Naginata blade stuck in shirasaya

[MJS]

Hi all,

 

Today I tried to remove a naginata blade from its tsuka for maintenance, but it is quite stuck. I am very reluctant to use any force. The blade is sharp on both sides (see the image, is this called otoshi zukuri? What kind?).

We've had an extended dry period here in The Netherlands, with a bit of rain only the last few days. Is it possible that the dryness is causing this problem? If so, what is the safest way to add enough humidity so that the blade can be removed again?

 

Thanks,

 

Mark

 

[16k]

Yes, same thing for me in France. The very first time it happens. If there isn’t any emergency at stake, I would just wait. It’s what I’m doing. 
 

Otherwise, wrap some heavy cloth around the blade to hold it and use a wooden or rubber hammer gently on both sides of the tsuka near the Habaki. It should come off without damage.

[16k]

Another thing that comes to mind. Don’t knowing it is the case here (it is on one of mine) but if the saya has the same issue and feels to tight going to the top of the Habaki, don’t push it all the way. Push it just to the point where it feels secure and stop or you risk splitting the saya.

[Dave R]

Shirasaya are designed to split if needed. They are stuck with rice glue only, and my experience has been that overnight immersion in water will soften the glue enough to split the shirasaya.

[Ken-Hawaii]

Dave, he's new enough that we should specifiy that the shirasaya should not be placed in water, with the blade still inside.

[Grey Doffin]

I don't think it is a good idea to place shira-saya in water even if the blade isn't inside; this isn't the proper method for splitting the saya or tsuka.  As for the original question, place the sword in a more humid environment (the bathroom and take plenty of long, hot showers, for example), wait a week or so for the wood to take on moisture, and then use the proper tool (hammer & block) to remove the tsuka.

Grey

[Oshy]

Any of you ever make minor adjustments to the saya with a file or something to help the habaki better fit all the way?

[Ted Tenold]

I agree with Grey, but I'd go so far as to say submerging is a very bad idea for many reasons.  Like everything else, there is a process, and that process is also dependant in the glue that was used being ammenable to rehydrating and releasing.  

 

Living in a very dry environment myself, occasionally I encounter a blade that is stuck fast in the shirasaya.  The first thing I try is the same method as is normal for removing the tsuka from the sword, but holding the sayajiri end in hand instead of the tsuka.  Sometimes that will free it enough to remove it from the saya. Beyond that with a naginata you should have enough proud edge at the koiguchi to use an atekizuchi (hammer and striker tool for removing stuck tsuka).  Lay the Naginata flat in on top of a bed or padded counter and use the atekizuchi to dislodge the saya away from the blade.

[Ted Tenold]

Any of you ever make minor adjustments to the saya with a file or something to help the habaki better fit all the way?

 

Mike, yes, but you have to be careful to determine if the habaki is really the culprit first.  Sometimes the interior of the saya at the tip is binding and it may appear the habaki is jamming when it's not.  To find out mark the point where the daijiri of the habaki (the end of the habaki that would contact the seppa) on the nakago with light pencil mark, remove the habaki and slowly put the sword back in the saya.  If it bottoms out prior to the mark flushing with the koiguchi of the saya, then the habaki may only be part or not at all the problem, and altering the habaki's contact with the koiguchi won't resolve the real issue. 

[MJS]

Beyond that with a naginata you should have enough proud edge at the koiguchi to use an atekizuchi (hammer and striker tool for removing stuck tsuka).  Lay the Naginata flat in on top of a bed or padded counter and use the atekizuchi to dislodge the saya away from the blade.

 

 

Thanks Ted. This afternoon I saw the use of an atekizuchi in a video by Moses Becerra. He uses it while holding the tsuka in a vertical position, but putting the naginata on a bed is a great idea!

Now I'm off to find myself a suitable wooden hammer.

 

[MJS]

Thanks everyone!

