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Is it easy to spot a saiha (retempered blade) ?


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Hello, is it possible to spot a re-tempered koto blade easily, before polishing? Or is it just a polishing that can reveal the mizukage?

 

I bought my first sword via Ebay from a member of this group some time ago. Even if the seller is knowledgeable and described it "fully", he never ever said it was a re-tempered blade. It is only after polishing (that cost me a leg and an arm) that I was revealed by the polisher, the presence of the mizukage.

 

Laurent

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Hello:

I am sure there will be many replies to the question, but here are a few tips that might be useful.

Mizukage, the starting of what looks like looks like straight line utsuri, but fads out quickly, from the ha-machi at about a 45 degree angle on an ubu blade, is the classic sign. However Horikawa blades in general may and those of his top student, Dewa Daijo Kunimichi, will usually, have that trait. Thus it is not always a flaw. Also it is common to see what looks like the start of mizukage on old Bizen blades that do have utsuri, however in that case the utsuri will continue normally up the blade and what is seen is not saiba. Utsuri itself starts somewhere.

General things to watch out for are temperlines that are unnaturally wide on old and much polished blades, discontinuities in the nioiguchi or spots that can be functions of lost clay in the retemper process. Retempered blades, if they are suriage, will have the hamon coming from the ha-machi, or the nakago will be unsually free from rust from it having flaked off during the process, or it will be too blue in color. The blade will tend to look dry and too bright. Look for hamon in the boshi for if in good shape elsewhere it should also look clear in the boshi which is a challenging area for the saiba process. Watch out for a blade with too much sori for its age or function. It may just be my imagination but retempered blades seem rather heavy, tip heavy, but so do shinshinto, so that could be misleading. Also watch for saiba in selective places, though that is even harder to disguise, for example in replacing an entire boshi where the kissaki may have broken off.

Many Japanese blades have been damaged by fire and I suspect there are more retempered blades out there than we imagine, and like all things having to do with swords there are both good and poor craftsmen, and some saiba are very well done. I know of one case where the NBTHK knowingly papered a koto saiba of an excellent smith, and I am sure there are more.

While most collectors wouldn't knowingly want a saiba blade, for others it might be seen differently if the blade is still in keeping with the style and character of the original and its condition taken into consideration on the price.

These are only a few things to consider.

Arnold F.

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As so well explained by Arnold, mizukage on its own is not a clear indicator. In fact, if you read "Facts and Fundamentals of Japanese Swords" there is a section that says it is not an indication at all, and that many swords have mizukage by design.

It needs to be combined with the other indicators mentioned.

 

Brian

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The other issue that Laurent's post raises is the peril of buying an out of polish blade from Ebay. It would be lovely if every out of polish blade turned out to be wonderful once the polisher works on it but that is a risk that we take when we buy the blade, is it not? The risk is great enough when we have the blade in hand, at least we have the opportunity to study it closely whereas any internet purchase does put one at the mercy of digital photographs at the very best. While some flaws may be obvious, even in an out of polish blade, others may only reveal themselves once the polisher removes metal.

 

Of course some of the treasure hunter lives in all of us and the temptation to take a gamble is strong. Usually the best stories about great blades bought unpolished and restored to glory tend to come from experienced collectors. I have a painful story about a seemingly undistinguished armour that had passed through the public marketplace for some time and been dismissed by many including myself. An experienced collector quietly snapped it up because he recognised it for what it was. Fortune it seems, favours those who study.

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A blade can be re tempered & certified by Shinsa panel - however it will be notated on the certificate as such .

Re tempered blades seem to be an avoidance/deterent to most collectors

What should be considered is the fact that some blades are solely retempered due to the fact - it is the only chance to preserve the blade

Therefore in the case of an old blade by a famous maker - does one consider it worthless due to the fact it's been retempered ?

Beauty & value is in the eye of the beholder

At the end of the day - anything 2nd hand is only worth what someone is willing to pay !

Cheers , AlanK

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  • 2 weeks later...

Hello:

I would be interested in reading a further discussion by Chris on "hardening" and "tempering" as I realize these terms are sometimes used interchangeably to say nothing of misused. I have thought that if "hardening" is used with care it is used to describe the process of heating a blade with its clay coating having been applied and partially wiped off to determine the hamon proper, and then being plunged into a water trough at just the correct temperature. A second quenching following a reheating is then employed to relieve stresses in the metal induced by the initial yakiire process. When saiba is involved that can be for a blade that has lost all of its hamon due to say fire, or it can be done selectively to repair a clay loss somewhere during yakiire or perhaps an entirely lost boshi through breakage. Why would a retempering, given the above usage, be done at all unless part of an entire re-do of a blade sans hamon?

Arnold F.

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In metallurgy, hardening and tempering have specific, and different meanings.

 

Hardening occurs when the blade is brought up to a certain temperature (called the critical temperature) and cooled at a certain rate to produce martensite (the yakiba). It is very hard, brittle, and as Arnold has mentioned, contains considerable residual stress.

 

Tempering is the process of relieving some of this stress by heating the blade slightly and allowing it to cool. This relieves a bit of the stress and thus some of the brittleness and makes the blade tougher.

 

Tempering can be done by heating the blade in the forge, though this is very tricky and dangerous as too high a temperature and/or an uneven temperature can remove too much hardness or make the blade uneven in its hardness. As a result, most tempering is done in a temperature controlled furnace or oil bath (which is what was used at the Yasukuni forge). It is thought that not all smiths temper their blades, though the benefits are real and significant.

 

There is no reason to retemper a blade unless the tempering temperature was too low for some reason the first time. Too high a tempering temp can cause too much of a reduction in hardness and there is no way to get it back without rehardening.

 

Rehardening (saiha) can not be done on only the boshi without a nioi-gire and usually mizukage. Removing muneyaki or unwanted spots of martensite due to clay falling off can be done by local heating, if done with care and skill, in some cases.

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I have a terminology question that I can't remember ever hearing addressed before. It's probably kind of nit-picking, but it would be interesting to know how the terms saiha and yakinaoshi are used by kaji... and if they are used interchangeably, or not.

 

To me, it seems it could make sense to use the term saiha (translated as 'redone edge') only when the entire edge is rehardened, leaving the term yakinaoshi (naoshi meaning to correct or repair) for partial corrections or repairs to the yakiba. Anyone have any insight on how these terms are used by the craftsman themselves, or any thoughts otherwise?

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