The katana [ka.ta.na] ( Japanese 刀) is the Japanese long sword (Daitō 大刀). In Japanese common today, the term is also used as a general term for sword. Weapons made today are also called shinken (真剣) , "real sword".
The word katana is the kun reading of the kanji 刀, the on reading is tō, from Chinese dao. It denotes a particular curved sword shape with a single edge. The counterpart is the double-edged tsurugi (also called ken 剣).
The blade shape is similar to that of a saber, but the hilt (tang) - called a nakago in Japanese - is not curved against the cutting side as is often the case with the classic saber.
The biggest difference, however, is in the handling. While the katana is usually wielded two-handed, the average saber is designed as a one-handed weapon. This difference leads to a different fencing style.
The katana evolved from the tachi 太刀 (long sword) in the 14th century and was traditionally used by Japanese samurai from the late 15th century (early Muromachi period), especially in combination (Daishō 大小, large-small) with the short wakizashi 脇指 (shōtō 小刀, short sword).
It bears great resemblance to the earlier Chinese Miao Dao and the swords of the northern Japanese Ainu. What makes a genuine Japanese blade unmistakable is the hardening zone (hamon 刃文) created by special forging or hardening techniques,
as well as (in koshirae 拵え) the handle (tsuka 柄) usually covered with ray skin or also shark skin (false ray leather) (samegawa 鮫皮) and usually artistically wrapped with silk ribbon. However, leather handle wraps were also used in some cases. Carved hardwood or ivory handles existed only for decorative or presentation swords.
A katana blade usually consisted of at least two different types of steel, a ductile one for the core and a hard one for the cutting edge. Both components were first "refined" individually by multiple folding and welding before being forged together to form a blade.
The katana in the narrower sense is a one-and-a-half-handed sword curved toward the back, with a blade over two shaku 尺 long (that is, about 60.6 cm) and a handle of varying length.
It weighs approximately 900 to 1400 grams. A blade with less than two shaku is a one-handed wakizashi (or Shōtō = short sword) and one with less than one shaku is a fighting knife (Tantō, Aikuchi, Hamidashi).
The scabbards of all three types of swords are called saya 鞘 and are made of lacquered wood. Only the mass-produced military swords of the 20th century came with tin scabbards, but they had a wooden lining.
However, other swords were used in Japan, such as a longer and heavier version of the katana, the Dōtanuki.
This is known from the television series Lone Wolf & Cub, as well as the movie Okami - The Sword of Vengeance. It was also favored by Katō Kiyomasa, a general of Toyotomi Hideyoshi.
The swords or the blades are assigned to different periods→ Nihontō. Also, katanas are distinguished according to the five classical swordsmithing traditions Gokaden.
Katana and wakizashi were always worn together with the edge up through the obi (belt). This is a "civilian" way of carrying, which prevailed when, after the end of the intra-Japanese wars in the early 17th century, wearing armor was no longer part of the samurai's daily routine.
When entering a house, the katana was detached from the obi and, if hostilities were to be feared, carried ready for use in the left hand or, as a sign of confidence, in the right hand with the hilt to the rear.
When sitting, the katana lay within reach on the floor, while the wakizashi often lingered at the hip. On the street, the swords were carried in a suitable outfit (koshirae), which included a lacquered sword scabbard (saya).
In one's own home, when not in immediate use, the blade was kept in the shirasaya, which protected the steel from corrosion by a particularly tight fit and the untreated magnolia wood. Nowadays, so-called Shirasaya katanas are often offered, whose complete mount consists of untreated wood.
This inconspicuous mount without tsuba or other decoration was often used towards the end of the 19th century after the imperial ban on sword weapons, because the shirasaya mount resembled a Bokutō, or wooden sword.
In later times (until the 20th century), there were concealed blades similar to the stick swords of the West; this often involved concealing a (short) sword blade in a mount that looked like a walking stick made of bamboo or a stick cut from a branch.
Armor included the tachi until the early Muromachi period (i.e., the late 14th century). From this time on, the tachi, which were worn with the edge downwards on a hanger, were increasingly replaced by katanas.
These had a textile (silk) band (sageo) to secure the saya to the obi. The tachi was usually accompanied by a typical fighting knife (Tantō), the katana was supplemented by the wakizashi.
Many steps are necessary to make a katana. The production of such a sword takes several days to weeks. First, broken pieces of the tamahagane steel obtained in a kind of racing furnace (tatara) are laid together to form a block and doused with mud and ash.
