THE ART OF HOW JAPANESE SWORDSMITHS CRAFTS LEGENDARY KATANAS FROM SAND
From ukiyo-e prints to origami, Japan has an incredible variety of traditional artforms. One such artform is sword smithing, a time-consuming process that produces swords like the legendary katana. The fact that these swords are made of sand, which may seem counterintuitive, makes their construction so labor intensive.
Japan, along with New Zealand, Indonesia, and the United States, is one of several regions with iron sand deposits. For centuries, Japanese swordsmiths have melted iron sand, or tamahagane ("jewel steel"), with charcoal in large clay furnaces known as tataras to make katanas. During this stage, swordsmiths must carefully monitor the temperature of the tatara while also ensuring that there is enough charcoal and iron sand in the furnace. This smelting phase can last several days and requires constant supervision. As a result, the art of swordsmithing has traditionally been reserved for those with exceptional patience, dexterity, and command of the materials at hand.
"Forging a Japanese sword is a subtle and careful process," says Edward Hunter in an essay for the Metropolitan Museum of Art. "[It's] an art that has evolved over the centuries in response to stylistic and aesthetic considerations as well as technological improvements." After the smelting process is completed, the best tamahagane pieces are chosen from the tatara. A swordsmith repeatedly heats, hammers, and folds the steel to homogenize the carbon and iron while removing any remaining imperfections or impurities. The folding also creates the patterns known as jihada on katana blades.
Preparing the sword's edge is often regarded as the most important yet difficult aspect of swordsmithing. The blade is first coated with yakibatsuchi, a mixture of water, clay, and ash, among other ingredients, and then transported to a forge room lit only by glowing coals. Here, the swordsmith meticulously heats the blade. "As the temperature rises, the crystal structures within the metal start to change. The smith closely monitors the colour of the glowing blade, and once the critical temperature is reached, the sword is quickly quenched in a trough of water," Hunter explains.
The steel changes to austenite while heating the blade, and then to martensite, the hardest type of steel, when quenched. Wherever yakibatsuchi is applied, the blade retains a level of flexibility and softness, resulting in the ideal katana sword. Finally, blades are polished with water stones, resulting in a finer and sharper finish. The method of smithing katana swords has largely remained unchanged, and given their highly specialized nature, it is not surprising that these swords have long been regarded as the souls of samurai. Perhaps this belief stems from the magic of witnessing soft sand transform into razor-sharp yet beautiful weapons.
