Process – Forging a Mountain Kotanto

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.

Island Blacksmith: Charcoal forged knives from antique steel.
The pre-1960s (integral) cultivator tine that the starting material was cut from.
Island Blacksmith: Charcoal forged knives from antique steel.
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.
Island Blacksmith: Charcoal forged knives from antique steel.
Approaching the final dimensions.
Island Blacksmith: Charcoal forged knives from antique steel.
Forging with a thin layer of water on the anvil keeps the surface smooth and clean.
Island Blacksmith: Charcoal forged knives from antique steel.
The clay mixture will control the cooling rate of the main part of the blade during yaki-ire.
Island Blacksmith: Charcoal forged knives from antique steel.
After yaki-ire–the exposed edge has cooled quickly and become very hard, able to hold a keen edge.
Island Blacksmith: Charcoal forged knives from antique steel.
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.
Island Blacksmith: Charcoal forged knives from antique steel.
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.
Island Blacksmith: Charcoal forged knives from antique steel.
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.
Island Blacksmith: Charcoal forged knives from antique steel.
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.
Island Blacksmith: Charcoal forged knives from antique steel.
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.

Specifications

長さ/刃長 Nagasa (blade length): 124mm
重ね/元重 Motokasane (spine thickness): 5mm
元幅 Motohaba (blade width): 27.5mm
反り Sori (curve): muzori (straight)
中心/茎 Nakago (tang length): 96mm
柄長 Tsuka (handle length): none
拵全長 Koshirae (overall): none

形 Katachi (geometry): hira-zukuri, iori-mune, slight ubuha (thickened edge near the machi)
刃文 Hamon (edge pattern): suguha
帽子/鋩子 Boshi (tip pattern): ko-maru
中心/茎 Nakago (tang): futsu, kuri-jiri, no mekugi-ana
銘 Mei (signature): mumei (unsigned)
拵 Koshirae (mounting): none

Materials: pre-1960’s cultivator tine, antique copper habaki

This piece is available online.

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