Jiita wood slab questions/opinions

[JoeWilson]

Hey all, I’m better at woodworking than bonsai and have some interesting lumps of wood (stumps, burls, etc) that might make good jiitas. I’m curious to hear some opinions and general info:

What sizes are typical/most useful?

How thick do you typically like the slabs to be? I saw someone in another thread say the thinner the better, but as a woodworker, this pains me a bit. Thin slabs tend to warp into potato chips, so generally the thickness of a slab would be proportional to its size.

How do we feel about cracks, rot, bug holes, etc? Defects to be avoided? Fill/stabilize with epoxy? Or leave them natural as elements of character?

What about bookmatched slabs? That is to say, two cookies from a half-log, sliced thinly, with one flipped over and then glued together at the center to create a mirrored pattern. I have a Russian olive stump that was too big to get on the bandsaw without trimming off more material than I wanted to, so I split it. Ignore the rough chainsaw marks; I was using this as a log cutting stand for a couple of years after I dug it out.

 

[rockm]

Thinner is better. Finding jiita over 12” long and the same deep is challenging and expensive for the reasons you cite. However those larger slabs are the most useful with bonsai display.

Thicker small slabs are hard to use in display because they look clunky and overshadow or even over power what is displayed on them.

Burl wood slabs are available on eBay if you look around. Those are sometimes iin the ball park but tend to be too thick or small.

 

[Jrmcmich]

Pretty cool stuff there. Wonder if you could add a pocket on bottom, with steel to keep from warping? I know Kitchens do this sometimes with granite slabs on an overhang more for strength but might be something

 

[JoeWilson]

Thinner is better. Finding jiita over 12” long and the same deep is challenging and expensive for the reasons you cite. However those larger slabs are the most useful with bonsai display.

Thicker small slabs are hard to use in display because they look clunky and overshadow or even over power what is displayed on them.

Burl wood slabs are available on eBay if you look around. Those are sometimes iin the ball park but tend to be too thick or small.

Thanks, I’ve been looking at sizes online, and it seems like they’re often 1/4-3/8” or so. But I found a couple of bigger ones that were closer to 1 1/4”, so I guess it varies a bit depending on size. Getting as thin as possible for the smaller sizes makes sense, wouldn’t want to overshadow the pot/tree. I'll do some test cuts on the Russian olive stump and see how much stress it has (usually if it's gonna warp a lot, it will pop right up after a day or two).

I have some really cool boxelder burl from a tree we took down when we bought the house, but most of it is milled up into rectangles of some size. So there would only be a live edge on one side. I could do straight edges on all 4 sides, circles, etc too. I see some of these online, but I’m not sure how popular dimensional or regular shapes are?

Here’s a funky slab from the stump of that boxelder. I have more blocks from this tree, a good deal of it is pretty clean (limited cracking and no rot) with some nice curl and burl figure, and the occasional red streak.

 

[JoeWilson]

Pretty cool stuff there. Wonder if you could add a pocket on bottom, with steel to keep from warping? I know Kitchens do this sometimes with granite slabs on an overhang more for strength but might be something

Yeah, I was wondering if that was common. It wouldn't be too difficult to route out a channel and epoxy in some steel. I'm not sure how much it would help, but it might make sense for getting super thin slabs.

 

[Jrmcmich]

Yeah, I was wondering if that was common. It wouldn't be too difficult to route out a channel and epoxy in some steel. I'm not sure how much it would help, but it might make sense for getting super thin slabs.

Yeah hard to know how it would do. I do Wood working myself but mostly kitchen cabinets and the like. Have done some tables and benches too but not anything with large slab but your right about wood moving and warping

 

[JoeWilson]

Yeah hard to know how it would do. I do Wood working myself but mostly kitchen cabinets and the like. Have done some tables and benches too but not anything with large slab but your right about wood moving and warping

Yeah, wood movement is the bane of my existence. I do a mix of stuff, some mid-century style furniture (shelves, coffee tables, that sort of thing) and some smaller decorative stuff, boxes, bowls, knife handles, etc.

I think I have a few more boards from this tree, lovely crotch walnut. This stuff has so much stress in it, though, when cut thin, it really wants to turn into a spring. I love burl and figured wood, but it doesn't always love me back. The light wood is the boxelder burl I mentioned earlier.

 

[Michael P]

Jita usually have continuous live edge all the way around but I have seen some cool stands with live edge on only the front.

 

[JoeWilson]

Jita usually have continuous live edge all the way around but I have seen some cool stands with live edge on only the front.

Yeah I saw a few nice ones that just had one live edge. I think I've got some good material to try something like that. Here are some weird contenders.

 

[JoeWilson]

And looming at the bottom of the wood rack, I've got these guys. I think I could do something like 24x24" slabs with these. Lots of chainsaw work required here, though, and I'm not sure how much figure they have. Might be better off trying to get a clean cut of the burl cap...

 

[leatherback]

Under half an inch else it is just too thick. Smaller sizes typically are under 1/5th of an inch. Ideally no cracks, full natural edge and flat.

