Big Tachi

blade length 91.7cm, curvature 2.0cm, thickness at the base 1.0cm, width 3.6cm

This is a long and heavy sword. We think it is koto, but not sure about its exact age.

The steel is a flowing wood grain layer pattern. The steel of the cutting edge and the body are different. The steel near the cutting edge is clear, the steel of the body is dim. It is interesting to study the difference of jinie (steel particles) between the body and the cutting edge.

The hamon is neat suguha (straight pattern) made of konie (small particles) and some nie (large particles). It is bright enough almost through the blade. But a part near the middle of the blade length, the hamon line becomes dim in about 5cm. The body steel runs close to the hamon line at the place.
The hamon in kissaki is a large round pattern with sweeping pattern of large particles (nie).

Freehand sketch that suggests the steel construction

In the sketch, the light blue is a mild steel, and the deep blue is a hard steel. The steel construction maybe two blocks or kobuse, constructed with a hard steel around the cutting edge and mild steel for body. (=> steel construction)
Shinogi-ji is mirror finish, so we can't see how the steels run around kissaki. The part where the mild steel touches to the hamon, the hamon particles become dim. The hamon area is still bright because the edge is made of hard steel.
This kind of steel construction is common on Hoju school and Naminohira school. Usually Hoju blades have a hamon pattern of Choji or Komidare. Suguha pattern is more popular on Naminohira blades.

When we were making the sketch, we found a crack at the kissaki. It is a serious flaw. I am sorry we had overlooked it.

The hamon is bright, so the steel quality is good enough. But the hardening work was effected too much at the kissaki against that good steel.

The tang has no signature.

The habaki is gold foiled.

The shirasaya is a little damaged at the throat.

830,000.yen (consignment)

HBTHK paper is added. It attributes the smith to Naminohira school. The rank of paper is Hozon Token.


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