Flaws of blades
 
To study the flaws of blades is not enjoyable. But to know the meaning of the flaws is useful to recognize the quality of blades.
Many books explain about the flaws of blades how they are found, but they do not explain how serious they are.
Now let's study about the flaws how bad they are for the quality of blades.
 
Open layer (kitae-ware, in Japanese)
This kind of flaw is the easiest to be found. It is not good for its visibility. But in most cases, it is not so serious as it looks like. It is only a trouble for eyes.
A small flaw from fold welding work does not make the quality of the steel down. No kitae-ware does not mean good steel. We have to see the colour and brightness of the steel (in other words, the condition of the steel particles) to know its quality.

Sometimes, a thin open layer becomes a blister (fukure in Japanese). Unfortunately it looks so bad for eye. It is a pitiful flaw.
A blister in a newly forged blade.

A blister on an old blade.


 
Rusty dimple (kuchikomi)
Sometimes deep rust leaves a dimple on blade, even after a completed polishing work. It is bad for beauty of the blade.
But a healthy blade with some small dimples is far better than a poorly shaped blade. A careless grinding to remove deep rust is the worst way of work. We have to keep the full meat on blade surface.

In old days, sometimes such a dimple was filled with red lacquer to stop rusting.
Of course the rust in the dimple has to be cleaned before the lacquer work.
 
Inlaid steel (umegane)
A different steel is inlaid in blade surface like a small applique.
It includes a serious problem. Because it does not come from any failure. It is produced by dishonest will.
 
When there is some open layer or rusty dimple on a blade, some kind of people want to mask it.
Then he carves a ditch bigger than the opening or the dimple on it, and patches other steel into the ditch and strangles them to make good fit. A skilful work makes it a little difficult to be found.
This does not fix the flaw. In fact, the steel is damaged by spreading the flaw. Rust is growing at the bottom of the patched steel. After some times of polishing the umegane will be taken off and a large hole is left.
Serious sword lovers do not like such work that tricks beginners' eye and destroys blades.
 
Be careful, because some books introduce this method as a way to repair flaws.
 
Tempering cracks (yaki-ware)
This kind of flaw is most terrible. Some of them are really bad. It is a little difficult to be found. It is thinner than a hair line, but sharp and deep. This crack appears in the hamon area by a mistake in tempering work.
It has some different types. (Do not confuse an open layer in the hamon area to a tempering crack.)
 
 
<= This type is most terrible.
 
 
 
  <= This type is specially called "hagire".
This type of crack does not come from only tempering failure, sometimes a hard back attack can make such a crack too. I don't know why, but hagire is most hated in all kinds of flaws at market. In fact, it is not the most terrible flaw in all kinds of them.
 
In the current market, collectors don't mind tempering cracks seriously except for hagire. I have seen some number of Juyo blades that had serious tempering cracks. "Juyo" is a title that is authorized by NBTHK. They connived the cracks.
 
speaks an episode about a tempering crack.
When I was an apprentice in my teacher's work shop, one day my teacher tempered a spear that had a diamond section. Then I polished it with a rough stone to see the hamon. That was a fine suguha, and there was a sharp crescent line at the point.

My teacher took the blade to see the result and said "No good".
I asked him what was the reason of "No good"?
He pressed the tip to concrete floor, instead of an answer.
Not hit, just pressed.
The tip was broken easily, and he said me "Look".
The shape of the removed piece was as sharp as a piece of ice.
It was so nice that I wanted to keep it.


 
Poor steel, Steel cracks (shinae)
It is a steel including much of slag, rough welding.
The worst is a steel that has cracks by itself. The steel is not strong. We call such cracks "shinae" in Japanese.


Cracks on the blade surface.


Cracks on the back surface.

 
On the other hand, there is a similar appearance called "mukade-shinae". It appears in blade surface like wrinkles, not cracks.

It is not a flaw. When a blade is hardly bent and straighten again, it appears on the blade surface. It is very thin wrinkles on the steel surface, so it can be removed by sometimes polishing.
 
Poor hamon, No hamon
A dark hamon means a mild cutting edge. But too hard cutting edge is not good. Such a hamon looks like a mirror.
To see the brightness of hamon area is important.

When a blade meets an fire accident, the hamon disappears by burning out. (=> HAMON)
(=> A blade in fire accident, sword32)
 
On some old blades, the hamon is vanishing near the tang as original. It is not a problem at all.
 
