Worth knowing

The history of Japanese swords

An overview of the katana (Japanese sword).  Then you will also know why it has a certain price.

Swords forged with the spirit of Japan
Katana (samurai sword) is a generic term for swords forged in the manner originally developed in Japan. They are categorised according to size into katana (tachi, uchigatana), wakizashi and tanto. Craftsmen who make katana are known as "toko (sword master)", "tosho (sword master)" or "katana kaji (swordsmith)".

The soul of the samurai
In addition to its use as a weapon, its beautiful form has also had a symbolic meaning since ancient times, and many are collected and highly prized as objects of art. Ancient and unbroken lineages, including the imperial family and shrines, value treasure swords (such as the Amenomurakumono tsurugi) as a show of power. They also functioned as pillars of spiritual culture, "the soul of the samurai against the backdrop of military rule". They are characterised by a process of "folding and forging" two types of metal, hard, brittle steel and soft iron, so that toshin (blade body) and nakago (core) are combined. The nakago has holes (mekugi holes) to attach the blade body to the tsuka (handle) with pin fasteners.

The katana is not only a weapon, but also a craft
In contrast to the swords of other countries, the greatest speciality of the katana is that, in addition to the fittings (koshirae), the body of the blade itself also has artistic value. The katana is mentioned in a poem entitled "A Poem about the Katana" by Ou-yang Hsui in Baisong. This poem describes a merchant from Yueh (southern China) travelling to Japan to buy katana, which are already referred to as treasure swords due to their artistic qualities evident in the fittings and appearance. Although the poem "A Poem about the Katana" is primarily about lamenting the fact that books lost in China still exist in Japan, and not about the katana, it shows that the beauty of the katana was already recognised as one of Japan's export goods by overseas merchants from the late Heian period to the early Kamakura period.

Do not break and do not bend
It is believed that the manufacturing process of the katana was essentially developed with the aim of achieving three contradictory properties simultaneously: "non-breaking, non-bending and sharp cutting". In modern metallurgy, "not breaking and not bending" is referred to as "compatibility of strength and toughness".

Do not break and cut sharply
"Cutting sharp" and "not breaking" are also difficult to reconcile. This was achieved by the so-called functionally graded structure, in which the cutting edge is hard and the hardness gradually decreases towards the core, creating residual compressive stresses at the cutting edge. The above explanation shows that the ideal state is realised in the entire blade, so that invisible defects can cause a sword to break easily. However, a katana in its ideal state is rightly described as "the strongest cutting tool in the world". The sharpness of katana is reported everywhere. A notable example is the 'Kabuto-wari (helmet splitting)' with katana of the Dotanuki group led by Kenkichi SAKAKIBARA.

Katana specialises in 'cutting, separating'
A katana is not really light if you compare the blade length, because its handle is longer than that of other swords. However, it is one of the lightest swords for two-handed use. A katana is originally suitable for "slashing". However, when cutting, one must slide and pull so that the force is directed at a right angle against the object to be cut, as the sword itself is light. For the same reason, a sword that is to be sharpened for "cutting and killing" is sharpened so that it glides like a kitchen knife. If you trace the history from the Kofun period back to the Nara period, when swords were separated between ceremonial use and actual use, "Keito Tachi" and "Kurozukuri-no Tachi" were only meant for "cutting". In the Heian period, the "Kogarasu" adopted the "Kissaki moroha-zukuri" (style with a double-edged point) to be suitable for "stabbing" as well, but later the swords had a curve to be suitable for "cutting" from the wrist.

Forging technique of the katana
The forging technique of the katana, which was very advanced at the time, aimed to achieve three highly sought-after characteristics: "not to break, not to bend and a razor-sharp edge.
Tatara-buki method; the type of steel used to make a katana is called Japanese steel or tamahagane. Tamahagane is produced using the "Tatara-buki method", an originally Japanese method of steel production. By using black iron sand found on the beaches of Japan, rapid reduction at low temperatures is achieved and, compared to modern steelmaking processes, high quality steel with few impurities is produced that is not dependent on imported iron ore.
Heated tamahagane is hammered into a thin flat plate using a tsuchi (hammer). When it is quenched in water and quickly cooled, the excess carbon flakes off. This process is called "Mizuheshi" (removal of carbon with water). These are processes for producing raw metal called heshi (removal process).

