes the overall distortion caused by the quenching and tempering process. The front and back of the blade are tapped repeatedly.
9. Edging and Finishing
The final step is the blade setting. The blade is carefully sharpened by raising the blade, sharpening it to a medium sharpness, and then attaching the small edge (koba).
While other production areas are dividing the labor, Tosa hammered cutlery, which is made through a consistent process, is gaining in reputation.
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| Source: Tosa Uchihamono-ya @yahoo shopping |
Summary
The advantages of Tosa Uchihamono are sharpness, durability, and ease of polishing. A wide variety of products are available, including sickles, hoes, household and kitchen knives, and outdoor knives for forestry, construction, and agricultural work. The manufacturing method of Tosa Uchihamono was born from the technique of making Japanese swords, a part of the samurai culture. They are called “Tosa’s free forging” because they can be manufactured using only the original size and shape of the order form, even if orders of different shapes and weights are received from all over the country. This is a feature that distinguishes Tosa Uchihamono from Shinshu Uchihamono. These characteristics have become the strength of Tosa Uchihamono, and we are constantly receiving purchases from all over the country.
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