Katana is a samurai sword with a distinctive deep curve. During Japan’s feudal period, it was an essential tool for the warrior to carry into battle. It was a weapon that could cut through anything and was also used as a ceremonial mercy sword during the ritualistic Japanese suicide called seppuku.
The forging technique of katana sought to achieve three highly desirable qualities, not to break, not to bend and a razor sharp blade. Achieving these qualities was a very difficult task as the metal needed to be both tough and flexible. This was accomplished by using a combination of steels with different densities. The blade is made from a traditional tamahagane, which is a steel with varying levels of carbon. The hard, high-carbon steel forms the sword’s outer shell and deadly blade, while the softer, low-carbon steel forms the katana’s spine and shock absorber. This combination is achieved through a process of heat and cooling known as differential quenching.
A similar technique is used for the tsuka. Traditionally the samegawa was constructed from a piece of genuine ray skin, but now is often made from rayon or cotton. The ito should always be kept clean and dry as it wicks away moisture from the hand, keeping it firm and comfortable to hold. Modern ornaments or menuki are added to the tsuka for a more personal touch.
Once the smith is satisfied that the blade has reached the desired specifications, it is polished with a series of progressively finer stones. This polishing brings out the beauty of the hamon, while ensuring that the blade is razor sharp. The keywords I will use are