Dulled Edge

[mike yeon]

Question.

 

Does anybody know what the Japanese term for a blade that has had it's edge dulled on purpose during polish?

 

One of our senior Japanese advisors said it while commenting on a blade I brought to the NYC club meeting. It escapes my mind at the moment. The blade is in full polish but the edge is not razor sharp. I did ask him why this would be done and he replied "for storage". Would there be any other reason?

 

Curious to know.

 

mike

[Nobody]

Habiki (刃引)?

[Guest reinhard]

Just guessing: To avoid serious injuries, when practicing real man to man situations? As far as I know, Japanese even dropped wooden bokken for doing so, since they can inflict lethal cuts.

 

reinhard

[Aloof Pegasus]

Kashima Shin uses a leather covered fukuru shinai. Even regular shinai can splinter.

[mike yeon]

  Quote

Habiki (刃引)?

 

YES!!! Thank you once again Moriyama san. This felt like scratching a long standing itch...

 

As for the theories on why this would be done, I agree with the practitioner route. Perhaps done so that when you draw the blade while practicing kata, there's less of a chance you damage the mouth of the saya.

 

Thanks all.

 

mike

[Chris Colman]

Hi,

 

During our first visit to Japan last year, in Seki City we watched a demonstration of Iaido and tameshigiri.

At the end of the demonstration the sensei showed their katana to the audience, all were blunt as a thumb run along the edge proved.

The particular school, unfortunately I don't remember the style, always use a blunt sword, "a true swordsman does not need a sharp sword to cut", "the speed of the cut is critical".

regards

chris colman

[James]

I remember reading somewhere that Samurai would slash their swords in the sand/ground before battle to dull the edge. I believe the reason was that a sharp edge would bend when striking the enemy's armour whilst a dulled edge would not.

[Brian]

I can think of a lot of reasons that that wouldn't make sense, and almost none that it would :D

Let's call that source severely "suspect" unless proven otherwise shall we?

 

Brian

[Brian Pedersen]

Regarding the question about a dull edge..

 

I am not sure if you refer to the area from the ha-machi and a few cm up?

This is called ubu-ha and is always present on a gendaito.

The reason we polishers don't make this area sharp from the beginning,is that it allows for a number of polishes, before the ha-machi starts to get smaller..a thing that is very common on older swords.

 

If, on the other hand the whole edge is dull (and how dull is dull?), despite a new polish, i am afraid i would have to say that the polish, in my opinion is..shall we say less than satisfactory!?

 

Of all the swords, i have polished and handled over the years, all been sharp in varying degrees.

I for sure have never heard that you should dull the edge for storage...

 

Just my thought for what it is worth.

 

Regards

[mike yeon]

Hello Brian P.

 

It's not ubu-ha. As you mentioned, ubu-ha is located at just the first few CM starting at the hamachi. This blade is the same in sharpness up and down the length.

 

Going off topic for a moment, when did the practice of ubu-ha start? I've seen ubu-ha on blades from Gendai to Shinto (I once owned an Echizen Kunitsuna (early 1600s) wakizashi that was in outstanding condition with ubu-ha.)

 

Also, with ubu-ha the edge is flat. The sword in question the edge seems "rounded". As for sharpness, it looks pretty sharp. It's not dull like an iaito dull. I'd say that it would cut you just the same as something "razor" sharp. In fact I didn't really notice it until it was pointed out.

 

It's a signed and dated Koto sue-bizen shobu-zukuri katana. Not kazu-uchi-mono as the quality is outstanding and it is signed "Bizen no Kuni Ju Osafune Sukesada Saku". It's dated 9th year of Eiroku (1567).

 

The polish is older and was done in Japan. I think it's actually very nice, and the blade is very healthy. (attached a picture of the hada).

 

Let me know what you think.

 

mike

[Brian Pedersen]

HI Mike

 

It does indeed look like a very good blade!..though i would much prefer to have a hands on experience

 

If it is sharp, sharpish, then it could be that there is an excessive amount of niku right at the ha-saki, making it look roundish..but without a closer look, i am afraid that i can't really tell you.

 

As for the origin of ubu-ha..i would imagine that ubu-ha was present in koto too...but due to polishing it has been lost over time.

As you said yourself, in shinto and shin-shinto, you can still see ubu-ha on some well preserved swords.

[paulb]

Brian,

Not suggesting it is the case with this blade but am I right in thinking that if a smith had to re-temper a blade they would take the edge back (dull it) to a thickness that could withstand quenching? If so is it possible that some of the dull edged blades seen are a result of retempering and where the blade has not been brought back to full sharpness?

[mike yeon]

  Quote

Brian,

Not suggesting it is the case with this blade but am I right in thinking that if a smith had to re-temper a blade they would take the edge back (dull it) to a thickness that could withstand quenching? If so is it possible that some of the dull edged blades seen are a result of retempering and where the blade has not been brought back to full sharpness?

 

After a blade is retempered, it still gets polished. My guess is that the togishi gives it an edge as normal. Retempered blades were meant to be used again.

 

And just for the record the sukesada has not been retempered. :lol:

 

mike

[johnb]

Maybe some chips were remove from the cutting edge this would mean that whatever material was removed to get rid of the chip and to avoid an ugly dip material would have to be taken from the full length of the blade. Once it was reshaped, and it could be as little as a millimeter, perhaps the polisher decided to leave the blade blunt rather than cut away to much meat. After all, we're more about looking at em rather than chopping people up with them. With regard to ubu-ha I personally believe that all swords were originally this way to reduce damage to the habaki when removing and replacing for cleaning. Obviously over the years on older swords, it enevivtably gets polished away. All guess work by the way!!