The Japanese Sword
Forging Process - Part II

The forging process of real Japanese swords

Forging the blade

There are 2 main goals involved in the Japanese sword forging process. First, in order for the Japanese swords to maintain its sharpness, its edge must be hard. The blade’s metal must also be flexible in order to absorb shock. The way to create a metal that is both hard and flexible at the same time was figured out centuries ago and is still in use today.

Heat-tempering the sword’s leading edge, a process called Hamon, produces the real Japanese sword’s most notable and most highly sought after visual characteristic: the undulating line, or wavelike appearance, that runs the entire length of the sword edge. This characteristic that is unique to every Japanese sword edge is the end result of the way the metal has reacted to the intense heat to which it has been subjected.

To achieve this effect, as well as the sharp edge, the smith first creates a clay mixture of ash, water, clay and other ingredients. A thick layer of the mixture is applied to the spine side of the blade and the layer is thinned the closer it gets to the blade edge. All but the blade’s edge will be encased in this clay mixture.

This clay mixture coating is actually what helps control the amount of heat the different parts of the blade receive. As the sword blade’s metal is heated over red-hot coals, the crystalline structure of the blade’s metal undergoes change, and the metal produces a milk-white pattern.

A number of different patterns can be achieved, and the smith can control the pattern’s outcome by varying the way the clay mixture is applied to the metal. The resulting edge patterns have different names including Suguha which corresponds to a hamon that is very straight. A line with a zigzag pattern is referred to as a sambonsugi.

As soon as the metal reaches the appropriate temperature, which is determined by visual inspection, it is removed from the heat source and immediately immersed in a trough of water. Immersing the blade in water to cool, while the clay coating is still intact, is what changes the composition of the metal.

The metal beneath the thickest part of the mixture cools more slowly and results in a composition that is softer and more flexible. The edge, on the other hand, cools very quickly which results in a very hard composition. Remember, this is the ideal combination for a real Japanese sword blade. The smith will then inspect the sword and only if it meets his high standards will the sword be passed on to the final stages.

Polishing and mounting

Hand-polishing is what gives Japanese swords their mirror-like appearance. It is also what helps to bring out the blade’s unique characteristics. In particular, polishing brings out the intricacies of the hamon and the jihade, which are the focal points of the sword.

Polishing real Japanese swords takes years to learn and perfect. Those with the appropriate sword polishing skills typically will spend up to 30 hours painstakingly polishing each blade to perfection. Japanese sword polishers use a variety of graduating stone grits and an ample quantity of water to sharpen and shape the blade. Polishing helps bring forth the beautiful, one-of-a-kind crystalline pattern that is so desirable.

Since today’s Japanese samurai sword is hand-crafted more for pleasure than for necessity, the final step is to mount the sword so that it can be admired by all.

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