This ensures that impurities combine with it and are thus released from the steel. The whole is then heated to welding temperature (white hot) to join the fragments of tamahagane by fire welding.
After this process, the block of tamahagane is folded up to 15 times so that the carbon is evenly distributed. This homogenization later provides uniform hardness and toughness of the blade if the heat treatment succeeded. After this process, up to 32,768 layers of steel lie on top of each other.
A tougher steel core is now forged into the Tamahagane block, which is to form the outer layer of the blade construction, because otherwise the blade could break under load (there are also other techniques).
Now the block is forged into length and shaped into the blade in days of manual work. A special scraper (SEN) is used to refine the shape of the blade.
In the next step, hardening, the sword is first coated with a layer of clay using a fine bamboo or metal spatula. This is applied to the cutting edge thinner than the rest of the blade and this is done in a pattern typical of the particular blacksmith.
After drying, the blade is brought to hardening temperature (about 800 °C) in a charcoal fire and quickly cooled in warm water. This solidifies the structure of the steel, and martensite, a particularly hard steel modification, is formed.
The cutting edge is cooled more quickly by the hardening process and therefore becomes harder, while the blade body remains softer and tougher. This differential hardening shows up in the cutting edge as a hamon, a structure with various fine expressions of martensite (NIOI and NIE).
This is a more or less clearly defined area of the cutting edge (but only evident as a result of the final traditional Japanese polishing of the blade)....
The blade is then filed over again and, if necessary, a signature (mei) is added, which is hammered into the tang (nakago) with a small chisel.
After this treatment the grinder (togishi) gets the sword. In about 120 hours, he gives the surface of a katana the incomparable appearance, but also the necessary sharpness.
Some blades are then given a decoration (horimono) by the engraver, which is worked in with small chisels. Other specialized craftsmen make the handle (tsuka), the scabbard (saya) and the metal fittings (kodogu) in custom work.
Traditionally, Japanese sword blades are made of tamahagane. They are made in an almost unique way in a sophisticated process. The reason for this manufacturing method lies in the iron sand used, which was cleaned of impurities under high temperatures to produce purer iron.
The steel was extracted from local iron sand in a tatara (a rectangular racing furnace). It was initially inhomogeneous and had an uneven carbon content of about 0.6-1.5% (tamahagane).
However, steel with uniform carbon content of about 0.6-0.7% is needed for the blade. In order to eliminate all impurities and to control and evenly distribute the carbon content of the blade, a special folding technique was developed, which was very effective but also labor intensive.
A distinctive feature of iron sands is their low sulfur and phosphorus content. These elements are undesirable in steel because they cause segregation (significant disturbances in the steel structure). Therefore, a low-sulfur charcoal is also used in forging.
First, the steel is forged from smaller fragments into an ingot, which is then repeatedly heated, folded alternately transversely and longitudinally, and forged out again.
During forging, a significant loss of material occurs due to scaling of the steel, and at the same time the carbon content is also reduced by oxidation.
To compensate for the loss and control the carbon content, steel ingots with different carbon contents are bonded together during the forging process.
Further folding and forging thus results in the numerous wafer-thin "layers" of steel that can be made visible on the blade surface by special grinding and polishing techniques (Hada).
This forging process is used exclusively to clean and homogenize the steel and to control the carbon content (refining steel).
The view that a good katana must be forged from as many layers as possible is based on a misunderstanding. Depending on the quality of the tamahagane and the desired carbon content, the ingot is reforged a total of about 10 to 20 times.
If the steel is simply folded ten times, the result is already 1024 layers; if the steel is reforged 20 times, the result is more than a million layers. The forger continued this process only until he obtained a completely uniform ingot with the desired properties.
Unnecessary further forging only made the steel softer and would have led to further loss of material through burn-off.
In World War II Guntō machine-made katanas, the steel was typically 95.22% to 98.12% iron and had a carbon content of over 1.0%. As a result, the steel was very hard. In addition, it contained a variable amount of silicon, which gave the blade greater flexibility and resistance.
Small amounts of copper, manganese, tungsten, molybdenum and (unintentional) traces of titanium were also present in the blade material, depending on the origin of the raw material.
Not every steel is suitable for swords. Unlike cheap copies, a forged original is not made of 440 A stainless steel (1.4110)→knife steel. This is a specially developed knife steel which, as a rolled steel with a Rockwell hardness of up to 56 HRC, is not suitable for the manufacture of sword blades.
In addition, an original does not have a serrated edge, engraving or etching to mimic a hamon. A true hardening zone can only be achieved by a special treatment of the steel (see: martensite).
