The Japanese sword is a symbol of unparalleled beauty and quality. Bound closely to the image of the samurai class, the blades are highly prized and honored by collectors all over the world. The history of these incredible weapons and the warriors who wielded them are intimately connected to the development of the Japanese nation and the culture of modern Japan.

The oldest blades, known as Ko-tō (Old Sword) were created by combining tamahagane with steel containing both higher and lower amounts of carbon. Kneading or folding this mixture created a material that could be both strong and flexible, provided the blade survived the creation of the ultra hard edge known as the ha.

To create the ha, the swordsmith would coat the blade with a combination of clay, charcoal, and crushed stone. This mixture was applied in two steps. First a light coat for the entire blade and then a second, thicker coat for the body. Returning to the forge, the blade would be thermal cycled several times. This process of heating and cooling causes the metal to expand and contract, forcing a molecular reorganization which makes the material denser.

The varied application of the clay controls the heat, allowing the edge to become harder while the spine remains flexible. It also results in a beautiful and natural outline of the hardened area, known as the hamon. This way of manufacturing continued for nearly 400 years until the Edo era at the start of the 17th century.

The Edo era represented a major change for Japanese society. The previous century was a time of continuous internal conflict. War, famine, and political intrigue among hundreds of local rulers and warlords kept the entire country on edge. Reunified under the Tokugawa clan in 1603, the new shogunate ruled the country from the city of Edo for 265 years, and "the way of the warrior" was transformed into a far reaching philosophy on how to live a moral life.

The strict set of laws which governed the military rule of the Tokugawa shogunate reached into nearly every aspect of public and private life. The rules even dictated the maximum size for both the Katana and Wakizashi swords and the method of manufacture.

Tamahagane during this era was mass produced using new methods, which resulted in a steel with much higher carbon content. This made the tamahagane stronger but also made it difficult to combine with other grades of steel. As a result, the new swords or Shin-tō were created using a laminating process which wrapped the harder steel around a softer core.

According to polishing experts, older swords were superior in strength and flexibility. This belief led to the cutting down of many longer Ko-tōto fit the blades to the new standard.

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