A single yanagi knife requires at least four skilled craftsmen and two weeks to create. Even top knife companies can only produce knives at the rate of ten to twelve pieces per day. The knife making process is divided into four distinct stages: forging, blade making, handle crafting and assembling. A skilled craftsman conducts the blade through many different steps before it is passed on to the next craftsman. The number of steps varies from knife to knife according to the shape of the blade, the type of materials used, as well as the finishing procedures required. A top-grade knife undergoes upwards of fifty different steps. The following pictures highlight the complex process of making traditional kasumi style knives.
1. Hand hammering to shape the carbon steel core of a kasumi knife.
2. A high-carbon steel core is attached to a soft-iron jacket (Kasumi method).
3. Shaping the red-hot blade with a belt hammer and removing ash with a rice straw brush.
4. Trimming the blade on a mechanical cutter.
5. Tempering: The blade is covered with clay which protects it from sharp changes in temperature.
6. Quenching: The blade is quickly cooled in a water bath to ensure hardness.
7. Honyaki knives: The spine of the blade is coated with clay, and then it is reheated and slowly cooled. This process increases flexibility and creates a beautiful and distinctive hamon pattern on the blade.
2. Edge Crafting
1. Craftsman uses a rough wheel to sharpen the knife.
2. Smoothing the face of the blade.
3. Buffing the knife on a fabric-covered wheel.
4. Precision sharpening on a wooden wheel.
5. Using a wooden wheel to create the kasumi or "haze" finish. Notice sharpening powder and water spigot at left.
6. Final hand sharpening using natural water stones.
3. Handle Making
The handle craftsman chooses raw wood for the grip, and material such as water buffalo horn for the ring caps.
1. Handle is hand-turned on a lathe.
2. Fitting the collar.3. Ho wood handles with water buffalo horn collars ready for assembly.
Final assembly of a traditional knife includes numerous steps such as stamping the hand-made blade with an insignia, fitting the blade to the handle, and finally, balancing the knife. The handle is slightly burned at the point where the blade and handle meet to help prevent corrosion.
1. Tang (Nakago) is heated and inserted into handle.
2. Blade is driven firmly into handle with a mallet.
3. Company brand and insignia are engraved on blade.