It hasbeen stated that the samurai"s knife was his soul. Maybe this deepattachment had something to do with the perfect mediate of form and functionfound in the katana, together the famouscurved knife is known in Japan. Developed a millennium ago, the katana continues to be a marvel that aesthetic beauty and skillfulengineering. While many bladed tools over the centuries were designed toeither pierce or slash, the katana"stwo different varieties of steel gave it optimum attributes for both, making it ahighly functional weapon in battle. Below, follow the actions that amaster Japanese swordsmith takes this particular day to handmade what is may be the mostlegendary that swords.—Rima Chaddha and Audrey Resutek

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SmeltingsteelThe classic katana knife is fashioned only from the pure steel, i m sorry the Japanese contact tamahagane ("jewel steel"). Over 3 days and three nights, smelters using old techniques shovel roughly 25 lots of iron-bearing flow sand and charcoal into the mouth the a tatara, a rectangular clay furnace developed specifically to create a solitary batch the tamahagane. Created of carbon, the charcoal is as lot a vital ingredient in steel together a source of fuel for the furnace. The tatara will reach temperature of approximately 2,500°F, to reduce the iron ore come steel and also yielding around two lots of tamahagane. The highest possible quality tamahagane can price up to 50 times more than simple steel do using modern-day methods.

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DissolvingcarbonWhile fired in ~ high temperatures, the tamahagane is never enabled to with a molten state. This is to ensure that just the right amount of carbon will dissolve into the steel, and that the portion of carbon will differ throughout the tamahagane (between 0.5 and about 1.5 percent). Katana-makers usage two varieties of tamahagane: high-carbon, i m sorry is an extremely hard and permits for a razor-sharp edge, and low-carbon, i beg your pardon is an extremely tough and enables for shock absorption. A sword composed simply of one kind of stole or the various other would one of two people dull too quickly or be also brittle. ~ above the third night that smelting, once the tatara master break open the clay heater to expose the tamahagane, they usage the degree of ease v which the piece of newly made steel break apart to discern their carbon content.

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RemovingimpuritiesThe finest pieces the tamahagane are sent to a swordsmith, who heats, hammers, and also folds the steel repeatedly in order come further incorporate the iron and carbon, and also to draw out any type of remaining undissolved impurities, or "slag." This step is as vital as the is tedious, because if other aspects besides iron and also carbon remain in the result sword, they will weaken it. When the skilled smith has removed all of the slag, he deserve to judge the carbon concentration of the tamahagane by the degree to which it yields to his consistent pounding. One skilled has likened eliminating slag from stole to squeezing liquid from a really hard sponge.

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Forgingthe swordAfter the smith hammers all slag native the tamahagane, that heats the hard, high-carbon steel and also shapes it right into a long, U-shaped channel. He then hammers the tough, low-carbon steel, i m sorry he has shaped for this reason it will make a snug fit into the channel and also forges the two steels together. Both varieties of tamahagane are now precisely where they need to be: the hard steel forms the sword"s external shell and deadly blade, when the difficult steel serves as the katana"s core. This perfect balance of properties is what made the katana the samurai"s most durable and prized weapon.

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Coatingthe katanaWhile the katana"s body is now complete, the swordsmith"s work is far from over. Simply prior to firing the sword a last time, the paints a thick, insulating mixture that clay and charcoal powder onto the blade"s upper sides and dull ago edge, leave the sword"s spicy front edge just lightly coated. This serves both to defend the blade and also to offer it its signature wavy design called the hamon, which later polishing will certainly reveal. The swordsmith then locations the katana back into the fire to be heated to just listed below 1,500°F; any hotter and also the sword could crack during the following step.

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Curvingthe bladeNext, the smith pulls the katana from the fire and also plunges it into a trough of water in a fast cool-down procedure called "quenching." because the sword"s ago edge and also inner main point contain very tiny carbon, they deserve to contract an ext freely than the high-carbon steel at the front edge of the blade. The distinction in both the degree and speed the contraction between the two develops of tamahagane reasons the sword to bend, creating the distinctive curve. This is a tricky stage, in which as numerous as one in three swords is lost.

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Polishingthe bladeThe katana, completely forged, currently goes to a skilled sword polisher, who may spend much more than 2 weeks honing the sword"s razor-sharp edge. The meticulously rubs the blade v a series of grinding and also polishing stones, some valued at more than $1,000 each and also often passed under through families for generations. Sometimes called "water stones," these devices are frequently composed of tough silicate particles suspended in clay. As the clay slowly wears away during use, more silicate particles space revealed, guaranteeing wonderful polishing high quality throughout the life the the stone. Each consecutive collection of polishing stones includes finer and finer silicate particles and also removes less and less that the steel.

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Addingfinal touchesIn the final stage, metalworkers add a decorated safety of iron or other metals at the sword"s hilt. Next, carpenters fit the weapon through a lacquered wood scabbard, which artisans climate decorate with assorted adornments. Fashioned from yellow or exotic leathers and stones, the katana"s manage is as lot of a work-related of art together the tongue itself. Finally, the katana is went back to the swordsmith, who examines the weapon one last time. It has actually taken 15 men nearly six month to create this single katana sword. Despite fit for a samurai warrior, this knife will likely sell to art collectors for hundreds of thousands the dollars.

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