New Sword 3
Challenge to make "Honjo Masamune" by kokaji
Recently I heard the story of missing sword "Honjo Masamune".
That brought me an idea to make a copy of the sword, since I live in a
village next to "Honjo" city. It is a kind of joke, but may be
interesting to report the work of copying Soshu style.
- At first, what is Soshu style? -
Shape : There is no typical style in Soshu tradition, but it depends with the period.
Steel : It is famous that the steel of Soshu blades are mix forging. That
means hard steel and mild steel are mixed.
When the Kamakura government became weak around the beginning of 14th century,
they no longer had power to invite master smiths from the west Japan. That
is the background of developing Soshu style. And probably, lack of good
steel as material also would be caused. The furnace in the western Japan
had a system to be specialized to make hard steel mainly. On the other
hand, that in the eastern Japan was not so, and it made various kinds of
iron those are soft steel, hard steel, and cast iron. In the east Japan
there are many cast iron Buddha statues instead of bronze ones in the west
Japan. The fact may illustrate that cast iron is more popular in the east
Japan than in west Japan. In that situation, smiths in Kamakura city tried
to create good steel by the method of mix forging. Mild steel can be harder
by adding some amount of too hard steel. Cast iron is too hard (brittle)
to forge by hammer, but it can be used by smith through Oroshi-gane method.
Mix forging is common way to save good steel (proper hardness for edge).
But still, the steel of Soshu blades doesn't look so sensitive comparing
with good Bizen blades in the same period. Then, those steel have to be
heated and quenched from higher temperature to get proper hardness on edge.
Such work makes the steel crystallization larger.
Steel construction : I have studied many Soshu blades, so-called "Soshu
style" blades, and fake ones. I studied several Masamune in museums,
but I have never studied real Masamune in my hand. All of my Masamune in
my hand were no signature. And so were Sadamune. Studying real Soshu blades,
all of them have the wrapping style in steel construction. It is kobuse,
makuri or some style like that. On the other hand, most of "Soshu
style" blades or fake blades have three layers style (sam'mai, hon-sam'mai,
or like that). It is strange. It is Mino style in fact.
Hamon and utsuri : As I mentioned, the hamon is made of large particles
what is caused by high temperature heating at the hardening work. The hamon
pattern is straight or choji. And sometimes other patterns also are found.
But it is difficult to distinguish natural activity and intentional design.
Anyway the hamon pattern is not well ordered because of high temperature
heating. It looks active for peoples eye. The utsuri is not very clear,
but still exist. Sometimes it is clear as shirake pattern. Unfortunately,
it is difficult to research utsuri in the blades with modern polishing.
Such a polishing work emphasizes the layer pattern to show it more Soshu
- About Honjo Masamune - (Information from some books)
Blade length 65.2cm
Shape : shinogi-zukuri style, two surface back, wide blade with thin thickness,
long kissaki, narrow shinogi-ji, high shinogi line.
Steel texture : small wood grain layer pattern is dense, fine steel particles,
chikei (by mix forging?).
Hamon : made of small particles (ko-nie), its pattern is O-midare and ko-midare
with jumping hamon, kinsuji, ashi.
Tang : O-suriage (no original tang remains), end is kengyo shape, 1 peg
There is one big nick on the edge at the lower part of blade, and several
smaller nicks on the edge and on the back.
- Forging -
Select the steel
I selected the steel pieces that come from the lowest priced tamahagane from NBTHK. Those include uneven hardness in themselves. It may be close to the situation of Soshu smiths in the end of Kamakura period.
For the outer steel (in Kobuse style), I picked various hardness of steel
pieces, and put on the forging handle.
The outer steel is forged out after 15 times fold'n welding. It is cut
from the handle and still covered with ash.
Outer steel for Kobuse style construction
For the core steel, a little milder steel is selected, and start fold'n
On the work of 8 time folding
The core steel is forged out after 14 times folding.
And then, the outer steel and the core steel are welded to one steel block
in Kobuse style.
On the half way of drawing out
It is drawn out to the blade length.
Shaped by hammer work with fire
Shaped by plane and files
Preparing for hardening work, clay is put on the blade. And dry.
Full moon in the sky and no wind. It is a good night for hardening work.
Just after quenching. The blade got bent by the quenching work.
Remove the clay, and fix the bent
Of course, this blade has fumbari. Because I suspect the original shape
of "Honjo Masamune". So the blade length also is 77 cm.
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