The Katana sword is a Japanese blade that has a long, curved shape and a hilt. It is commonly associated with Samurai warriors, but it has also been used by many other martial arts. The katana’s curved form means that it can be drawn and then hit with a single movement. It is also easy to hold and handle.
To make a katana, smiths use different folded layered steels with varying carbon concentrations. These are heated to high temperatures, but never molten. This process removes impurities from the metal and creates a blade with an exceptionally hard edge and softer spine. The softer core also allows the blade to absorb shock and retain its strength after being struck.
After the blade has been forged, it undergoes a crucial heat treatment process called yaki-ire. The smith applies a clay slurry to the blade, with thicker layers on the body and spine of the sword and thinner ones along the edge. The sword is then heated and quenched in water, which separates the two different densities into distinct zones within the blade. The harder edge is then sharpened, and the softer spine is made resilient.
During the Muromachi period, when large-scale warfare was introduced to Japan, the katana became shorter and more curved. The shape was designed to suit the fighting style of this era, and it was at this point that some of the most famous bladesmiths emerged. The katana’s role changed again during the Edo period, and it became a symbol of Japan’s culture, as well as its military history. Today, traditional sword smithing is recognized as an intangible cultural heritage by the government of Japan and supported financially. The keywords I will use are