The hardening of the cutting edge area up to 62 HRC, with the elasticity given at the same time, makes the special quality of Japanese blades. The high hardness of 60-62 HRC also ensures that the sharpness is retained for a long time (edge retention).
However, the reason for the superior cutting performance in the pressure cut (the opposite is the pull cut with back and forth movement of the blade as in saws), which is also important in shaving and is strictly linear at right angles to the cutting edge, is the fine iron carbide, which produces a very thin cutting edge without chipping due to sharpening grinding.
This fine iron carbide is mainly found in rusting steels, high-tech stainless steels cannot achieve the fine cutting edge without microscopic nicks, but they are excellent in traction cutting due to the microscopic nicks and breakouts, which work like a micro saw.
In the early Middle Ages, the Vikings were already folding blade steels in an artistic way; there were very attractive damascened blades that never existed in this form in Japan.
The Franks also produced good steel, and the blades made from it could do without the folding of the steel and the homogenization it achieved.
The Japanese steel products were not comparable to European blades in terms of the manufacturing process and the properties obtained, as well as in terms of surface finish, because they served a completely different war technology and because armor in Japan developed completely differently from European ones.
The swordsmith has always been faced with the task of creating a weapon that is both sharp and durable - the sword must not quickly dull, rust or break.
Depending on the carbon content of the steel and the hardening process, it can produce a blade that is rich in martensite and thus very hard and capable of cutting, but also brittle and fragile.
In contrast, using a more ductile steel will dull the blade more quickly.
This conflict of goals is solved in the katana by a sandwich construction. The predominant technique embeds a core of ductile, slightly softer, lower-carbon steel in a sheath of harder, higher-carbon steel:
The smith folds a long, narrow ingot of "hard steel" lengthwise in a U-shape and welds in a matching ingot of "soft steel" in the fire.
This combined ingot is forged into the raw blade so that the closed side of the "U" becomes the cutting edge of the blade. The combined ingot is no longer folded in the process.
Other designs may, for example, inversely embed the hard blade steel in a "U" of mild steel, or the smith may combine hard blade steel and soft back steel with two side layers of medium hard steel.
There are a variety of more elaborate techniques, but these do not necessarily result in better blades; rather, they were often introduced by weaker forges to circumvent the difficulties of the difficult hardening process.
Very short blades were also sometimes made from a single steel (mono-material).
Similar to Western swordsmiths of the Middle Ages who used differential hardening, Japanese smiths harden the blade in a differentiated manner rather than uniformly.
The blade is often forged almost straight and receives the typical curvature through hardening, whereby the blade edge has a hardness of about 60 Rockwell, but the back of the blade only a hardness of about 40 Rockwell.
The hardening process is based on the change in the lattice structure of the steel, austenite is transformed into martensite, which has a higher volume, due to the quenching caused by the temperature gradient of the hardening bath (traditionally in a water bath).
Thus, the blade expands and curves at the cutting edge. The curved blade has the advantage of cutting better and making the blow more effective, which is why it has become popular over time.
Before hardening, the blade is coated with a mixture of clay mud, charcoal powder and other ingredients. This coating is much thinner on the cutting edge than on the rest of the blade.
For hardening, the blacksmith also heats the cutting edge more than the back of the sword, and it is essential that despite this heat gradient (for example, 750-850 °C) in cross-section, the cutting edge and the back of the blade are heated evenly along their length.
When quenched in hot water, the hotter cutting edge (Ha) cools faster and forms a higher proportion of hard martensite than the rest of the blade.
The demarcation of this narrow zone is clearly visible after the blade has been hardened and polished (hamon). It is not a defined line, but a more or less wide zone.
Some smiths make the hardening zone of the blade more vivid by making the clay coating wavy, irregular or with narrow transverse lines before drying. The resulting shapes of the hamon can be an indication of the school of smithing, but are not usually a mark of a particular quality.
There are very high quality blades with millimeter narrow, straight hamon, and there are shapes with very large waves that are considered less than subtle (and vice versa).
A hamon with many very narrow "waves" can produce narrow more elastic zones (ashi, "feet") in the cutting edge that can prevent a crack from continuing in the cutting edge. However, a blade with a transverse crack is generally unusable for use.
By varying the duration and temperature of heating before quenching, the smith can produce other effects on the surface of the blade (for example, nie and nioi - mist cloud-like martensite formations with varying particle sizes that can also agglomerate to show different structures).
