It is often said that the soul of the warrior is represented within his blade to which the spirit of the maker resides there as well. I can’t help but wonder how Japanese swords are forged. As creations of craftsmen, swords are a reflection of the personality of their makers. There are dominant techniques used for creation of swords that have been passed down for generations. It is true that no two authentic Japanese swords are exactly alike.
Before one can be considered a master Japanese sword smith, it takes years of experience to become expert at this craft. The process of forging requires repetition of forging numerous blades that one can learn what material to use, how long to heat/cool the blade, how to fold the steel, how long to hammer the blade, and so on. It takes a keen sense of the nature of the metal itself as well as timing to further distinguish a master’s blade from a run of the mill, factory-produced sword.
Many modern smiths utilize a long method of repeatedly heating, folding and hammering steel for their blades. The makers at Dynasty Forge, for instance, use this process to remove any impurities from the metal of the sword and to highlight the Hada or the grain patterning on the blade). Smiths from the Imperial Forge also use this process with their Imperial Folded Sword collection to remove imperfections in the blade while assuring maximum power and flexibility.
Another distinctive technique is called differential quenching or the forging of Japanese swords. Clay is placed on the back of the sword during the cooling process. It causes the sword to have a softer edge than the blade. This pulls the blade upward, providing the distinctive curved shape of the Katana. Some sword manufacturers, like Dynasty Forge, cover the majority of the blade of some of their sword lines in clay during the heating process. When clay covers the blade then the force of the fire is on the very edge of the sword to produce maximum sharpness. Last Legend also uses clay to create hamon lines on their blades for pattern distinction and aesthetic purposes.
Sword construction is a process of using multiple layers of different types of steel or metal in the forging process. A good example is Cold Steel swords that use three layers of steel in their “San Mai III” blades for maximum flexibility in outer layers. Its outer layers help keep blade from shattering when struck while providing for maximum strength at the blade’s core. Thaitsuki Nihonto also combines soft iron and steel by hammering them into one piece, again allowing for pliability and strength.
History has it that a famous Japanese swordsmith created this traditional forging process (folding, using multiple layers, using clay for differential tempering) after his daimyo (feudal lord) lost a battle using swords he had designed without these traits. The smith realized that he needed to produce a strong blade endowed with flexibility to sustain sharp blows of the enemy and remain pliable. When we go back in history, swords then were largely comprised in a traditional heat tempering method employing only one type of steel or metal. This typically meant swords were both unwieldy (very heavy) or quick to shatter. Quite expectedly, the new brand of swords of the master smith allotted triumph of his lord winning a battle after another. The smith realized this winning combination of a softer iron/metal (for durability/lack of shattering) with a harder iron/metal (for cutting power/strength) would provide a weapon worthy of a Samurai.