Kuromatsu Aikuchi Tanto

The Kuromatsu tanto with koshirae is named for a species of Black Pine (黒松) that grows near the seaside in Japan. The bark changes from grey to black as the tree matures and ages, symbolized by the colour and contrast of the smoother texture of the blade with the leathery texture of the darker scabbard.

Designed around the concept of an exploration in texture and form along with Kuromon Aikuchi Tanto, this piece has roots in ancient samurai aesthetics and inspiration from the natural world. Mounted in a gentleman’s koshirae with slim styling and the lines of an older piece, it suggests certain elements of tachi mountings.

One of the elements of traditional Japanese aesthetics includes the appreciation for the natural process of wear and decay. Historically, this led to the creation of new items that appeared to be aged or rugged and had elements of imperfection and asymmetry, hearkening back to ages past and honouring materials and objects that bear the marks of longevity.

This tanto is forged from reclaimed shear steel from a horse-drawn carriage leaf spring, housed in a streamlined aikuchi koshirae crafted entirely with hand tools from local Cypress driftwood, and finished with black ishimeji style urushi lacquer. The blade was hand forged in a charcoal fire, shaped with files, differentially hardened using traditional water quench yaki-ire, and polished by hand with water stones.

In keeping with the textural theme, the unusual blade polishing style reveals a strongly textured hada with remnants of the original weathered surface, revealing the blistery internal texture and flowing layers of the forge-welded shear steel. The mostly suguha hamon has a mountain peak as well as some interesting external activity including tobiyaki.

The handle and scabbard are hand carved from local Nootka Cypress driftwood, habaki forged from copper bus bar, and silver scrap combined with a forged copper washer and bamboo for the mekugi. The habaki was finished with a texture hammer rather than filed to final shape. From start to finish, the mountings for this tanto were created with hand tools using traditional techniques.

The exterior is finished with a leather textured natural urushi lacquer surface made with the crushed iron oxide reclaimed from discarded kairo, Japanese hand warmer packs. The copper and silver mekugi is shaped like a stylized iron kugikakushi (釘隠), a large nail cover found on a traditional castle door or gate, and is a symbol of protection.

Blade construction is muku with a hira-zukuri profile and an iori mune. Though only recently mounted, it is the first full sized tanto I forged as well as the first from shear steel. The blade is approximately 8.25″ long, overall length is around 13.25″, and the overall length when sheathed is about 14.5″. Accompanied by handmade reclaimed silk obi storage bag, and a full colour 22 page hardcover photo book documenting the process.

Specifications

長さ/刃長 Nagasa: 6 sun 8 bu 8 rin (208.5mm)
元幅 Motohaba: 8 bu 7 rin (26.5mm)
重ね/元重 Motokasane: 1 bu 8 rin (5.5mm)
反り Sori: uchizori
中心/茎 Nakago: 3 sun 3 bu 5 rin (101.5mm)
柄長 Tsuka: 3 sun 7 bu (112mm)
拵全長 Koshirae: 1 shaku 2 sun 1 bu 4 rin (368mm)

形 Katachi: hira-zukuri, iori-mune
刃文 Hamon: ko-notare with mountain peak becoming hoso-suguha, tobiyaki
帽子/鋩子 Boshi: ko-maru
中心/茎 Nakago: futsu, kuri-jiri, one mekugi-ana, signed near the tip
銘 Mei: hot stamped katabami-ken kamon
拵 Koshirae: ishimeji aikuchi

Materials: Century-and-a-half-old horse carriage spring shear steel, copper electrical bus bar, silver scrap from local miners in the Congo in the ’80s, copper lightning rod cable, driftwood Nootka Cypress, iron oxide from reacted kairo, natural urushi lacquer, braided silk scroll cord

This piece is in a private collection in Alberta.

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques

Process

Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
The raw material for this blade spent more than the last century as a leaf spring for a horse-drawn carriage. It is rare to come across this type of steel and is a treasure to find. It is a type of steel called “shear steel”, predating the bessemer process and blast furnaces. The deep pitting on the surface from decades of weather will mean a lot of polishing time and less steel to work with so forging must be done very accurately.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
forging to shape. above is a kata template of a historical blade for inspiration, below the raw material for size comparison.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
filing the mune (spine) and profile to shape.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
the first blade to be stamped with the new katabami-ken komon, it is also the first shear steel tanto and the first full-sized tanto forged.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
clay applied in preparation for yaki-ire, hardening the edge of the blade.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
the habaki rough shaped and prepared for silver soldering in the charcoal forge.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
the handle and scabbard are glued with rice paste and wrapped tightly until dry.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
the century-or-older horse carriage spring steel shows its layers and some surface tekkotsu. the habaki is forge-finished with a texture hammer, not filed.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
giving some character to the slimline koshirae starting with the handle.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
carving the tsukigata groove on the omote side.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
carving a variable-angled centre line to highlight the unique tip shape but blend with the oval shaped handle cross section.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
kurikata carved from local oceanspray ironwood.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
the keyway channel in the saya is slightly narrowed so it tightens as it slides into place.
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
urushi lacquer stages 4 to 7…saturate and sand the filled areas, apply a base layer of raw natural urushi and build up and polish the black koiguchi accent…
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
urushi stages 8 to 12…creating a stone-texture surface using expired kairo (hand warmer packs)…a fresh layer of natural urushi is sprinkled with the reclaimed crushed iron oxide, the excess brushed off and lightly sanded when cured, and a thin layer of urushi brushed on to saturate and seal…at right freshly sprinkled, left after the first saturation coat…the urushi reacts with the iron oxide to turn it from red-brown to black…
Island Blacksmith: Charcoal forged nihonto made from reclaimed and natural materials using traditional techniques
forging the silver dome and fluted copper washer to crown the bamboo mekugi peg

3.03022 cm
= 0.1 shaku(尺)
= 1 sun(寸)
= 10 bu(分)
= 100 rin(厘)

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