The hardening process (austenitizing and quenching) can be followed by tempering, in which the hardened blade is heated in embers or on a copper block previously heated to red heat up to about 200 °C, which relaxes the hardening structure (the martensite). This gives the blade a unique combination of hardness and toughness.
Tempering (hardening and tempering) is a delicate step in the making of the katana that even an experienced smith can fail. In this case, the blade can be rehardened and tempered.
This can be repeated only a few times, and if these rescue attempts are also unsuccessful, the blade is discarded.
The combination of a hard cutting edge with an elastic blade core gives the katana blade enormous toughness with sustained sharpness.
After the blacksmith has finished his work, which includes a first surface treatment with the sen, a kind of metal scraper, he hands the sword over to a polisher, called togishi.
His job is to grind and polish the blade, first with coarse stones and later with progressively finer stones, in a process that takes about 120 hours.
The togishi not only sharpens the blade, but also uses different techniques to bring out the surface steel structures, i.e. the hamon and the hada, the "skin", which gives an insight into the forging technique. Even minor flaws can sometimes be concealed in the process.
Today, more than the weaponry aspect of Japanese blades, it is the high quality of the steel and the aesthetic qualities that are appreciated and admired, although these can only be revealed through good craftsmanship in polishing.
This includes accurately preserving the shape and geometry of the blade as it was laid out by the blacksmith. Therefore, the polisher's craft involves a very precise knowledge of the forging styles of individual blacksmiths and blacksmithing schools of past centuries.
Unknowledgeable hands can ruin a blade beyond repair by improper sharpening/polishing.
The different curvature (sori) of the katana is intentional; it originated in a development process over a thousand years long (of course also parallel to the armor of the samurai) and varied constantly until it finally represented a perfect extension of the slightly bent arm.
It also partly results from the applied heat treatment: during differential hardening, the cutting part of the sword expands more than the back.
Within the basic pattern of the katana, many variations are possible, depending partly on the preferences of the smith and his customers, and partly on the tradition of the particular sword school.
The geometry of the blade (Tsukurikomi) was also determined by the intended use: For use against armored opponents, it was more wedge-shaped in cross-section and thus less sensitive;
for use against unarmored opponents, it was thinner and thus more suitable for a cutting blow.
The smith can specify the extent and center of curvature when forging the raw blade and can also rework it after hardening. Likewise, the blade can be given a uniform or tapering width, a long or short point (kissaki).
The smith can give the blade hilt (nakago) a specific shape, make the back of the blade round or square, determine the shape of the hardening line (hamon), and influence the structure and appearance of the steel.
Grooves and engravings can also be cut into the unhardened areas of the blade.
All these factors are also evaluated by connoisseurs and collectors according to aesthetic criteria.
There are many defects that can occur during forging or due to incorrect handling.
A distinction is made between fatal flaws, which render the blade unusable, and non-fatal flaws, which are correctable or only disturb the appearance of the sword.
The flaws in detail are:
After sharpening, a scabbard (saya) and a handle (tsuka) are made for the finished blade from magnolia wood boards. The scabbard can have an octagonal (with angular or rounded edges), oval or elliptical cross-section.
The handle is attached to the sword tang (nakago) (tang provided with a mekugi-ana) with a pierced conical pin made of bamboo (mekugi).
The opening of the scabbard (koiguchi, "carp mouth") is covered with a finial of horn or bone. However, the scabbard and sword hilt can be left in their raw state (shirasaya, "white scabbard") if they are used only to store the blade.
For a full assembly (koshirae), the scabbard is painted dust-free; it may be previously covered with ray skin (seed) or decorated with inlay work. Its exterior is fitted with a perforated round button (kurigata, "chestnut shape") to which the sword strap (sageo) of silk, cotton, or leather is attached. Military weapons may also have a special lock to prevent the sword from accidentally sliding out of the scabbard.
The complete assembly of a katana also includes the following metal parts:
the habaki, a ferrule at the base of the blade in front of the thrusting blade, used to secure the tight fit of the katana in the scabbard and to hold the tsuba in place
For a daisho combination, the decorations of the wakizashi (short sword) are matched to those of the katana.
The classic wakizashi also included the by-knife (kogatana or kozuka (the handle of the kogatana)) and the sword needle (kōgai) - alternatively a pair of metal chopsticks - which were carried on both sides next to the blade in the saya and inserted through matching openings in the tsuba.
The sword needle, like an awl used in our country, was used to repair the movable armor parts connected with silk ribbon or to straighten the winding of the sword hilt.
A katana was mainly used as a cutting weapon, but also as a thrusting weapon, which can be used both two-handed and one-handed. The oldest Japanese sword fighting systems trace their origins back to the 12th-13th centuries.
