Japanese black persimmon, can I save it??

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Wabisabi-Ken

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Hey guys, sooooo I'm keen to get into making my own knife handles and saya.

I got a hold of some beautiful black persimmon wood and want to make a saya for a gyuto of mine. The problem is I have only very thin pieces to work with and I can see some cracks along the grain of the wood.

I was wondering if I could maybe use epoxy to try and fill/strengthen the wood? Or is there any other kind of way to make it useable and safer to work with? With how thin it is a don't have any margin for error! Hell I might be dreaming of being able to pull this off at all with the thickness of wood I have (6mm). I have looked into stabilising the wood but don't think it will help with the split parts?

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Hopefully you can see it there but the split is basically right through and goes up a fair bit, I'd rather be able to use that part of wood as it looks awesome. Help!!
 
Stabilize it. As far as the thinness, will probably have to use a 3 piece construction.
Will the stabilising actually stop that crack getting worse? Ill have to look into stabilising a bit more since right now I can't justify a full vacuum setup. I think some kind of epoxy was was another way to stabilise wood? I guess I have to do my research!
 
I’d do a 3 piece like m1k3 said. And use the wood dust from the persimmon and some glue mixed together to fill the crack. I think you’ll be paying fairly substantial money to send it out to be stabilized
 
That split in the end is called "checking", in case a wood forum has any advice.

My take is to work around or with those checks. If you can make a three piece saya, you'll have best luck. You can layout the saya with the point toward the end, and avoid the check.

You can fill the check with epoxy, that's a done thing for live edge construction and will provide a little strength. Wood glue and sawdust will look ok, and provide no strength. Wood glue is 50% water, and that water evaporating is what sets the glue. Therefore it is not good at filing voids.

Maybe take the wabisabi approach, lean into the check, either by working around it or highlighting it in a complimentary color.

Good stuff from about 6:23 - 7:30


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Very beautiful wood you've got though!

The check's either a product of the wood not being dimensionally stable--either it was cut from a block too soon or it responded to big swings in humidity/aridity--or it's actually a crack from being bent and then splitting along the grain. If the latter, it may keep moving further up the grain. If the former, it may check elsewhere. Or, maybe nothing more happens. Stabilizing should help, but not a lot because the pieces are so thin. Stabilizing may alter the colors a bit. Epoxy will lock that check.crack down. But use an eopxy with some flex. Sometimes locking down one crack just helps the wood find a weak spot along the grain somewhere else. One way to find out :)
 
@cotedupy might have advice, hes a god with epoxy


Haha, cheers! I do indeed do this kind of thing all the time :).

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So first thing to say is - while stabilizing the wood alone won't fill those gaps, you can stabilize it and then fill them. That's going to be your absolute best option for making it safer to work without breaking.

If the wood is dense enough that it doesn't necessarily need stabilizing, then yes - filling the cracks or gaps with epoxy will work well. A clear 2-part epoxy fill will be basically invisible on cracks in the darker areas, but would look dark if there are any cracks in the white parts.

To do the fill - take a thin blade or something pointy and clean the crack up a bit. You're not trying to carve into the wood as such, just making the gap more uniform and easier for the epoxy to get in. Also - work with epoxy that is slightly warm (bit above room temp), this makes it a lot more liquid and will get into the gaps, as well as meaning air bubbles will get out of it better, and make the finish clear rather than cloudy. NB warm epoxy does set a little more quickly than cold, so you need to work a bit faster.

You could try doing this with CA glue / superglue instead, but I'd go with epoxy for the reason that @captaincaed mentioned above. CA sets because of evaporation or contact with air, which means it can't really be used to fill significant spaces. Epoxy sets because of a reaction between the two parts, so will do so all the way through. If you used CA glue you would need to do a little bit at a time, let it set, pour another few drops in, let it set, &c. &c.

Hope that helps OP!
 
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Really beautiful bits of wood you have there! Can't wait to see what they look like sanded and finished!

Those checks arent that serious. I have done quite a few sayas with burl wood thin stock that has, at times, been worse than that. I have tried both CA mixed with saw dust and epoxy mixed with saw dust. Depending on how deep the split is you could get away with either. The epoxy will lend more structural support. CA sands shiny, Epoxy sands gummy. That will be the biggest challenge, trying to blend in the color and grain. As other responses have urged, a 3 piece design will lend more strength to the check. I would put the more serious/visible side towards the outside. As you sand, you will reach down to the less visible part. 6mm is plenty thick for a saya. That is what I typically use to carve out a 2 piece, so with a 3 piece, you will have a fair amount of stock removal to make it more elegantly thin
 
Haha, cheers! I do indeed do this kind of thing all the time :).

---

So first thing to say is - while stabilizing the wood alone won't fill those gaps, you can stabilize it and then fill them. That's going to be your absolute best option for making it safer to work without breaking.

