Brass Forest Kotanto – Crossed Heart Forge

The core of this project is a high carbon blade, charcoal-forged from reclaimed steel, water quenched with clay and sharpened with waterstones, an outdoor knife that has the foundation of the Japanese sword but is 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 steel.

The subtle and rustic appearance of hammer marks on the blade and 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 hearth. A hand crafted tool for adventure that would be very much at home in the field, forest, or mountain landscape.

Forged from a reclaimed file, the narrow blade profile of the forest style kotanto is based on the tip of a classical yoroidoshi tanto and has a tapering takenoko shape with slight drop point. This blade has a subtle forged swedge along most of the omote side and a very interesting suguha hamon.

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.

Island Blacksmith: Charcoal forged knives from reclaimed steel.

The handle and scabbard are carved from local magnolia and finished with traditional fukiurushi lacquer with undertones of black to highlight the facets of the wood. A spiral forge welded hamidashi style guard and reclaimed brass sword fitting complete the handle and a natural cord wrapped koiguchi accents the scabbard. The removable peg is carved from susudake, a piece of bamboo that served for a century or more as part of the ceiling or inside thatched roof structure in a kominka, darkened and hardened by decades of smoke wafting up from the irori hearth.

The blade is just over 6″ long, the overall length is about 10.25″, and 11.25″ when sheathed. The spine at the munemachi is about 4mm thick.

Specifications

Nagasa (blade length): 156mm
Motokasane (blade thickness): 4mm
Motohaba (blade width): 29mm
Sori (curve): 1mm with slight drop point
Nakago (tang): 99mm
Tsuka (handle): 105mm
Koshirae (overall): 285mm

Katachi (geometry): hira-zukuri (or subtly kata-kiriha-zukuri), iori-mune, with ubuha
Hamon (edge pattern): suguha
Boshi (tip pattern): ko-maru
Nakago (tang): futsu, kuri-jiri, one mekugi-ana
Mei (signature): mumei (unsigned)
Koshirae (mounting): satoyama hamidashi style, issaku

Materials: reclaimed file steel, scrap iron rod, reclaimed brass fitting, Magnolia, natural fiber cord, natural urushi lacquer, susudake Bamboo

This piece is in a private collection in Manitoba.

Island Blacksmith: Charcoal forged knives from reclaimed steel.

Process

This knife began as a very old file that was pitted by rust and no longer sharpenable. The blade was forged and underwent yaki-ire at the museum forge as part of a demonstration for the Shop Teachers of Nanaimo on a professional development day. Additionally the scabbard was crafted at the museum as part of a demonstration for the Railway Days event.

This blade was forged from an old file that was beyond resharpening due to rust pitting.

There is a subtle forged swedge running most of the way along the omote side, a sort of kata-kiriha-zukuri.

Some draw filing in the sen dai (staple vise) to clean up the edge but leave the rust texture and file teeth on the upper part of the blade, finished with a polishing stone.

Adding the thin clay layer to delay the cooling of the body of the blade during yaki-ire (hardening).

The blade cleaned of clay after surviving the stressful process of yaki-ire, it has gained quite a bit of sori (curvature).

The strip along the edge is now very hard while the rest of the blade remains tough and ductile, the best of both realms.

The guard was spiral forge welded from scrap steel rod, here drifted and adjusted to complement the blade.

The spiral forge weld is visible in the surface of the guard.

Some filing to fit the guard snugly to the tang while still allowing for removal.

A slab of Magnolia is sawn into a blank to form the tsuka (handle) and saya (scabbard) and flattened inside with a kanna (handplane).

After choosing the best grain direction, the tsuka (handle) blocks are split from those for the saya (scabbard).

The inside of the halves are carefully carved to fit the nakago (tang).

The tsuka halves are glued back together with sokui (rice paste glue) and wrapped to dry overnight (yes, that is antique sword silk).

The block is planed down to dimension with a kanna and then carved to shape using kiridashi (carving knife) and planes.

A shoulder is carved to fit the ferrule and then the handle is shaped to flow from it.

The mekugi-ana (peg hole) is drilled in the tang with a hand powered post drill.

A kiri is used to drill the mekugi-ana (peg hole) in the handle to align with the one in the tang.

The mekugi (retaining peg) is carved from susudake, bamboo that has spent the greater part of a century as part of the ceiling or roof inside a kominka farmhouse, darkened and strengthened by the smoke from the hearth.

It is carved in such a way as to leave the strong grain of the bamboo’s outside wall running full length along the back edge of the peg.

The saya halves are prepared and marked for carving.

The inside is carefully carved to fit the blade and hold it snugly as best as possible despite the lack of a habaki.

Glued with sokui and wrapped to dry, wedges provide extra tension and pressure where needed.

Working on the scabbard at the Railway Days event at the museum.

Excess wood is removed from the scabbard with kanna (handplanes), from four sides to eight sides to sixteen and so on taking thinner shavings until the final shape is achieved.