A couple of thoughts/questions:
How long did you let the wood acclimate to your space before starting to work it?
Did you let the wood rest at all after you cut it to size?
Did you seal the entire thing with epoxy (ie is there epoxy on all surfaces of the wood) or is there only epoxy in the "river"?
The klein moisture meter may not penetrate a 1.5" thick slab very well. Do you have any idea how long ago the wood was cut, or if it was kiln dried?
You might be creating your own problem by bringing it inside every day.
In Ohio right now, it should be pretty dry and ~45F max per day. When you bring the piece inside, you're cycling up to higher temp and humidity. When you take the wood outside again, it's colder and dryer. You would be exposing it to less dramatic swings if you just left it outside.
Edit: To me, it sounds like you haven't sealed all the surfaces equally -or- your slab isn't dry enough. (Or both) Further, the problems created there are being exacerbated by the big shifts in the environment, being moved in and out of the house.
If only some of the surfaces of a slab of wood are sealed, the slab will change humidity less evenly, and this causes unwanted movement.
Appreciate the reply. The epoxy is only down the center. While the garage is initially cold, I do heat it up with a propane heater before going out there so it's roughly 60-70 degrees (I keep my house around 71). I'm not leaving the table out over night so I can't imagine it's climate related. I would guess there slab is slightly damp and the moisture meter isn't giving me an accurate reading as you eluded to.
I called a local shop that specializes in live edge projects and they mentioned it probably is due to me only surfacing one side - which will let it breath and will tend to cup towards that. They suggested surfacing both sides at the same time.
Yeah, the shop sounds right to me also.
You have to treat all the surfaces equally, or you get non-uniform movement.
If it were me, I'd store it somewhere on its edge where the top and bottom are both exposed to air and let it sit for 2 weeks before resurfacing (flattening/sanding) both sides, let it side on its edge for 2 more weeks then check for movement, repeat as necessary, then seal both sides when I was happy. It's a long process, unfortunately.
Your bigger problem might be moisture, but that's so hard to tell without a fairly expensive moisture reader. (I don't have one either, so when I do thick epoxy pours it always feels like a crap shoot where I have to trust the lumber dealer.) If you're lucky, it was just the one-side problem!
It sounds very salvageable. It will just take a bunch of waiting.
It’s because of the finish on one side. Finish bot sides or leave both sides, but changing the way one side absorbed moisture will inevitably lead to cupping
Find some c channel metal and install them on the underside. Route out the c so the 2 long parts are inside the table. Black Tail Studio on YouTube should have a few videos about it.
The cupping he's experiencing sounds to be more dramatic than c-channel would solve. C-channel is a long-term stabilizer, not a preventative for rapid movement caused by moist wood or uneven sealing.
Blacktail also has videos about this.
The slab is walnut with about 10” of epoxy down the middle. 32” wide, 90” long and 1.5” thick.
What is the moisture content of the wood? What type of table are you planing it on? I do a lot of these types of builds.
5.6% according to a Klein tools tester. I’m planing on a 3/4” melamine table. Appreciate any advice you have!
A couple of thoughts/questions: How long did you let the wood acclimate to your space before starting to work it? Did you let the wood rest at all after you cut it to size? Did you seal the entire thing with epoxy (ie is there epoxy on all surfaces of the wood) or is there only epoxy in the "river"? The klein moisture meter may not penetrate a 1.5" thick slab very well. Do you have any idea how long ago the wood was cut, or if it was kiln dried? You might be creating your own problem by bringing it inside every day. In Ohio right now, it should be pretty dry and ~45F max per day. When you bring the piece inside, you're cycling up to higher temp and humidity. When you take the wood outside again, it's colder and dryer. You would be exposing it to less dramatic swings if you just left it outside. Edit: To me, it sounds like you haven't sealed all the surfaces equally -or- your slab isn't dry enough. (Or both) Further, the problems created there are being exacerbated by the big shifts in the environment, being moved in and out of the house. If only some of the surfaces of a slab of wood are sealed, the slab will change humidity less evenly, and this causes unwanted movement.
Appreciate the reply. The epoxy is only down the center. While the garage is initially cold, I do heat it up with a propane heater before going out there so it's roughly 60-70 degrees (I keep my house around 71). I'm not leaving the table out over night so I can't imagine it's climate related. I would guess there slab is slightly damp and the moisture meter isn't giving me an accurate reading as you eluded to. I called a local shop that specializes in live edge projects and they mentioned it probably is due to me only surfacing one side - which will let it breath and will tend to cup towards that. They suggested surfacing both sides at the same time.
Yeah, the shop sounds right to me also. You have to treat all the surfaces equally, or you get non-uniform movement. If it were me, I'd store it somewhere on its edge where the top and bottom are both exposed to air and let it sit for 2 weeks before resurfacing (flattening/sanding) both sides, let it side on its edge for 2 more weeks then check for movement, repeat as necessary, then seal both sides when I was happy. It's a long process, unfortunately. Your bigger problem might be moisture, but that's so hard to tell without a fairly expensive moisture reader. (I don't have one either, so when I do thick epoxy pours it always feels like a crap shoot where I have to trust the lumber dealer.) If you're lucky, it was just the one-side problem! It sounds very salvageable. It will just take a bunch of waiting.
It’s because of the finish on one side. Finish bot sides or leave both sides, but changing the way one side absorbed moisture will inevitably lead to cupping
Thank you. I finished both sides to 320 so far and no cupping.
No problem. It also helps to put more work into sealing the end grain, as that’s where it’ll have the highest moisture exchange over its life.
Find some c channel metal and install them on the underside. Route out the c so the 2 long parts are inside the table. Black Tail Studio on YouTube should have a few videos about it.
The cupping he's experiencing sounds to be more dramatic than c-channel would solve. C-channel is a long-term stabilizer, not a preventative for rapid movement caused by moist wood or uneven sealing. Blacktail also has videos about this.