Question about hamon and blade's state

[Yumso]

Hello dear NMB members,

Today I wanted to ask about what each hamon state tells about the blade's healthiness. Below are the 4 states of hamon that I've drew.

From what I've read, it seems like #1 and #2's difference is only how the polisher polished the blade(something like "make-up" difference), so both are fine and in good condition. #3 and #4 are the ones that confuse me.

For #3 I'm assuming the "erasing" occurs because micro scratches make the blade blurry, showing time has quite passed after polishing so it may be good time to get new polish for the blade. I assume that's not a critical flaw. Or maybe that's how blade's tiredness shows?

For #4... where quite rough scratches(maybe because of cutting tests or amatur polishing attempts) seem to erase or disconnect hamon, I really have no clue about how I should evaluate the blade when I see them. Are these critical? Or would polishing fix them?

[eternal_newbie]

As far as the hamon is concerned, it's the nioiguchi that's most affected by tiredness. It can fade in places or be completely gone if the blade is tired enough (this looks like picture 4 in your diagram, but without the scratches - it's just that the hamon becomes weaker or vanishes in places). That said, it's also dependent on the school and the smith; some smiths have a subdued or hazy nioiguchi as a kantei point, while others are expected to have a nioiguchi so clear and bright you can practically see it from across the roo

 

The differences between 1, 2 and 3 can be the result of polishing, but they can also be the result of the makeup of steel and activities within the hamon (some will have an almost machine-made straightness and absolutely no variation in steel colour or activity; others will have all sorts of different steel, nie and nioi colours as the various steels interact and form activities).

[Yumso]

Rohan,

Thanks for the knowledge.
I have one more question: can nioiguchi also be restored by polishing? Or should the blade be reforged to make it?

[eternal_newbie]

10 hours ago, Yumso said:

can nioiguchi also be restored by polishing? Or should the blade be reforged to make it?

 

If it has been obscured by scratches or rust, a new polish will most likely be able to restore it. If it is gone due to fire damage, then yes, the blade must be re-hardened (saiha) to restore a nioiguchi. If it is gone due to tiredness then the blade is beyond recovery - too much material has been lost to even attempt re-hardening it.

 

You can see an example of this re-hardening process on the Usagiya website: http://www.ksky.ne.jp/~sumie99/sword6.html

[Tim Evans]

If there is a nioi-giri (a gap in the nioi-guchi) then it may be possible for a polisher to make a cosmetic repair so it is not as noticeable.