Kominka Field Kotanto – Crossed Heart Forge

This project was a unique opportunity to work with legacy materials to craft a useful tool that is already an heirloom. A charcoal-forged blade, water quenched with clay and sharpened with waterstones, an outdoor knife that has the foundation of the Japanese sword, finished in the simple and humble style of farming and foresting tools of centuries ago.

Satoyama are the managed forest areas that border the cultivated fields and the mountain wilds in Japan. Historically they provided soil nutrients, firewood, edible plants, mushrooms, fish, and game, and supported many local industries and crafts such as farming, timber construction, and charcoal making. The interaction of forest, arable land, wetlands, and streams are an important component of the satoyama landscape.

Island Blacksmith: Charcoal forged knives from reclaimed files.

A subtle and rustic appearance with hammer marks left on the blade, hand-carved wooden handle finished with natural urushi lacquer made from tree sap, reminiscent of hand-hewn beams in a kominka farm house that are darkened by years of smoke drifting up from the irori cooking hearth. A tool for adventure that would be very much at home in the field, forest, or mountain landscape.

Forged from a reclaimed file that belonged to a client’s great-grandfather, the blade profile of this field style kotanto is inspired by a kamakura sword and has more pronounced belly with slight drop point. The temper of this high carbon steel blade has been left relatively hard in order to hold a keen edge for tasks such as wood carving and hand work. This particular combination of steel and heat treatment is well suited to users who require a good edge and are willing to take care of it.

Island Blacksmith: Charcoal forged knives from reclaimed files.

The tang is constructed in a similar manner to a Japanese sword requiring only a single bamboo peg to hold the knife assembly together. In addition to the sense of beautiful simplicity, this design allows the knife to be taken apart for cleaning, polishing, detailed cutting tasks, or major resharpening work.

The handle and scabbard are carved from local magnolia, reinforced with cord wrap, and finished with traditional fukiurushi lacquer to highlight the facets of the wood. The beautifully coloured copper seppa/guard was made from a scrap of tubing sourced from the same workshop as the file, and most of the stages of the project from steel to copper to wood involved shaping with other files from the same location. The removable peg was carved from seasoned bamboo from Japan.

The blade is 3.5″ long, the overall length just under 7.25″, about 8.25″ sheathed. The spine at the munemachi is about 5mm thick.

Specifications

Nagasa (blade length): 89mm
Motokasane (blade thickness): 4.75mm
Motohaba (blade width): 26mm
Sori (curve): uchizori (drop point)
Nakago (tang): 75mm
Tsuka (handle): 97mm
Koshirae (overall): 212mm

Katachi (geometry): hira-zukuri, slight iori-mune
Hamon (edge pattern): suguha
Nakago (tang): futsu, kuri-jiri, one mekugi-ana
Mei (signature): mumei (unsigned)
Koshirae (mounting): satoyama kominka style aikuchi, issaku

Materials: reclaimed file steel, Magnolia, cotton cord, copper pipe scrap, natural urushi lacquer, Bamboo

This piece is in a private collection in France.

Process

Forged from a reclaimed file that belonged to a client’s great-grandfather.

SNCF is the French Railroad, this file was used in a workshop repairing small parts of trains three generations ago.

The file itself was made in France and appears to be marked TALABOT DUTEIL.

At the client’s request most of the file teeth were removed, just a hint was left where the tang will be.

The rectangular sunobe preform determines the length, width, tapers, and allocates steel for the tang and blade.

After forging the profile and edge are smoothed by drawfiling, using the rest of the file that the blade was forged from.

Applying the clay mixture in preparation for hardening using a natural clay yaki-ire technique.

Once the clay is dry the edge is heated to critical temperature and plunged into water.

Successfully hardened using a natural clay and water yaki-ire technique.

Removing the clay mixture and testing for hardness and straightness.

Cleaning off the fire scale and checking the location of the hardened hamon area on a natural stone.

Angled lighting reveals a nicely defined sweeping suguha hamon with dramatic turnback at the tip.

A view of the peaked spine (iori mune) and distal taper.

A piece of reclaimed copper pipe, also from the grandfather’s workshop, flattened for a seppa washer. The opening is filed to match the tang and the edge is textured using another of the files from the workshop.

Magnolia wood is carved to fit the tang and blade precisely and the halves are glued back together with sokui (rice paste glue). The carved surface are finished with several layers of natural urushi lacquer.

The koiguchi (scabbard mouth) is slightly dished to allow a better fit when closed.

A mekugi peg is carved from seasoned madake bamboo and the knife is ready for assembly.

The channel for the cord wrap on the handle was formed by a small square file also from the same workshop. Also note the nice view of the remaining file teeth forged into the tang.

The handle and scabbard were finished with a kiridashi knife and kanna, Japanese handplanes.