Katana

Historically, katana (刀) were one of the traditionally made Japanese swords (日本刀) that were worn by the samurai class of feudal Japan, also commonly referred to as a "samurai sword". Modern versions of the katana are sometimes made using non-traditional materials and methods.

The katana is characterized by its distinctive appearance: a curved, slender, single-edged blade with a circular or squared guard and long grip to accommodate two hands. It has historically been associated with the samurai of feudal Japan and has become renowned for its sharpness and strength.

History
The production of swords in Japan is divided into specific time periods: jokoto (Ancient swords, until around 900 A.D.), koto (old swords from around 900–1596), shinto (new swords 1596–1780), shinshinto (new new swords 1781–1876), gendaito (modern swords 1876–1945), and shinsakuto (newly made swords 1953–present).

The first use of "katana" as a word to describe a long sword that was different from a tachi is found in the 12th century. These references to "uchigatana" and "tsubagatana" seem to indicate a different style of sword, possibly a less costly sword for lower ranking warriors. The evolution of the tachi into the katana seems to have started during the early Muromachi period (1337 to 1573). Starting around the year 1400, long swords signed with the "katana" signature were made. This was in response to samurai wearing their tachi in what is now called "katana style" (cutting edge up). Japanese swords are traditionally worn with the signature facing away from the wearer. When a tachi was worn in the style of a katana, with the cutting edge up, the tachi's signature would be facing the wrong way. The fact that swordsmiths started signing swords with a katana signature shows that some samurai of that time period had started wearing their swords in a different manner.

The rise in popularity of katana by samurai 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 sharpened edge facing up. Ideally, samurai could draw the sword and strike 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 katana 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 ($23 5/8$ to $28 3/4$ in) in length. During the early 16th century, the average length was closer to 60 cm ($27 1/2$ in). By the late 16th century, the average length returned to approximately 73 cm ($28 1/2$ 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, a smaller, similarly shaped dagger. 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.

Modern katana (gendaito)
During the Meiji period the samurai class was gradually disbanded and the special privileges granted to them were taken away including the right to carry swords in public. The Haitōrei Edict in 1876 forbade the carrying of swords in public except for certain individuals, such as former samurai lords (daimyo), the military, and police. Skilled swordsmiths had trouble making a living during this period as Japan modernized its military and many swordsmiths started making other items such as farm equipment, tools, and cutlery. Military action by Japan in China and Russia during the meiji period helped revive interest in swords but it was not until the Showa period that swords were produced on a large scale again. Japanese military swords produced between 1875 and 1945 are referred to as guntō (military swords).

During the pre World War II military buildup and throughout the war, all Japanese officers were required to wear a sword. Traditionally made swords were produced during this period, but in order to supply such large amounts of swords blacksmiths with little or no knowledge of traditional Japanese sword manufacture were recruited. In addition, supplies of the Japanese steel (tamahagane) used for sword making were limited, so several other types of steel were used, as well. Short-cuts in forging were also taken, such as the use of power-hammers, and tempering the blade in oil, rather than hand forging and water tempering. These techniques generated swords without the various characteristics associated with "true" Japanese swords. The non-traditionally made swords from this period are called "showato" after the regnal name of the Emperor Hirohito, and in 1937, the Japanese government started requiring the use of special stamps on the tang (nakago) to distinguish these swords from traditionally made swords. During this period of war, older antique swords were remounted for use in military mounts. Presently, in Japan, showato are not considered to be "true" Japanese swords and they can be confiscated. Outside of Japan, however, they are collected as historical artifacts.

Post World War II
In Japan from 1945 to 1953 sword manufacture and sword related martial arts were banned. Many swords were confiscated and destroyed, and sword-smiths were not able to make a living. Since 1953 Japanese sword-smiths have been allowed to work, but with severe restrictions: swordsmiths must be licensed and serve a five-year apprenticeship and only licensed swordsmiths are allowed to produce Japanese swords (nihonto), only two long swords per month are allowed to be produced by each swordsmith, and all swords must be registered by the Japanese Government.

