- by Lin
- January 6, 2024
- Katana info
Traditional Japanese katana swords often have high collectible value and require experienced swordsmiths to spend months crafting them. Tamahagane is the traditional Japanese steel used to forge katana blades. If a katana is not made from Tamahagane, its value decreases greatly. As Japanese swords gain popularity worldwide, Tamahagane and katana forging methods are seen as unique traditional Japanese culture. We will outline the steps to forge Tamahagane into a katana blade. Let’s begin.
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1. The swordsmith first heats the refined Tamahagane blocks using charcoal to red hot and hammers them. Older swordsmiths may use power hammers as they cannot swing a hammer for long time. This step aims to hammer Tamahagane into the shape a ironplate.
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2. After forging into an iron plate, it is quickly cooled in water to increase hardness and make it easier to break. The Tamahagane is then shattered and neatly stacked on a steel plate.
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3.The fragmented Tamahagane and steel plate are wrapped together in a wet paper. Unburnt straw ash is added to increase carbon content. Mud slurry is then applied on the surface before heating in a furnace.
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4.After heating in the furnace for 30 minutes, the Tamahagane is power-hammered. The steel blocks are folded and hammered together. Straw ash and mud slurry are reapplied before reheating and further hammering. This continually combines the iron and carbon, removing impurities and “slag”. This process is repeated patiently.
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5.The fire temperature must be maintained above 800°C during forging.Once impurities are hammered out, the swordsmith uses a power hammer with water spraying to elongate the steel block, then hand-hammers the blade shape and files it into a “near-ideal” .
6.After washing and drying the blade, the next step is also very important.
7.This step is called clay tempering.
Clay mud is applied on parts of the blade that do not need high hardness. The blade is then heated to a specific temperature. When the red-hot blade enters water, the exposed sections rapidly cool while the clay-covered parts cool slower.
This creates differential hardening with harder and softer sections. The blade has high hardness but retains toughness. The hamon pattern is also produced.
8.The clay-covered blade is reheated, with careful positioning and fixtures.
After the long process, the blade is removed from the charcoal and rapidly cooled in water. The post-quenching blade has a clear ringing sound, with internal structure changes.
9.Finally, Inspect the blade, clean and polish and sharpen it on a blacksmith sharpener.
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There may be many difficulties behind the forging of a katana, which also determines the precious value of the katana and its spiritual art.