If the wood is dense enough that it doesn't necessarily need stabilizing, then yes - filling the cracks or gaps with epoxy will work well. A clear 2-part epoxy fill will be basically invisible on cracks in the darker areas, but would look dark if there are any cracks in the white parts.

To do the fill - take a thin blade or something pointy and clean the crack up a bit. You're not trying to carve into the wood as such, just making the gap more uniform and easier for the epoxy to get in. Also - work with epoxy that is slightly warm (bit above room temp), this makes it a lot more liquid and will get into the gaps, as well as meaning air bubbles will get out of it better, and make the finish clear rather than cloudy. NB warm epoxy does set a little more quickly than cold, so you need to work a bit faster.

You could try doing this with CA glue / superglue instead, but I'd go with epoxy for the reason that @captaincaed mentioned above. CA sets because of evaporation or contact with air, which means it can't really be used to fill significant spaces. Epoxy sets because of a reaction between the two parts, so will do so all the way through. If you used CA glue you would need to do a little bit at a time, let it set, pour another few drops in, let it set, &c. &c.

Hope that helps OP!

how about your colorized epoxy
 
What Cotedupy said.... I have done just a ton of stabilizing, but mostly spalted woods, and that is a new ball game. In any event, look up
Cactus Juice Stabilizing Resin, Chambers, and Accessories and go to the stabilizing web site of facebook Wood Stabilizing | Facebook
And learn about stabilizing before leaping off of the really tall cliff. If you do not want to go through the efforts required, and it is just a lot
for a one of, you could consider having Terry Dunn, who posts a lot on the facebook stabilizing group do the work. He is remarkably good,
and has a lot of good advice. Войдите на Facebook
By the way, persimmon, and the various versions thereof, like Texas persimmon are all in the ebony family. See the genus name Diospyros - Wikipedia . My brother's ranch has just acres of Texas persimmon, and large specimens have a nice smattering of
black throughout, but the shrinking/checking while drying, is a really difficult process to deal with to come up with a piece even large enough for a
knife handle . I have lots of experience with this as the wood is beautiful till the checking gets through.
 
In the old days I would fill wood gun stocks with clear epoxy. Clear epoxy has a golden color that blends with wood.

With that board you could rip it up through the crack and then glue it together if you need a board that wide otherwise just rip it and use it as a smaller board. You will need a table saw to rip and probably a ripping blade. Don't try to use a crosscut blade. A combo blade will probably work but I prefer a crosscut blade and ripping blade. They are easy to change on my old Delta unisaw.
 
Thanks for all the replies guys! for some reason I wasnt getting the little notification sign when I was on the forum so didnt know I was getting responses.
Anyway, good food for thought.. before seeing these replies I just tried using CA glue since I had some lying around and figured the cracks are so tiny that a bit of CA should probably do the trick. I would like to have a go with epoxy but its just damn expensive and with this being my first outing I want to try and do it on the cheap at first. Also I am living and doing everything in a tiny Japanese apartment bedroom haha. So, for now cactus juice and epoxy are not on my list unless absolutely necessary.

The message about persimmon being part of the ebony family makes sense, the wood itself does seem quite dense and I dont think it will really benefit much from stabilizing... I could be totally wrong though, just a hunch.
I will do some research into saya making, Ideally 2 piece as it seems like I could keep it nice and thin, I really dont like the look of bulky ones at all. I only really have hand tools, think a regular woodworking chisel would do the trick? Or do I need to find a curved one? I guess theres only one way to find out and jump right in.. I think making a saya is probably the easiest part of it all, I have gone wild and aquired some awesome wood to work with for handles also, the scariest part of that exercise will be trying to drill tang holes without a drill press haha oh man... anyone done it by hand before? I guess I could squeeze a drill press into my room :D
 
That split in the end is called "checking", in case a wood forum has any advice.

My take is to work around or with those checks. If you can make a three piece saya, you'll have best luck. You can layout the saya with the point toward the end, and avoid the check.

You can fill the check with epoxy, that's a done thing for live edge construction and will provide a little strength. Wood glue and sawdust will look ok, and provide no strength. Wood glue is 50% water, and that water evaporating is what sets the glue. Therefore it is not good at filing voids.

Maybe take the wabisabi approach, lean into the check, either by working around it or highlighting it in a complimentary color.

Good stuff from about 6:23 - 7:30


View attachment 187440

Yeah epoxy was my thought. Or ca glue.
 
A saya nomi, or chisel for making scabbards or sayas would be ideal... I forged one from laminated 1018 and 52100 several years ago, and the main feature that is useful is the curved shank... The use is pretty straight forward, as with the curve it is pretty easy to dig out the wood to be removed.. This can be done
with a regular straight shank chisel, but much more difficult to control .. This is more of a very sharp , push the chisel , type movement than a mallet assisted
cutting. The saya nomi should be pretty easy to find in Japan.
 
you can use thin CA glue with a colored filler, if needed speeding up setting using some bicarb. I did the bakelite handle of my Espresso Lever that way (using charcoal as filler). You can hardly see the repair.
 
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