The central element of Japanese swordsmanship (kenjutsu) and the arts based on it (such as Iaidō) is that the blade axis is never struck perpendicularly against the target, but is always wielded in a drawing-cutting motion.
Thus, the blows are more like cuts. The curved shape of the blade also takes this into account.
The Japanese sword master Miyamoto Musashi wrote the book Gorin no Sho (The Book of Five Rings), in which he explains and esoterically justifies his two-sword form (Niten-Ryu).
Kenjutsu, the art of sword fighting in practice, has evolved into today's gendai budo. The art of sword drawing is called Iaidō and is a more meditative form of combat, fighting an imaginary enemy.
Kendō is the art of fencing with a bamboo sword (shinai), wearing - similar to European fencing - a head guard with a protective grill for the face and armor. This type of sword fighting, depending on the respective style (Ryu), sometimes takes a competition-oriented direction.
Today, numerous traditional (Koryū) sword schools still exist in Japan, having survived Emperor Meiji's general ban on swords. Among the best known are Kashima Shinto Ryu, Kashima Shin Ryu, Hokushin Ittō-ryū, and Katori Shinto Ryu.
Japanese blacksmiths have always been held in high esteem, and the Japanese Emperor Go-Toba (1180-1239) had even learned the art of swordsmithing himself and divided the empire's blacksmiths into classes of rank, the first of which had special privileges.
Likewise, there are reports of famous swordsmiths such as Masamune, Muramasa, and others whose swords possessed a spiritual power that made them superior to other swords.
In later times - especially in the Tokugawa shogunate of the Edo period - the katana was transfigured into the "soul of the samurai".
However, by this time the great warring conflicts in Japan had ended and the samurai had to justify their special position in the newly established rigid estate state by distinguishing themselves from the lower estates.
One of the most common misconceptions is that the steel of a blade is folded an incredible number of times, supposedly giving it superior strength and quality. However, the number of folds is often confused with the number of plies.
The number of layers is two to the power of the number of folds, so a bar folded six times already has 26 = 64 layers, and thus a bar folded 20 times already consists of more than 1 million layers.
Likewise, in the West, the misconception is widespread that for the Japanese sword, the combination of steel and iron is folded together and forged into the blade.
This folding process (tempering), however, concerns the preliminary stage, namely the production of the ingots of cutting steel and core steel, which are then welded together to form the raw blade.
This misunderstanding is possibly based on a false analogy with Damascus steel, which, however, is produced using a completely different forging technique.
The main purpose of multiple folding and machining is to evenly distribute the varying carbon content caused by the steel's manufacturing process along the entire length of the blade.
This is the only way to ensure that the finished forged blade will not crack and break during the hardening process and, of course, later in combat use. The resulting superficial steel structure - called hada - which occasionally resembles the grain of wood (mokume and itame hada), is thus more of a byproduct.
Over time, however, the various types of hada have been classified according to pattern schemes (for example, ayasugi hada, masame hada) and form an important feature in evaluating a sword.
Due to the revival of romanticism in the second half of the 20th century, the transfiguration of the European Middle Ages, the Middle East and the Far East became popular again.
Japanese culture, in particular, exerts a continuing fascination on recipients of Western culture, fed primarily by Japanese films, anime, and manga. See also Anime and Manga in Germany.
The portrayal of samurai and their sword fights, as well as duels between the manga and anime protagonists, contributed significantly to the emergence of many misconceptions, which to this day are mostly accepted without criticism.
In the last ten years, a media trend toward the glorification of Japanese blacksmithing has become apparent, which is also reflected in popular science formats - offered by National Geographic, History Channel and Discovery Channel.
Frequently, also by experts in popular scientific publications, the opinion is held that the Japanese sword represents the climax of swordsmithing in the entire history of mankind.
However, this assertion does not stand up to the archaeological, metallographic and historical sources.
The above-mentioned laminate structure of the Japanese blades is nothing unusual or unique, because even the Celtic swords of the 5th century BC (almost a thousand years before the independent iron smelting in Japan) show a purposeful welding of different types of steel.
he same is true of Damascus steel. Studies of Roman and Germanic swords (spathae and gladii) also often show complex damascus structures.
Especially the worm-bladed European blades of the early Middle Ages are hard to beat in their complexity. This is proven above all by the research of Stefan Mäder, who had experts polish early medieval blades in Japan as part of a project.
The results clearly prove that even the Saxe were made of finely fermented steel with uniform carbon distribution, composed of different types of steel, welded together (ductile core steel and high-carbon cutting edge steel) and selectively hardened.
