Sword flaws

[Ken-Hawaii]

I was very interested in a late-Kamakura/ early-Nambokucho katana that I found for sale, & the seller was kind enough to send me about two dozen high-resolution images. Looking closely, I spotted what I initially thought was a small amount of pitting about two inches from the machi, but was suspicious because it appeared the pitting was on both sides of the blade. I asked him to take a look with a magnifying glass, & he came back with the verdict that it was indeed a hagire, & took the blade off the market. Nice to have an honest seller!

 

But my question is this: if there's a hagire about 1/16-inch long in a blade with a substantial hamon, could it be polished out? Or is a hagire an intrinsic flaw in the steel that will continue to propagate even if the original crack is polished out & removed?

 

Ken

[b.hennick]

Hi Ken:

That is what machi okuri is for. You move the machi up and the hagiri disappears. I do not me an the habaki hides it but that it is removed in making the machi.

[cabowen]

Sometimes, as Barry has mentioned, you can get lucky with placement and remove it. It is possible, if the hamon is wide and the hagire shallow, sometimes it can be polished out, but that is pretty rare...

[Ken-Hawaii]

The blade isn't long enough to move the machi two inches, but the hamon is very healthy for a Koto sword, so a heavy polish is about the only thing I would consider if I bought it.

 

But my question is really what causes a hagire? Obviously, the smith made a mistake somewhere in the forging process, but is there an underlying flaw in the steel that would cause it to propagate after the original hagire is removed? I can figure out how most ware are formed, but a crack has me scratching my head. Any togishi out there who can give me a clue?

 

Ken

[cabowen]

Hagire usually form during the heat treatment, which is extremely stressful as the edge tries to expand while the back resists as the steel cools extremely rapidly. Run a glass under hot water then quickly quench it in cold water and you will get the idea..

 

Sometimes a blow against something very hard, a bend, or a twist can also crack the edge, which is quite hard and brittle and is nowhere near as ductile as the body of the blade.

 

It usually doesn't have a lot to do with the forging; it is more about the brittleness of the edge.

[Chonmage]

I'm not very happy with myself missing the hagire.

 

Edit: I had a hard time getting both sides to reflect light properly. There hagire is visible on both sides, yet hard to see on one side. I'm not sure if it is visible to you, but it only starts at the edge on one side. Or perhaps it is so thin that I couldn't even pick it up the end of it with the camera or magnifier.

 

 

 

 

Anyway, thank you for your time and input. I appreciate any chance to learn.

 

For those of you with dropbox (Set1 and 2): https://www.dropbox.com/sh/20dpawl3esv7 ... BJWta?dl=0

If that doesn't work then send me your email and I will invite you to it.

 

Photobucket (Set 2): http://s1241.photobucket.com/user/Chonm ... y/Kunihiro

 

The photos are raw, with overexposure and underexposure to bring out the most of the set.

 

 

 

Kind regards,

 

Anders Olsson

[Marius]

Anders,

 

loads of pics, thank you. On which one of these is the hagire visible? Do I understand you correctly, does it show only on one side of the cutting edge?

[Chonmage]

Hi Marius,

 

I realize I was unclear in describing the hagire.

It's visible on both sides. With the photo bucket link, it should be the first photos.