Fake hamon
Some polishers forge a fake hamon on blade that has no hamon.
Some of them are so skilful that is difficult to discover the trick by a beginners eye. Some is a part of hamon, and some is all the hamon. (=> fake hamon)
 
Being tired (tsukare)
The shape has been broken by much grinding.
Sometimes the hamon was worn out by too much grinding.
 
Re-tempering (yaki-naoshi, saiha)
When a blade has been burned out by the fire, it is tempered again to recall its utility. But the originality of the blade never come again. So the value as a piece of art disappears, even if the blade has a good signature.
It is difficult to recognize if the blade was re-tempered or not only by looking at the blade surface. To research both the tang and the blade is necessary to think about it.
 
Next is an example of the case of a shortened blade.
If the signature is genuine, this starting of hamon means re-tempering.

 
The vanishing of hamon toward the tang is correct. This blade was not re-tempered.

Step-tempering (yaki-tsugi)
It is a kind of re-tempering.
Kissaki is the place what works most hardly in the blade. So some blades are worn out there. Sometimes such blades are re-tempered only around the kissaki. But the new hamon never connect to the original hamon. Some part before the new hamon is burned out by the heat of the tempering work. So, good(?) polishing is necessary to mask the inefficient part.
The new hamon must be followed with mizukage at the start of it.

 
speaks an episode about Mizukage.
I was shown an old Naginata by a customer. It is very old, may be from Kamakura period or Nambokucho period, but very healthy with its meat. It is a little shortened.
The owner was proud of the blade. But I have found that the hamon is a step-tempering, above the monouchi is a re-tempered new hamon. The owner was disappointed with that. Sometimes we find such work on old blades.


The original hamon disappears before the new hamon. Then the re-tempered hamon starts with mizukage.

This blade was polished very well by the modern style. Of course the hadori (white pattern) was made as one continuing hamon pattern. So it was a little difficult to break the trick of step-tempering.
Anyhow, it is impossible to connect new hamon to the original hamon.

 
Fake signature (gimei), counterfeit
A signature put on the different blade. It was purposed to deceive collectors.
Do not be enticed by the signature. The quality of the blade is most important.
 
introduces an example of very bad inlay work on the tang.
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Once I have seen a very good blade with a full length at some Kantei game.
I was sure it was made in 12th century.
When the handle was taken off I was so surprised.
Because, the tang was originally unsigned and had an original shape, but it had a gold inlay that was made recently.
It was two letters of the name of "Yoshikane" and the signature of professor "K.H".
It meant that the professor "K.H" attributed the blade to "Yoshikane"(in Kobizen school).
 
This gold inlay was a very big flaw even if it was beautiful.
The originality of this tang was broken by this work.
Serious sword lovers never do such work because they respect blades.
I am sure the person who produced this inlay does not love swords.
He is only playing with them.
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Generally a gold inlay of a smith's name has to be done at the same time of shortening the blade, being sorry the signature disappear.
Sometimes, old Hon'nami put their attributed name with gold inlay on the shortened tang.
An attributed name has to be done with lacquer.
A red lacquer is on the original unsigned tang. A gold lacquer is on the shortened tang.
 
Un-original engraving (ato-bori)
If it accords with the blade, it is not so bad. We can not find any problem on it.
In old days, engravings were added on blades for prayer. On old blades, it is not easy to find if the engraving would be done originally or later. But recently it was occasionally done to mask flaws. Such a work that break blades is so bad.
An open layer is far better than a terrible dragon.
 
These two Sanskrit-like letters are so bad. The worth of the blade disappeared forever.
 
-Do not restore an original engraving-
Some engravings in old blades have been partially erased by much polishing. I wonder if you would like to restore it by some craftsman. But please never touch the original engravings. Engraving is not only a decoration put on the blade. It is a prayer of samurai old days. You should respect original engravings even though it is erasing.
-Examples-
Suken by Kuniyoshi: the centre line of suken has worn out.

Kurikara by Kagemasa: the dragon has worn away in some parts.

 
Broken cutting edge (ha-kobore)
A small nick on the cutting edge is not a big problem, to keep a good shape is more important.

 
Notches by battle (kirikomi)
It should be called a pride rather than a flaw.

This cutting mark still has the enemy's edge bitten off. It came from an old day's sword fight.
 

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