Selective hardening was also found on late Roman spathae from the Nydam ship. Accordingly, neither laminate blades, nor refining techniques, nor selective hardening are anything exclusively Japanese or "out of the ordinary."
Near Eastern and Central Asian blacksmiths at the time possessed equally extensive know-how as their Japanese and European counterparts and used at least the same processes to produce high quality sword blades.
Swords of the same quality as the Japanese had been produced in Europe since the times of the Roman Empire, paralleling India and Persia, where crucible steel production reached a peak in antiquity.
Historically, there is no evidence of the Japanese sword's superiority to all others, nor of any special properties of the blade material.
Finally, until the middle of the 20th century, there are no scientific publications that speak of fundamentally inferior raw material and poor workmanship of historical European blades.
Historic reports concerning the forging art of the Celts (Diodori Siculi Bibliotheca historica) and Franks do not reveal any inferiority of European steel products compared to other cultures.
As early as the 19th century, it was recognized that the forging processes of European antiquity (Celts, Romans) were in principle the same as those still practiced in Japan today.
It was also possible to prove by material science that modern homogeneous industrial steel is qualitatively superior to any welded composite in purely technical terms. From the 1920s onward, scientific metallographic studies of ancient blades have been available. In this way, it can be concluded that all European blades are inferior to those of other cultures.
It can thus be concluded that all historical and modern scientific sources attest to the good steel quality and the distinct forging skills of European blacksmiths since ancient times.
The alleged poor steel quality and inadequate forging skill of European blacksmiths is basically a product of popular mass culture in the second half of the 20th century, when Japanese blacksmithing became accessible to the general public through the media.
The contrast between traditional Japanese blacksmithing techniques and the romantic notion of ancient and medieval Europeans as "uneducated barbarians" was successfully staged by the film industry and perceived as "historical" by the general public.
Even the alleged superiority of damasks or crucible steels over homogeneous dyer steels cannot be scientifically proven to this day, but has its origins in 19th century romanticism and not least in the romantic literature of Walter Scott. The myth of the inferiority of European steel production and forging technology therefore has no serious sources whatsoever.
Furthermore, it is claimed that the katana is virtually indestructible due to its soft ductile core and very hard (up to 61 HRC) edge, cutting steel and organic materials with equal effectiveness.
However, this image of the Japanese sword comes entirely from anime and the romantic transfiguration of Japanese legends. Apart from the fact that heat-treated steel of 45-58 HRC cannot cut such a steel, but at most break it, such a view contradicts the laws of physics.
There is a multitude of Japanese and European historical-literary sources that report bent, skewed, and broken sword weapons.
There are also reports of use against metal (with serious consequences for the weapon), but an ability to "cut steel like butter" or "cut through silk cloths in mid-air" cannot be proven anywhere historically, which is not surprising in view of modern tests and metallographic examinations of ancient sword weapons.
Depictions in movies, computer games, and anime in which stones, solid metal objects, or plate armor are cut in two with one blow and without significant material resistance are fiction. Considering the compressive or tensile strength and hardness of iron, steel as well as rocks, such cuts are physically impossible.
One of the exclusive attributes of the Japanese sword is its supposed phenomenal sharpness.
This seems to have been so, as it was noted during Hasekura Tsunenaga's visit to Europe in the 17th century. This claim is derived from the fact that the hardness of the katana's cutting edge usually exceeds that of the European originals (55-58 HRC vs. 64-67 HRC of the Jap. katana).
However, the hardness of the cutting edge actually has no effect on sharpness per se - this is where edge retention and sharpness are confused. In fact, lower ductility of the cutting edge steel can actually be detrimental to sharpness at the microscopic level.
The soft core and back of the blade (mune) of the katana also ensure that the weapon bends quickly under load, as this is the only way to absorb the stress and keep the hard cutting edge intact.
This also explains many nicks and bends on historical Japanese blades. With stiffer blades and higher hardness of the core, the risk of chipping at the cutting edge increases as expected when the load is too high.
The frequently cited "hardness with simultaneous elasticity" is thus a compromise and not a union of two opposing properties.
There is also the opinion that katanas are very thin compared to other swords, which leads to a steep blade geometry and thus extraordinary cutting performance.
European sword weapons of all things are often assumed to be extremely thick; possibly only because the visibly wider blades are automatically assumed to be thicker as well, or because of the fencing weapons that appear thick due to their striking edge, which are used in scene fencing and exhibition fighting.