There is a reason these things are not cheap. It is not self-evident how to make these and keep them nice and flat. Not being a woodworked I have so far stayed away. I DO have a thick Yew stumb laying around, fully dry now after spending 4 years in a shed. I still want this sliced up, and then sand them down & polish. But, besides sawdust toxicity & my slight allergy to Yew, the risk of warping is one that I do not know how to avoid.

 

[JoeWilson]

Under half an inch else it is just too thick. Smaller sizes typically are under 1/5th of an inch. Ideally no cracks, full natural edge and flat.

There is a reason these things are not cheap. It is not self-evident how to make these and keep them nice and flat. Not being a woodworked I have so far stayed away. I DO have a thick Yew stumb laying around, fully dry now after spending 4 years in a shed. I still want this sliced up, and then sand them down & polish. But, besides sawdust toxicity & my slight allergy to Yew, the risk of warping is one that I do not know how to avoid.

Thanks, that makes sense. One other thing I'm wondering is how do people typically use jiita. Are these purely for show/display? Meaning you would only take them out briefly when presenting the tree? I assume this is the case because otherwise, if it sat under the tree when you water it etc, it would warp after a few days.

Wood movement is unavoidable as the wood continues to breathe (gain and release moisture through the seasons), but there are some things you can do to mitigate it.

1. Make sure the wood is not only dry but also acclimated to the environment it will live in. If this is something that will spend most of the time in your house, before you mill it to the final size you want to bring it inside and let it sit for a few weeks, or if it’s a larger slab or stump, a few months, or even up to a year or two depending on the size. But generally, you should rough cut it beforehand so you don’t have to wait forever.
2. You can use a moisture meter and then look up a moisture equilibrium chart for your climate/humidity to make sure the slab is acclimated. This can be tricky if you're making wood products and selling them or giving them as gifts to people who live somewhere else. For example, if I mill a board in Denver, and give it to someone in Florida, the moisture content might double (from ~6% to 12%), and all bets are off. I would expect similar problems if you're buying wood from Japan and live in an arid climate, so if possible, it's best to buy wood products from somewhere that has a similar climate to yours.
3. Reducing the size gradually is a good practice. First, rough cut it (oversized) and make sure it's dry. Then let it sit for a while to release any stress and dry out further - the center of the wood generally being wetter than the outside. Then flatten the wood with a plane, planer, router jig, etc. You can let it sit again after this, and if necessary, flatten it one more time before you do the final sanding. This gives the slab plenty of opportunity to settle into its shape, so movement should be limited as much as possible. For thin slabs, a drum sander is great for bringing the board to final thickness, as you can take very light passes. If you don't have access to bigger machines, you might be able to find someone with a shop where you can rent time, or a maker space nearby. But there's always a way to do it with hand tools as well.
4. Some wood species are more stable than others. Clear, straight-grained boards tend to be more stable than curly or figured grain as well. Though sometimes burl, due to its wild, interlocking grain, can be quite stable, as the grain wanting to move in every direction all at once may neutralize the movement. Or not, maybe you'll have a burl slab where half of it is stable, and the other half isn't. It can be unpredictable.
5. There are some methods to chemically stabilize small wood pieces with a pressure pot. Basically, the water in the pores is plastized or replaced with some kind of resin, hardening the wood and making it more stable. This is kind of a nasty process and you're limited by the size of the pot, but it's a good way to keep wood flat for a long period of time.

 

[leatherback]

One other thing I'm wondering is how do people typically use jiita. Are these purely for show/display?

Yes.

I used one in a show this spring, and someone there kindly watered all the trees and accents. Water dripping out of the pots ruining my JIta and a few tables in the display. The Jita is beyond salvation, complately warped

Watering is an art, certainly in shows..

Often these are pretty well sealed and thus pretty inert to atmosphering humitdiity

 

[JoeWilson]

Yes.

I used one in a show this spring, and someone there kindly watered all the trees and accents. Water dripping out of the pots ruining my JIta and a few tables in the display. The Jita is beyond salvation, complately warped

Watering is an art, certainly in shows..

Often these are pretty well sealed and thus pretty inert to atmosphering humitdiity

Oh man, I would have been screaming internally.

I was looking into finishes a bit, and it seems like lacquer is traditional, but polyurethane is probably ideal. I've used that in the past for plant shelves in humid areas, and it works well. Which is a shame because I hate working with poly, but oh well.

I ripped a few slices last night. These are 1/2" thick right now, but will probably come down to 5-7mm or so when I surface them. 11.75x5.75" ~ 300x145mm, will shrink a bit when I square everything up. I'll let them sit for a few days and figure out a way to flatten them. My router jig is meant for thick slabs, so I probably need to build a little jig to hold them.

The last photo shows what it looks like bookmatched. I'm tempted to try one like this and cut it into a circle, I would probably get a ~10" piece out of it.

 

[JoeWilson]

Some burl cap slices. Is it good if it looks like the lovechild of Wisconsin and an oven mitt?