I had not expected so many replies in such a short time. There are several good ideas (though I'll skip the aquarium for now), so hopefully I'll be more successful tomorrow.

[Alex A]

Ive had a few blades stuck in shirasaya. With the tsuka stuck, I just put a towel around the blade and gently tap backwards on the bottom of an heavy square table leg, never fails.

 

Obviously, gentle and handle carefully.

[vajo]

Mark when you buy a sword and it fit very tight you should wait some weeks. The wood need time to shrink. If it fits very thight the wood has some moisture. 

 

Store it on a dry place without any high humidity. 

 

Dryness is never a reason for a thight fit. Wet wood swell, dry wood shrink. And when it shrinks it doesnt get tight. 

[Ted Tenold]

Mark when you buy a sword and it fit very tight you should wait some weeks. The wood need time to shrink. If it fits very thight the wood has some moisture. 

 

Store it on a dry place without any high humidity. 

 

Dryness is never a reason for a thight fit. Wet wood swell, dry wood shrink. And when it shrinks it doesnt get tight. 

 

 

Nope, it's counter-intuitive, but it's the opposite.  I live in a dryer environment than the swords that come to me are from (Japan).  Relative humidity is very low here and they shrink and sieze up.  I take them to the humidity of Japan and they expand and loosen up.  

 

The difference is that a shirasaya has a hollow center with two walls in cross-section to absorb or lose moisture rather than a solid mass like a plank or board.  The shrinkage and expansion occurs effectually from the hollow center out when expanding (absorbing), and to the hollow center when drying (shrinking).  It's an effect of mass expanding out or shrinking in.  This is also evidenced in old tsuka which have dried out and are very tight, and/or have cracked along the corners of where the nakago sits.  

[Oshy]

As I track humidity levels I notice the fitment of habaki to saya becomes tighter the higher the humidity becomes. In the winter when humidity is very low, they all pretty much fit perfectly.

[doomsdaymachine]

As I track humidity levels I notice the fitment of habaki to saya becomes tighter the higher the humidity becomes. In the winter when humidity is very low, they all pretty much fit perfectly.

Lacquered saya or shirasaya? Lacquered saya have nowhere to expand but inward. Un-lacquered wood expands in all directions, meaning it gets taller and wider proportionately to inward expansion, changing the shape of the hole in the wood.

[nagamaki - Franco]

In regards to fit, much will depend upon the time of year and conditions of when the saya was made. Here in the NE USA, what I've experienced is that shirasaya made in this region will fit just fine throughout the year when made in the summer. However, if the shirasaya was made during the winter months, it will fit on the looser side come summer. For shirasaya made on the west coast or Japan during the summer months, come winter here in the NE the shirasaya becomes too tight. No matter what the case may be it means paying close attention, which you should be doing anyway. In recent years the change in weather conditions transitioning from fall to winter have become so sudden, even drastic, 60F one day, 32F the next, that if the sword is fully seated when that happens, it could mean the sword is locked down (safe and secure) until the following Spring. 

[Oshy]

All my blades are kept in shirasaya. I'm located in Minnesota, US.

[jeremy]

Here in Australia in the summer humid wet months, the tsuka on all my user swords start having gata gata, rattling inside the core agaisnt the nakago where I need to use shims to tighten the fit. In the cold non humid months where its really dry , everything tightens up including the koiguchi around the habaki as well as the nakago inside the tsuka core. And I've noticed its been like this ever since I started getting into swords back in 2003

[PNSSHOGUN]

Here there are particularly radical changes during winter and summer, combined with relative dry air and higher altitude there are some swords one simply doesn't attempt to remove the Tsuka from....

[Dave R]

 When you think about it, this does explain the rather radical storage strategy in Japan! Blade into the shirasaya, shirasaya into a katana-bukuro, katana -bukuro into a katana-bako! I have also read (here?) of a Japanese collector who would not open the box to show something off, because it was the wrong season/weather!