Shirasaya - repair

[remzy]

Greetings,

Looking at the other thread about shirasaya, a question arose in my mind, i have a tanto in shirasaya that is somewhat spliting apart, so i was wondering if it would be a good or a bad idea to try and glue it back together with rice paste glue. is there a special technic required to ensure quality? I didnt see much on that matter in books ive red.

 

thanks,

Remy

[Darcy]

I've done it. My results were mixed, I just tried a couple of times. I think it probably takes some refinement of the technique.

[Ken-Hawaii]

Same here, Rémy. I could live with the results, but my shirasaya certainly didn't look exactly like all my others. Probably a function of how much water gets mixed in, the drying rate, humidity, & a bunch of other factors.

 

But at least it was inexpensive...!

[remzy]

Hmmm okay, so their has to have a special technic to apply the glue then i presume...

 

thanks for your answers guys.

Remy

[Brian]

From a few websites:

Once the woodcarver is certain that the interior of the saya has been properly carved, he will begin preparing the glue that will be used to hold the two halves together. The glue used for this is made from one or two-day old rice. Rice glue is used because it's strong, but not so strong as to prevent the saya from being separated again for occasional cleaning of its interior. Using a spatula, the woodcarver mixes a small amount of the rice with a few drops of water. This forms a thick, sticky paste which is applied to the perimeter of the two saya halves. The two halves are then tied together very tightly and allowed to dry overnight.

Use day old rice that has been in the 'fridge overnight and use a lot of water when you cook the rice. Use big fat wet sloppy soft rice. Put it in a blender and whip the snot out of it and add a little bit of water at a time til it is the consistancy you like. Mashing it with a fork or a paddle is a PITA and it never gets all the little hard bits out.

 

I remember reading somewhere that when a shirasaya starts to split, just dabbing slightly warm water on the splits with your fingertip and letting it soak for a while will soften the rice glue, and you can then clamp it again and it will stick. Can't remember where I read it though, so maybe I was mistaken.

 

Brian

[remzy]

Thats a very good idea Brian, i will try that if it split more, thanks!

[Ed Harbulak]

For centuries, violins and other similar Western stringed insturments have been put together using hot hide glue. The top of a violin is fastened with diluted hot hide glue so that the top can be easily removed from time to time for repairs or other needs. I have used diluted commercial liquid hide glue to fasten the two halves of a newly made shirasaya together. It holds well enough to keep everything together, yet with a little pressure applied to the inside the shirasaya will split open for cleaning. While applying a bit of water to an opened rice glue joint on a shira saya should work, you can also try some diluted liquid hide glue. Work the glue, or just water into the split with a thin bladed spatula and tie firmly till dry.

Ed

[Stephen]

of rice is the key, short grain like the kind you use in resotto, think its called Arborio, more starch i belive.

[johnb]

I spent some years working part time as a quitar maker and repairer, a lot of the things I have learnt can be applied to our particular past time.

The main issue is, is the shirasaya splitting into it's two halves or is it developing a crack?

If it's splitting into it's two halves then the idea of warm water worked into the opening to soften the rice glue is a really good idea, assuming that you can squeeze the opening together by hand. A good way to clamp the joint while it dries is to bind that saya with electrical tape as the elasticity of the tape will exert the required pressure. The trick here is to buy good quality tape and to use it upside down. In other words sticky side up. This means no residue from the adhesive is left on the shirasaya.

If the rice glue is beyond redemption then a kids PVA craft glue is a good subsitute. Craft glue is good as it is nothing like as strong as the handyman/carpentery stuff and it will still soften with water should you need to split the saya at a later date. If the opening is small then working some warm water into the opening prior to rubbing the glue in with your finger works really well.

On the other hand. for permanent repairs you can't go past super glue. The great thing is that if you can squeeze the crack shut you only need to hold it closed for a couple of minutes while the glue goes off...My policy with glue in all cases is... less is more. Don't over do it coz a little glue goes a long way. Hope this helps.

Oh, for my gluing credentials I have attached images of a vintage guitar that I have just removed, re-set and replaced the neck and finger board on. (The white line on the heel is a reflection not a crack).

[Grey Doffin]

Rice glue is best because it is reversible, it doesn't discolor the saya, it contains no chemicals that might discolor or corrode the blade, and it won't scratch the blade if some hardens inside the saya. I use Kokuho, a short grain white, which I get at Oriental groceries. If you google 'rice glue' you'll find directions to make the stuff at the 1st hit.

For clamping I use either of 2 methods. I tear an old sheet into long strips and wrap them tightly around the saya. I also use the paper and masking tape bands that I mentioned on another thread. Wrap a strip of white paper, a bit wider than masking tape, 1 1/2 times around the saya a few inches below where you want the band to end up. Wrap the paper tightly in masking tape. Slide the paper/tape band up the saya till it's tight. Prepare enough of these to clamp all loose areas before you apply glue.

Apply a tiny amount of glue, apply the clamps, and let it sit a few hours or more. I always let the saya dry for a day or so before I place the blade inside. Often, the 1st time I replace the blade the koiguchi (saya opening) is too tight. This could be due to temporary swelling of the wood from the moisture in the glue. If you wait a day or 2 the problem usually takes care of itself.

This will work if done properly. There is no reason to use super glue or any other chemical based wood glue.

Grey

[Ken-Hawaii]

I tried Kokuho rice, but ended up using Mochiko. There's almost nothing as glutinous - several hundred million Japanese use it for making mochi, which is about as chewy a food as you can get!

[remzy]

I remember reading somewhere that when a shirasaya starts to split, just dabbing slightly warm water on the splits with your fingertip and letting it soak for a while will soften the rice glue, and you can then clamp it again and it will stick. Can't remember where I read it though, so maybe I was mistaken.

 

Brian

 

I did exactly this today when i got back from work, warmed some water in the boiler, let it cool off a bit, dip my fingers in it and soaked the crack with about 10~ drops, taped it tightly with inverted electric tape (glued side up), let it rest for 3 ~ 4 hours and untied it.

Superb result, its perfect, thanks for the pro tip!