Outside Japan, some of the modern katanas being produced by western sword-smiths, use modern steel alloys, such as L6 and A2. These modern swords replicate the size and shape of the Japanese katana, and are used by martial artists for Iaido and even for cutting practice, called (tameshigiri). The use of modern steel and technology can create strong blades without the risk of damaging or destroying the artisan's hard work.

Mass-produced swords including iaitō and shinken in the shape of katana are available from many countries, though China dominates the market. These types of swords are sometimes called "replica." They are mass-produced and made with a wide variety of steels and methods.

Description
The katana is generally defined as the standard sized, moderately curved (as opposed to the older "tachi" style featuring more curvature) Japanese sword with a blade length greater than 60 cm ($23 1/2$ inches).

With a few exceptions, katana and tachi can be distinguished from each other, if signed, by the location of the signature (mei) on the tang (nakago). In general, the mei should be carved into the side of the nakago which would face outward when the sword was worn. Since a tachi was worn with the cutting edge down, and the katana was worn with the cutting edge up, the mei would be in opposite locations on the nakago.

The katana is characterized by its distinctive appearance: a curved, slender, single-edged blade with a circular or squared guard and long grip to accommodate two hands. It has historically been associated with the samurai of feudal Japan, and has become renowned for its sharpness and strength.

Etymology and loanwords
"Katana" is the term now used to describe nihontō that are 2 shaku (606 mm / 23.9 in) and longer, also known as "dai" or "daito" among Western sword enthusiasts although daito is a generic name for any long sword.

Pronounced, the kun'yomi (Japanese reading) of the kanji 刀, originally meaning dao (sword) or knife/saber in Chinese, the word has been adopted as a loanword by the Portuguese language. In Portuguese the designation (spelled catana) means "large knife" or machete. As Japanese does not have separate plural and singular forms, both "katanas" and "katana" are considered acceptable forms in English.

Forging and construction
Katanas are traditionally made from a specialized Japanese steel called "Tamahagane", which is created from a traditional smelting process that results in several, layered steels with different carbon concentrations. This process helps remove impurities and even out the carbon content of the steel. The smith begins by folding and welding pieces of high and low carbon steel several times to work out most of the impurities. The resulting block of steel is then drawn out to form a billet.

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 differential hardening or differential quenching: the smith 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 any or none of ash, grinding stone powder, or rust. The edge of the blade is coated with a thinner layer than the sides and spine of the sword, heated, and then quenched in water (some sword makers use oil to quench the blade). The slurry causes only the blade's edge to be hardened and also causes the blade to curve due to the difference in densities of the micro-structures in the steel. When steel with a carbon content of 0.7 percent is heated beyond 750 °C it enters the austenite phase. When austenite is cooled very suddenly by quenching in water the structure changes into martensite, which is a very hard form of steel. When austenite is allowed to cool slowly its structure changes into a mixture of ferrite and pearlite which is softer than martensite. This process also creates the distinct line down the sides of the blade called the hamon, which is made distinct by polishing. Each hamon and each smith's style of hamon is distinct.

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. However, the blunt edge of the katana is often given a matte finish to emphasize the hamon.

Usage in martial arts
Katana were used by samurai in practising several martial arts and modern martial artists still use a variety of katana. Martial arts in which training with katana is used include Iaijutsu, battōjutsu, iaidō, kenjutsu, Shinkendo, kendo, Aikido, Ninjutsu.

Storage and maintenance
If mishandled in its storage or maintenance, the katana may become irreparably damaged. The blade should be stored horizontally in its sheath, curve down and edge facing upward to maintain the edge. It is extremely important that the blade remain well-oiled, powdered and polished, as the natural moisture residue from the hands of the user will rapidly cause the blade to rust if not cleaned off. The traditional oil used is choji oil (99% mineral oil and 1% clove oil for fragrance). Similarly, when stored for longer periods, it is important that the katana be inspected frequently and aired out if necessary in order to prevent rust or mould from forming (mould may feed off the salts in the oil used to polish the katana).

United Kingdom
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 licence of 'traditional' hand-forged katana.

Ireland
Under the Firearms and Offensive Weapons Act 1990 (Offensive Weapons) (Amendment) Order 2009, katanas made post-1953 are illegal unless made by hand according to traditional methods.