Tsumi wakashi (stacked and heated)
This case-hardened piece is called heshi gane (abraded metal), which is smashed into small pieces of metal with a tsuchi (hammer). These pieces of metal are stacked on the tip of a forging tool called a "teko" and wrapped in traditional Japanese paper. Straw ash is then applied and coated with clay slurry. The whole thing is then heated in a kiln (hodo) until the clay surface melts. The straw ash and clay prevent the steel from scaling during heating and oxidisation. It is then hammered into a 6x9 cm block with a kozuchi (light hammer). If there are not enough pieces of iron, more are stacked, heated, hammered with a kozuchi and moulded into an ingot weighing 1.8 to 2.0 kg. This process is known as "tsumi wakashi" (stacked and heated). In addition to tamahagane, pig iron (sentetsu), which contains a lot of carbon, and pure iron, called Hocho tetsu, are also processed using tsumi wakashi and shita-gitae.

Shita-gitae (foundation forging)
The red-hot block is struck and stretched with a tsuchi (hammer) and then folded back to the centre of its length, which is called the "folding method of forging" and is performed repeatedly. The word "muko-zuchi" describes the method in which the tosho (yokoza, master) and his disciple (sente, helper) take turns striking the blade body with the tsuchi, and this is the root of the word "aizuchi wo utsu" (striking). In this step, the blade is folded about five or six times.

Tsumi wakashi (stacked and heated) again
After completing shita-gitae with three types of steel, tamahagane (literally "jewelled steel"), sentetsu (pig iron) and hocho tetsu (literally "kitchen knife steel", pure iron), they are hammered again with a kozuchi (light hammer) to produce pieces of metal that are selected according to the correct steel composition and stacked and shaped like the first tsumi wakashi. In this step, four types of steel with different carbon content, shingane (centre metal), munegane (back metal), hanokane (blade metal) and gawagane (side metal), are produced.

Forging (Age-gitae, final forging)
Shingane is forged 7 times, munegane 9 times, hanokane 15 times and gawagane 12 times. Repeated forging after folding back the forged and stretched steel removes impurities such as sulphur, excess carbon and non-metallic impurities, resulting in a strong and homogeneous steel.

Tansetsu (forge welding) and wakashi-nobe (heating and lengthening)
After the four types of steel - shingane (centre metal), munegane (back metal), hanokane (blade metal) and gawagane (side metal) - have been produced by shita-gitae (forging), the second tsumi wakashi (stacked and heated metal) and age-gitae (finish forging), three layers of munegane, shingane and hanokane are forged, beaten and stretched to obtain four times the thickness of the material, 20 mm thick, 40 mm wide and 90 mm long, and then cut into four pieces. This is called "core metal (芯金)". The gawagane is also heated, beaten and stretched so that it is twice as long as the core metal, and then cut in the middle to create two gawagane of the same length as the core metal. Gawagane, core metal and the other gawagane are stacked in this order, heated, forged and welded, then upset and stretched into a plate 15 mm thick, 30 mm wide and 500 to 600 mm long. Teko" is cut off, then "Nakago", the handle of the sword, is heated, forged and welded.

By now at the latest, it should be clear to anyone that such a sword has its justifiable price. But let's go on.

Sunobe (moulding of the blank)
Sunobe" is made by beating and lengthening to form the shape of the katana, and kissaki (piercing point) is made by cutting off the end. Since this rough shape determines the final shape of the katana, it is carefully moulded by beating with a kozuchi.

Hizukuri (shaping with heat)
The mune (back) of the blade is struck to form the base of a triangular shape, and the blade side (hirachi) is struck and extended to reduce the thickness. Then the mune of the nakago is struck to round the trailing edge, and finally the "shinogichi" (ridge line) is struck and shaped. The entire blade body is heated at a lower temperature until it turns a reddish-brown colour.

Karajime (cold forging)
After cooling, the black stain is removed by grinding with a coarse polishing stone, and the hirachi (blade) and shinogichi (ridge line) are hammered with a kozuchi (light hammer) and cold forged. The straight lines of the mune and blade are adjusted, and unevenness is scraped off with a special metal plane called sen (銑, with the radical of 金 and 舌, from the right). In this step, the "hawatari (length of the blade) and the "machi (notch)" are determined.

