Pic of shinae?

[Marius]

Gents,

 

does anyone have pictures of shinae? I could find a few only on the Usagiya site...

 

Also, opinions on shinae from the metallurgical point of view would be very interesting. Oh, and I don't mean the shinae which appear as the result of bending/straightening the blade, but those which are related to the quality/pureness of the steel.

 

Thanks

[cabowen]

Shinae are wrinkles caused by bending. They aren't related to the quality/purity of the steel.

[Marius]

Chris,

 

thanks. What do you think of the distinction mukade shinae/shinae as outlined here:

http://www.ksky.ne.jp/~sumie99/flaws.html (scroll to "shinae")

[cabowen]

I have never seen such shinae attributed to simply "poor steel". I have difficulty understanding how forged steel can crack on its own across the grain. Interesting.

[Marius]

I am not saying that they are right I agree, steel will crack when under pressure. I have once owned a tanto, a thick yoroi doshi by Tosa Yoshimitsu, and it had these cracks in the mune. I really wonder what causes them... In this particular case, the tanto was too thick to bend (motogasane of 9 mm, nagasa of 22 cm).

[mdiddy]

I wonder if shinae (cracks not wrinkles) along the mune could come from issues during yakiire or adjustments to sori after yakiire. I inspected a well mounted unokubi-zukuri tanto by a Jo Saku Shinshinto smith once. The tanto had deep sori, however the unokubi-zukuri portion of the mune was strewn with cracks along the mune. I assumed it must have happened during yakiire or after if the smith tried to adjust the sori but I do not know for sure.

 

I might have saved some photos and if I can find them I will post them.

[ROKUJURO]

Gentlemen,

 

the upper two pictures of SHINAE on the KSKY website do not show a 'weak' or 'poor' steel. These kind of cracks are typical for a local overheating in the forging process or, as Chris points out correctly, in the hardening. I have seen this a number of times, and it always looks exactly the same.

 

In fact, these cracks across the structure of the steel represent a weak spot in the blade and might cause failure in use/battle.

[runagmc]

Gentlemen,

 

the upper two pictures of SHINAE on the KSKY website do not show a 'weak' or 'poor' steel. These kind of cracks are typical for a local overheating in the forging process or, as Chris points out correctly, in the hardening. I have seen this a number of times, and it always looks exactly the same.

 

In fact, these cracks across the structure of the steel represent a weak spot in the blade and might cause failure in use/battle.

Maybe that's what they mean by "weak" and "poor" steel... the actual material (steel) may not be weak or poor, but the forging has left it weak...

[ROKUJURO]

Adam,

 

thank you! That's what I wanted to express!

[John A Stuart]

撓え are faults caused by bending causing cracks or wrinkles. Look at the root 撓. Cracks caused by yakiire or improper forging would be hibi 罅, I believe. John

[leo]

If you are referring to shinae in the mune, I think they are rather produced by "straightening" than by "bending", because most blades have a sori.

 

I think in this case the expression is wrong because "bending" implies that somebody "bends" a blade downwards until shinae appear on the mune. I cannot imagine anybody doing this. It is rather a result of improper heat treatment.

 

This is part of a thread about shinae and hagire posted here before:

 

"Usually this happens when the blade straightens itself due to(unwanted) stress relief.

When a blade is tempered, it bends upward and a lot of structural stress is built up. This is usually relieved afterwards by a low- temperature heat treatment.

If this is not done accurately or not at all, there will remain unhealthy tension. Depending whether this is towards yakiba or towards mune, there will be hagire or shinae.

 

Unfortunately these not always appear immediately, because then the blade would be scrapped. These cracks usually show after centuries of use and repeated polishings, when the thickness is reduced and the structure thus weakened."

 

Best,