However, the fact is that a Nihonto blade is 6 to 9 millimeters thick and this thickness hardly decreases towards the point (kissaki), while European swords are up to 8 mm thick at the blade root and sometimes only 2 mm thick in the point area.
Thus, Japanese swords are actually thicker than, for example, the original swords of the European Middle Ages.
Ultimately, blade thickness is only one macroscopic parameter of several that, together with microscopic structure, define the sharpness of a blade.
Kenjutsu, the fencing system associated with the katana, is often treated very imprecisely in popular scientific print media and TV broadcast formats.
The boundaries between Kendō, Kenjutsu, and Aikidō are usually blurred, and thus a modern sport like Kendō is often erroneously referred to as an "ancient swordsmanship."
The public's conception of Japanese swordplay is largely based on samurai movies, Hollywood depictions of the Far East, or, especially among young recipients, anime series such as Naruto or Kenshin.
Notions of a weapon's intrinsic killing potential come from computer games and have nothing in common with real blank weapon use.
Because of this tendency, and the widespread prevalence of 18th and 19th century misconceptions regarding European sword weapons, the opinion is often expressed that the katana is superior to all other swords in terms of speed because of its supposedly light weight compared to other bladed weapons.
However, considering the fact that an average katana also weighed around 1100-1200 grams like the European fighting sword (type X to XIV according to the Oakeshott classification), the above-mentioned claim remains at least doubtful. claim remains at least doubtful.
The saber (0.9-1.1 kg), the rapier (up to 1.4 kg) and the Roman-Germanic spatha (0.6 to 1.2 kg) also existed in weights below 800 grams (example: the Russian-Caucasian shashka).
Thus, the katana is rather in the middle range in terms of weight. The two-handed guidance with an average blade length around 70 cm also has its counterparts in other cultures (e.g. the European long knife).
Herewith, in reality, there are no logically comprehensible reasons for a significantly faster fencing with the katana than with other historical fencing styles.
Arguments such as the historical absence of highly developed fencing teachings and qualitative serviceable weapons among other peoples outside the Sino-Japanese cultural sphere do not correspond to the archaeologically and historically proven facts from a scientific point of view.
There are also misconceptions that go in the other direction; for example, it is often claimed that Nihontō represented purely cutting weapons and were only suitable for fighting unarmored opponents.
The fact that today almost all authentic Japanese swords are forged for sporting activities such as tameshigiri and Iaidō plays a major role in this.
The so-called Koto swords ("ancient swords," roughly speaking, made before and during the 16th century) exhibit a high degree of variability in terms of blade geometry, curvature, balance, and weight, although the basic concept of the Nihontō always remained the same.
Their primary purpose was to combat Japanese armor, which included iron and steel (e.g., helmets).
Because of this, classical Japanese swords from the period of wars and conflicts prior to the Tokugawa Shogunate are well adapted to the armor of the time, and thus are suitable for more than just cutting soft targets.
An important distinction; the katana did not emerge in its current form until the 17th century, the battle swords prior to the Tokugawa Shogunate were generally not katanas and were used in a correspondingly different manner.
The concrete field of application of the katana is very often neglected or distorted. Among other things, it is stated that the katana is ideally suited for fighting any kind of armor and can be used in almost any conceivable combat situation.
Such ideas, however, too clearly reveal the influence of modern samurai and ninja movies, which usually have nothing to do with historical warfare. Until the Edo period, samurai were primarily mounted archers, with their sword tachi used only in an emergency situation.
It was not until a decree by Shōgun Tokugawa Ieyasu that the katana, which had evolved from the uchigatana in the 15th century, was transfigured as the "soul of the samurai," with classical warfare on horseback in full armor forever relegated to the past.
The katana itself was thus from the outset a personal dueling weapon for weakly or not at all equipped opponents, which acquired its final form (mounting, polish, design) only in the 17th century.
Hereby, the katana of the 17th to 19th centuries came into virtually no contact with lamellar armor, breastplate, or traditional Ōyoroi armor of earlier times. Their alleged armor-piercing properties or universal suitability for all battlefield needs are hereby devoid of any historical basis.
In contrast, it should be noted that European swords of the High and Late Middle Ages, Central Asian sabers, and Middle Eastern bladed weapons often had to endure peak loads when fighting chain mail, plate armor, or even plate armor that could never occur with Japanese armor in this way
- cutting through chain mail or piercing plate armor at the appropriate point places very high demands on the blade material and the heat treatment of the blade.
