The Katana sword, a signature weapon of the Samurai warriors of Japan’s Heian period (794-1185 AD), was designed to be both beautiful and deadly. The blade’s pronounced curve and symmetrical point allowed it to cut more deeply than the straight-edged tachi and also to absorb shock when it struck an enemy. The katana’s elegance was further heightened by its handcrafted hilt, or tsuka, and sheath, or saya. This was an important part of the sword’s aesthetics and served as a symbol of status, adding to the warrior’s mystique.
Swordsmiths begin by obtaining four kinds of metal: Shingane (center metal), Munegane (back metal), Hanokane (blade metal) and Gawagane (side metal). They then heat, soften and fold the steel multiple times in order to remove impurities and even out the carbon content, a process known as “tamahagane.” It is at this point that the sword begins to take shape – although it starts out straight, it eventually curves into its signature form.
After the forming and shaping of the blade, it is reheated in charcoal fire for a process called “Yaki-ire.” This is where the blade’s distinct hamon comes from. The wavy lines of Martensite on the sword’s surface are created through a differential heat treatment: the Shinogichi side is quenched quickly to harden it, while the Mune side is cooled more slowly and not fully – this creates a softer spine that can absorb shock.
The next step is the refining of the katana’s edges, using progressively finer stones. A sword craftsman known as a togishi carefully polishes the blade until it is smooth, shiny and razor sharp. click on this page