Namatogi (rough grinding)
Namatogi" is performed to grind out the marks left by the plane with a polishing stone. After oil and grease have been removed with straw ash and water, the sword is dried.

Tsuchioki (bottom coating)
In preparation for "yaki-ire (quenching)", in which the heated blade is quickly cooled with water or other liquid, "tsuchioki (ground coating)" is performed, in which three types of yakiba-tsuchi soil (soil used for quenching) are applied to hirachi (blade), hamon (blade pattern) and shinogichi (burr line). Yakiba-tsuchi soil (soil for quenching) is applied thinly and evenly on the hirachi (blade side), then hamon (blade pattern) is designed with a writing brush using yakiba-tsuchi soil for quenching for hamon. Finally, a thicker layer of Yakiba-tsuchi earth (for quenching) is applied for the shinogichi (ridge line) from the hamon (blade pattern) to the mune (back). By using a stronger concentration of yakiba-tsuchi earth for quenching on the shinogichi (ridge line), the blade side is cooled quickly and completely quenched by yaki-ire during rapid cooling, while the mune side is cooled relatively slowly and is not completely quenched. Quenching makes the sword harder, the metal expands and creates the pronounced curve of a katana. The mune expands less and takes on the characteristic of toughness rather than hardness, which supports the steel of the blade side, which is hard but otherwise breaks easily.

Yaki-ire (quenching)
In yaki-ire, the tosho generally dims the light in the workshop and judges the temperature of the steel by its glow. The tsuchioki-coated blade is inserted deep into the hodo, and the entire blade is heated evenly from end to end to about 800 degrees. The temperature is the most important thing, and the optimum heat condition is checked with the utmost care. The body of the blade is then quickly immersed in a tank of water and rapidly cooled. As mentioned earlier, the blade warps in the water, and after it has cooled completely, it is pulled out and sharpened with a coarse polishing stone, and the yakiba (焼刃, cutting edge) is checked. The blade is then reheated in a charcoal fire for "yaki-modoshi (hardening)". This work is called "Aitori (neutralising)". As the blade also warps a little to one side, it is struck with a kozuchi (light hammer) on a wooden base to straighten the blade. The nakago (core) is also hardened and moulded. After yaki-ire (quenching), the surface of the blade is very hard and is called martensite. Depending on how the martensite looks, the hamon (blade pattern), which looks like round particles on the surface of the metal to the naked eye, is called nie (literally "boiling") and is distinguished from the nioi (literally "fragrance"), which looks like fine lines because the individual particles cannot be distinguished. In addition to water, other cutting tools are also quenched in oil, as are Japanese military swords during the war.

Kajioshi (final sharpening)
The swordsmith changes the curvature of the katana after the yaki-ire (quenching) is completed and performs a rough grind. In this step, small scratches, the thickness of the blade and the jiba (blade surface) are checked and the final adjustment is made.

Nakago jitate (core shaping)
Nakago (core) is shaped with a sen (sharpening tool) or file, and a hole is usually drilled for a mekugi (fixing pin) used to secure the tsuka (handle), two in the case of a sword for iaido (Japanese martial arts). Then yasurime (to prevent the hands from slipping on the hilt) is added, which is unique in swordsmanship.

Meikiri (carving inscription)
Finally, the craftsman uses a tagane (drill) to carve his own name, address or the year in which the sword was made into the nakago (core) as a mei (inscription). This completes the work of the swordsmith, then a togi-shi (polisher) gives the sword its final polish. When polishing katana, there are major differences to other cutting tools; in addition to the sharpness as a cutting tool, attention is also paid to the decorative elements of a katana, and the entire body, not just the blade part, is polished.
After the forging process, the saya-shi (scabbard craftsman) makes the matching saya (scabbard) for the katana. Katana are not only finished by a swordsmith. Other craftsmen, including a togi-shi (polisher) and a saya-shi (scabbard maker), put the finishing touches to the sword.

If you have managed to read all this information, then you now know that katanas costing, for example, $200.00, $400.00 or even $500.00 were never made as described here. These cheap swords are replicas made of simple stainless steel, they are not hand-forged swords. This should be understandable. These replicas can never match the hardness and sharpness of a real katana.