How to Appreciate Blade Quality?

Generally, we appreciate blades with the three elements.

At first shape, then steel, and then hamon.

1) Shape

You must take an over-all look at the blade first.

Seeing the shape completely is very important to appreciate blades. It should be well-ordered from the bottom of tang to the top of kissaki.

All the elements of the blade are condensed to its shape. So understanding the distinction between good shape and poor shape is necessary to know its quality. For the good shape, every line must be smooth and sharp, every surface even, and full meat is kept on the cutting surface. And the harmony of the whole shape is most important. A good shape will come from good steel and good tempering. It illustrates a sense of the smith. But it is difficult to explain the "shape" by words or images. "Good shape" doesn't mean some design of blade. It is general word used for every kind of style of blades.

2) Steel

Steel is a base of blade quality. A good steel is necessary for good shape and for good tempering effect. It is not a meaning of layer pattern. Steel is the foundation of blade quality .To appreciate a blade the steel structure is very important. To recognize the steel quality is a little difficult for beginners, but very interesting.

Japanese blades have a layer pattern caused by fold welding work. These patterns are interesting and are one of the characteristics of the blade.

(layer pattern = HADA in Japanese)

A beautiful layer pattern does not necessarily mean good steel. It is a secondary effect of the fold welding.

In Japanese blades this forge welding is not performed to create a patterned steel. The pattern develops as a bi-product of refining the steel.

This is a very big point that many overseas collectors misunderstand.

Good blade steel, in other words, has a clear colour and is made of fine particles. That comes from good material and good tempering.

Such a steel must accompany a good hamon. This doesn't mean an aesthetic hamon pattern. It means a hamon that is bright and made of fine particles

This is what the samurai of the past appreciated in a blade because behind the beauty lay a weapon they could trust with their lives.

-important-

The main purpose of fold welding work is to refine the primitive steel.

The raw material for a Japanese blade is very pure, but primitive. It contains slags and voids due to the low temperature reduction utilized by the traditional Japanese smelting process.

Blade smiths squeeze the slag out of the steel by a fold welding method. Finally, they arrive at a fine grained, pure steel block that can be used for blades. This refining work put layers in the steel as a secondary effect.

When we try to attribute a blade to an individual smith, the layer pattern becomes one of elements we use to define the smith's tradition or his personality. In the modern age, people began to appreciate the layer pattern designs as an art form.

However, what ever the layer pattern, it does not define steel quality.

Sometimes blade steels show open layers. These failed welds are detrimental to the aesthetics of the blade but they don't necessarily mean a lack of quality in the steel. Likewise, a blade with no weld failures can't be guaranteed to have good steel. Visible and attractive layer patterns do have visual appeal and I see nothing wrong with this, as long as steel quality is maintained.

Material

TAMAHAGANE and OROSHIGANE

Traditional Japanese blades are made from a pure carbon steel that is produced by the low temperature deoxidization method.

The steel is mainly TAMAHAGANE, with additions of OROSHIGANE.

TAMAHAGANE is made by the TATARA method from iron sands using plenty of charcoal. It is primitive, but very pure.

The smelt temperatures in the Tatara are low and the reduced iron doesn't become fully liquid. Because of this, other trace elements in the sands can't form alloys in the steel and are removed along with the slag.

A fresh born tamahagane billet from the tatara furnace is very big. It is the size of a calf and includes various qualities of steel.

It is broken into many small pieces, and they are surplied to smiths.

Tamahagane is very pure as a steel. But it has some slags and many voids.

OROSHIGANE is a steel that made by sword smiths themselves. By this process the smith gets

exactly the quality of steel he wants. The materials of Oroshigane are pure iron, sponge iron, electrolysis iron and old iron wares that were made from Tatara smelted iron. Anyhow eliminate non-Fe metals.

Using there own fires, and plenty of charcoal, the smiths can produce their own pure carbon steels. Simply put, Oroshigane is a smith personal tamahagane.

3) Hamon

Various types of Hamon patterns are attractive for beginners eye, but to see the quality of hamon is far more important.

Utsuri (shadow of hamon) also can be seen by this way.

Real colours come up.

Hamon is a borderline of the areas between very hardened area and not so hardened area. It can be seen as a white line in properly polished blades. The hardened area is made by the tempering work, heating and quick quenching. And the border line is an effect of the work.

Hamon is the most visible appearance of the sword. Looking at it is very interesting. Hamon is a big factor of the character of a blade. Its pattern is very attractive for beginners’ eye.

But, the pattern does not mean the quality. An aesthetic hamon pattern doesn't mean a good hamon. It is just a matter of liking. The brightness and the fineness of the hamon, not only the hamon line but also the hamon area, is a bigger criterion of the quality.

A good hamon is made of fine and bright particles.

HAMON particles, NIE and NIOI

A hamon area, hardened area of the blade, is a mass of the hardened steel cristal.

A hamon line is made of small particles of hardened steel. The particles are classified with different names by their sizes. They are roughly called NIE and NIOI.

The smallest particles are NIOI.

It is hard to recognize each particle on the hamon. The hamon pattern that made of NIOI looks like a narrow white line.

The visible particles are called NIE. It can be seen as a construction of many grits. NIE is classified into three sizes again.
1) Small particles are KONIE. It means a small nie.
2) Large particles are NIE.
3) Rough particles are ARANIE. It means a rough nie.

So the particles are classified into 4 degrees by their sizes.

nioi (smallest) => konie (small) => nie (large) => aranie (rough)
But the classification is not exactly. They are seen as combined form on the hamon.

In roughly speaking, the sizes means a temperature of the heat treatment. The steel crystals become large by heating. So the temper line made of NIOI is lower than the temper line made of NIE in the work of heat temperature. Therefore, NIOI hamon on tight steel tends to be sharp edge, and NIE hamon on rough steel tends to be tough edge.

But actual blades are not so simple. Seeing the brightness of particles is very important to appreciate blades.