One of the most iconic Japanese national symbols is a samurai sword. The samurai sword aka a katana sword, is said to possess a samurai soul. The katana sword is known for its unrivalled engineering and flawless beauty for more than a Millennium.
The process of making a katana requires a sufficient idea of chemical metallurgy. This is because the traditional process of making a katana requires numerous steps. Numerous craftsmen would consistently work on the metal for months on end, sometimes even years to create just one blade.
The first step to making a katana is to make the steel.
The starting steel known as tamahagane, is created by smelting sand containing iron ore—iron sand—with charcoal using a large furnace made of clay called a tatara. Once the right temperature is achieved, the blacksmith has to watch the tatara, feeding charcoal and iron sand when required. This is an important step and as such the blacksmith team has to be available for at least 72 hours.
The next step requires the team to sort the steel
Once the three day smelting procedure has been completed, the blacksmith team then breaks up the clay furnace to gain access to the tamahagane. Once this is done, the steel mass is separated according to the carbon content. When low carbon steel and high carbon steel are expertly combined, the blade has the right level of toughness and razor sharp edge. If a traditionally made katana is made with just a single type of steel, the resulting blade would dull easily or be too fragile.
The third step is purifying the steel
Once the second step is done, the best tamahagane pieces are sent to an expert swordsmith that repeatedly heats, hammers, and folds the steel—sometimes up to 16 times—to integrate the carbon and iron. This also helps to push out any impurities known as slag.
The fourth step is to forge the blade
Once all the impurities have been hammered out by the swordsmith, the high carbon steel is then heated before being beaten into a long piece with a channel in between. The low carbon steel is independently heated and then hammered to a strip that fits perfectly into that channel. When this happens both metals are forged together. The hard steel is the katana’s outer shell that provides the sharp edge and the low carbon steel is the katana’s durable core.
The fifth step coats the blade
Once the katana is assembled, it will need one last firing. To achieve this, a thick mixture of charcoal and clay is placed on the katana’s dull back edge and upper sides, leaving the katana’s primary edge coated just lightly. This protects the blade while giving it the trademark wavy design known as a Hamon. Generally, the blade is fired to about 1500F or 815C.
The sixth step curves the katana
To achieve the signature curve, the katana is taken from the heat source and then plunged into water. The curve is achieved because the different steels have different speeds and degrees of contraction. Once this is done the katana is then polished and mounted on a hilt.
The Japanese sword has a long history, but it is primarily associated with the samurai. Katana have been present in the battles fought by the famous warriors of Japan for hundreds of years. We hope you've learned how to create this incredible weapon in this article.