This blade was forged and underwent yaki-ire at the museum forge. It began as a pre-1960s (integral) cultivator tine used by a farmer a generation or more ago. It is a kotanto in the mountain pattern, charcoal-forged and water quenched with clay, a satoyama style outdoor knife that has the foundation of the Japanese sword.
The pre-1960s (integral) cultivator tine that the starting material was cut from.
During forging, a comparison with the other (lengthwise) half of the tip of the cultivator tine it started as, which later became a forest tanto.
Approaching the final dimensions.
Forging with a thin layer of water on the anvil keeps the surface smooth and clean.
The clay mixture will control the cooling rate of the main part of the blade during yaki-ire.
After yaki-ire–the exposed edge has cooled quickly and become very hard, able to hold a keen edge.
The area protected by the clay layer cools about half a second slower as it hits the water and remains in a tough, ductile state.
The hardened hamon area is clearly visible along the edge after soaking in vinegar water to remove remaining forge scale without disturbing the hammer texture.
The blade geometry is roughly completed and ready for its final sharpening after the mountings are complete. The small unsharpened portion near the hamachi is called ubuha (original edge), which disappears slowly as the blade is sharpened many times.
The antique habaki came from the collection of a sword restorer and is likely Edo period (~1600-1800) but may be older. The specific proportions are those that would usually be found on large tanto.
Habaki make the crafting, fitting, and maintenance of the scabbard mouth much easier than when relying on the friction of the blade alone. Usually they are made to fit a blade but in this case the blade was carefully crafted to pair with the antique habaki.
