Manufacture of the blade

The manufacture of Japanese swords requires great skill and the most successful swordsmiths were well known and respected. This colour woodblock by the artist Ogata Gekko (1859-1920) is of The Swordsmith of Mt Inari, who lived during the Heian period (AD 794-1185).

Japanese sword blades have a hard skin but a relatively soft core. This was achieved by combining steels of different quality and folding the mixture several times while hot. It was then hammered into shape, heated until red hot then quenched in cold water. As well as hardening the blade, this process created natural decorative features. These included a crystalline wave pattern known as the hamon, a cloudy white effect called the nioi (aspect of colour of blossoms on distant trees) and a continuous band of bright crystals called nie (boiling). Polishing was just as important as the initial manufacturing process. It was carried out using as many as twenty different types of stone and made the blade's surface completely even.

By convention, blades are divided into four types according to their length: tachi (great sword) and katana (sword) are more than 60 cm in length. Wakizashi (companion sword) are 30-60 cm and tantō (short sword, or dagger) are about 30 cm. The samurai traditionally wore a pair of swords, one long and one short, known as a daishō.