The structure and hardening of the katana are hereby purely technically unsuitable for fighting plate armor or chain armor, this concrete relatively young type of sword (not to be confused with Tachi or Nihontō per se) served exclusively representative purposes and as a dueling weapon against unarmored opponents.
One of the most common arguments used to prove the superiority of Japanese blades is the claim that iron lobe - tamahagane - from the Japanese racing furnace (tatara) is particularly pure or consistently contains high amounts of alloying elements such as molybdenum, vanadium, or tungsten.
However, the raw tamahane from the racing furnace is a random product whose slag and carbon content can vary widely. Consequently, each piece of tamahagane is absolutely individual.
The smith's expertise allows him to select suitable pieces, which should be as slag-free as possible and have a carbon content of between 0.8-1.3%. The Japanese iron ore in the form of "satetsu" (iron sand) was of mediocre to inferior quality,
which is why the lengthy refining techniques of folding and forging to purify the steel were necessary (see Yoshihara, Tanimura). Thus, the quality of Japanese steel and the great skill of Japanese blacksmiths lies more in their ability to forge good to very good quality blades from mediocre starting materials.
This also explains why Japanese blacksmiths liked to use European export steel ("Namban-Tetsu") at the time of the Namban trade and afterwards. The quality of Japanese blades is therefore not based on the quality of the raw material as such.
As for the alleged alloying elements, they have not been found in significantly elevated amounts in metallographic examinations
. Apart from the fact that a racing furnace cannot provide the temperature required for the production of low- or high-alloy steels, modern steels do not exhibit "amazing properties" often attributed to Japanese steel by the media, despite all possible combinations of the above-mentioned elements.
The presence of molybdenum and vanadium in significantly high proportions, as well as nano-structures in Japanese steel, has actually not been demonstrated to date; it is basically a false analogy to Wootz and the role of vanadium as a carbide former, owed to less than careful media reporting.
The katana is normally cleaned and cared for in a specific order and with various utensils (provided there are no nicks, which necessitates the use of whetstones).
In the context of normal cleaning, a light wiping of the surface is sufficient, without exerting significant pressure. Areas with visible, light rust film or the consequences of saliva splashes, fingerprints, etc., can also be removed with Uchiko to a limited extent.
However, you should never try to 'repair' the affected areas quickly by rubbing them firmly. The result would be a scratched or brightly polished area and a destroyed polish.
Instead, using Uchiko of the highest quality (i.e., finely ground), the affected areas should be treated with only minimally increased pressure (compared to the treatment of the rest of the blade surface) and only briefly at a time.
Then lightly oil the blade (see below) and repeat the procedure only after a few days. This type of "repair" may well take several weeks or even months and requires perseverance and patience until the damaged area has disappeared, but this is the only way to achieve a largely polish-preserving repair.
In the case of more extensive damage or if the recommended procedure no longer helps, the only option is to repolish.
However, long-term use of Uchiko also eventually contributes significantly to polish "fatigue" due to its minimal abrading (surface-abrasive) property.
Therefore, it is better to keep the frequency of use of Uchiko for blade cleaning to a minimum. The renewal of a polish is always an abrasion process and "Togi" (Japanese professional sword polishers) are rare outside Japan.
An alternative or supplement to uchiko is high-purity ethanol (spirit, alcohol of wine, min. 90%) from the pharmacy.
After the first dry wiping of the blade with the nuguigami (Japanese paper, see above) or a piece of chlorine- and acid-free, soft cellulose, a new, clean piece of paper is moderately soaked with 90% ethanol, with which the blade is then wiped in long strokes and without great pressure.
The wiping hand is always moved along the blade from the blunt side of the blade back to avoid cuts.
Wait briefly until the alcohol has visibly evaporated and the blade is dry, then wipe again briefly with a new, dry and soft piece of paper and finally oil the blade as described below. 90% ethanol is suitable in principle for all katana steels, both historical (Tamahagane) and modern.
For valuable blades, it is advisable to test clean a small uncritical area in advance, e.g. the ji under the habaki surface, to be on the safe side.
An important note: The small area of the ji (lateral blade surface) under the habaki (blade ferrule) must always be wiped in the direction of the nakago (tang) during any cleaning, never in the direction of the blade!
This place is a dirt trap, often metal particles of the Habaki or rust particles of the Nakago (Angel) accumulate there.
Wiping in the direction of the blade then transports these onto the blade surface and causes scratches over time. When oiling, you should also treat this area rather with an extra oil cloth or with the oil-moistened fingertip (work in the direction of the tang), but not with the same cloth with which the rest of the blade body is treated.