A little about the katana
The katana evolved as a more sleek and compact alternative to the tachi. Its origins go at least as far back as the Kamakura Period, with several blades dated from that time residing in various national repositories.
Its growth in popularity is believed to have been due to the changing nature of close-combat warfare. The quicker draw of the sword was well suited to combat where victory depended heavily on fast response times. The katana further facilitated this by being worn thrust through a belt-like sash (obi) with the bladed edge facing upwards. Ideally, samurai could draw the sword and strike down the enemy in a single motion. Previously, the curved tachi had been worn with the edge of the blade facing down and suspended from a belt.
The length of the blade varied considerably during the course of its history. In the late 14th and early 15th centuries, katana blades tended to be between 70 to 73 cm (27.6 to 28.7 in) in length. While during the early 16th century, the average length was closer to 60 cm (23.6 in). By the late 16th century, the average length returned to approximately 73 cm (28.7 in).
The katana was often paired with a similar smaller companion sword, such as a wakizashi or it could also be worn with the tantō, an even smaller similarly shaped sword. The pairing of a katana with a smaller sword is called the daishō. The daisho could only be worn by samurai and it represented the social power and personal honor of the samurai
FORGING AND CONSTRUCTION
The authentic Japanese sword is made from a specialized Japanese steel called “Tamahagane” which consist of combinations of hard, high carbon steel and tough, low carbon steel. There are benefits and limitations to each type of steel. High-carbon steel is harder and able to hold a sharper edge than low-carbon steel but it is more brittle and may break in combat. Having a small amount of carbon will allow the steel to be more malleable, making it able to absorb impacts without breaking but becoming blunt in the process. The makers of a katana take advantage of the best attributes of both kinds of steel. This is accomplished through a number of methods, most commonly by making a U-shaped piece of high-carbon steel (the outer edge) and placing a billet of low-carbon steel (the core) inside the U, then heating and hammering them into a single piece. Some sword-makers use four different pieces (a core, an edge, and two side pieces), and some even use as many as five.
The block of combined steel is heated and hammered over a period of several days, and then it is folded and hammered to squeeze the impurities out. Generally a katana is folded no more than sixteen times, then it is hammered into a basic sword shape. At this stage it is only slightly curved or may have no curve at all. The gentle curvature of a katana is attained by a process of quenching; the sword maker coats the blade with several layers of a wet clay slurry which is a special concoction unique to each sword maker, but generally composed of clay, water, and sometimes ash, grinding stone powder and/or rust. The edge of the blade is coated with a thinner layer than the sides and spine of the sword, then it is heated and then quenched in water (some sword makers use oil to quench the blade). The clay slurry provides heat insulation so that only the blade’s edge will be hardened with quenching and it also causes the blade to curve due to reduced lattice strain along the spine. This process also creates the distinct swerving line down the center of the blade called the hamon which can only be seen after it is polished; each hamon is distinct and serves as a katana forger’s signature.
The hardening of steel involves altering the microstructure or crystalline structure of that material through quenching it from a heat above 800 °C (1,472 °F) (bright red glow), ideally no higher than yellow hot. If cooled slowly, the material will break back down into iron and carbon and the molecular structure will return to its previous state. However, if cooled quickly, the steel’s molecular structure is permanently altered. The reason for the formation of the curve in a properly hardened Japanese blade is that iron carbide, formed during heating and retained through quenching, has a lesser density than its root materials have separately.
After the blade is forged it is then sent to be polished. The polishing takes between one and three weeks. The polisher uses finer and finer grains of polishing stones until the blade has a mirror finish in a process called glazing. This makes the blade extremely sharp and reduces drag making it easier to cut with. The blade curvature also adds to the cutting power.
OWNERSHIP AND TRADE RESTRICTIONS
As of April 2008, the British government added swords with a curved blade of 50 cm (20 in) or over in length (“the length of the blade shall be the straight line distance from the top of the handle to the tip of the blade”) to the Offensive Weapons Order. This ban was a response to reports that Samurai swords were used in more than 80 attacks and 4 killings over the 4 preceding years. Those who violate the ban would be jailed up to six months and charged a fine of £5,000. Martial arts practitioners, historical re-enactors and people currently possessing such swords may still own them. The sword can also be legal provided it was made in Japan before 1954, or was made using traditional sword making methods. It is also legal to buy if it can be classed as a ‘martial artist’s weapon’. This ban applies to England, Wales, Scotland and Northern Ireland. This ban was amended in August 2008 to allow sale and ownership without license of ‘traditional’ hand-forged katana.
Cutting can take place any time tomorrow during normal opening hours. However if you want to cut outside of normal class times please call in advance.
“You are the way you are because that’s the way you want to be. If you really wanted to be any
different, you would be in the process of changing right now.”
Sensei Ken Robson Shudokan Black Belt Academy – Aikido Nottingham