Process – Forging a Sunnobi Forest Tanto

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 sunnobi (overlength) tanto in the forest 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 starting point as a lengthwise half of a pre-1960s (integral) cultivator tine.
Island Blacksmith: Charcoal forged knives from antique steel.
After the tine has been straightened the sunobe (preform) is forged with all tapers and proportions in place.
Island Blacksmith: Charcoal forged knives from antique steel.
During the hizukuri stage the peaked spine is forged in first, followed by the bevels.
Island Blacksmith: Charcoal forged knives from antique steel.
After the final heat for the forging stage the steel is heated evenly to normalize, removing any stresses remaining from forging.
Island Blacksmith: Charcoal forged knives from antique steel.
After filing the notches and the spine some additional adjustment is necessary along the bevels.
Island Blacksmith: Charcoal forged knives from antique steel.
The bevels are filed slightly along the edge to clean them up before hardening.
Island Blacksmith: Charcoal forged knives from antique steel.
After a final round of normalizing again, heating to an even temperature and then cooling slowly in air.
Island Blacksmith: Charcoal forged knives from antique steel.
Preparing the mixture of charcoal, clay, stone powder, and water.
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, the blade has gained some curvature.
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 clay is cleaned off, the hardness checked, and the blade is tempered slightly over the flames.

Island Blacksmith: Charcoal forged knives from antique steel.

Island Blacksmith: Charcoal forged knives from antique steel.

Island Blacksmith: Charcoal forged knives from antique steel.

Island Blacksmith: Charcoal forged knives from antique steel.

Island Blacksmith: Charcoal forged knives from antique steel.


Specifications

長さ/刃長 Nagasa (blade length): 310mm (10.2sun)
重ね/元重 Motokasane (spine thickness): 6mm
元幅 Motohaba (blade width): 30mm
反り Sori (curve): 2mm, slight koshizori
中心/茎 Nakago (tang length): 107mm
柄長 Tsuka (handle length): none
拵全長 Koshirae (overall): none

形 Katachi (geometry): hira-zukuri, iori-mune
刃文 Hamon (edge pattern): suguha (with mizukage)
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: vintage cultivator tine steel

This piece is in a private collection in Hawaii.

Comments are closed.