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Location: Central Indiana - Kokomo Area
Working on the set of kitchen cabinets.
Two sections they went with 1/4 sawn WO.
On the Island, they went with walnut.
I shop cut the veneer, sanded them to a hair more than 1/16"
I used Unibond 800 glue.
I used 7 ply 1/4" plywood as the core and of course veneered both sides.
I book matched the veneer.
The oak door panels came out great, nice and flat. With it being 1/4 sawn, that did not surprise me.
The walnut panels with highly figured front face veneer and just normal veneer on the back came out of the vacuum press looking good.
It did not take long before the walnut panels started to bow and warp.
In both the width and height the panels cup towards the figured face.
One set of panels approximately 17" wide cup enough that if you put a straight edge from side to side, there would be almost a 1/2" gap in the middle.
I tried to put a panel on a jig that bent the panel the opposite of the bow. Left the panel in there for 2 1/2 days.
When I removed it, it was flat for about 4 hours!
Some door panels are 18" wide and 28" high. They need to be flat!
First of all, I can not understand why this happened. Any speculation?
All I can come up with is I should have made the veneer maybe closer to 1/32" instead of the 1/16".
Should I have used MDF instead of plywood?
Second, any good ideas that would flatten the panels permanently?
Any information or help will be greatly appreciated!
Toney
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Threads: 2
Joined: Oct 1999
01-18-2025, 09:20 AM
(This post was last modified: 01-18-2025, 09:22 AM by Tapper.)
(01-17-2025, 09:45 PM)iublue Wrote: Working on the set of kitchen cabinets.
Two sections they went with 1/4 sawn WO.
On the Island, they went with walnut.
I shop cut the veneer, sanded them to a hair more than 1/16"
I used Unibond 800 glue.
I used 7 ply 1/4" plywood as the core and of course veneered both sides.
I book matched the veneer.
The oak door panels came out great, nice and flat. With it being 1/4 sawn, that did not surprise me.
The walnut panels with highly figured front face veneer and just normal veneer on the back came out of the vacuum press looking good.
It did not take long before the walnut panels started to bow and warp.
In both the width and height the panels cup towards the figured face.
One set of panels approximately 17" wide cup enough that if you put a straight edge from side to side, there would be almost a 1/2" gap in the middle.
I tried to put a panel on a jig that bent the panel the opposite of the bow. Left the panel in there for 2 1/2 days.
When I removed it, it was flat for about 4 hours!
Some door panels are 18" wide and 28" high. They need to be flat!
First of all, I can not understand why this happened. Any speculation?
All I can come up with is I should have made the veneer maybe closer to 1/32" instead of the 1/16".
Should I have used MDF instead of plywood?
Second, any good ideas that would flatten the panels permanently?
Any information or help will be greatly appreciated!
Toney
No expert in this area, but in my experience thin MDF is much more stable than thin plywood. Sorry, can't think of anything that will flatten the panels other than a thicker backer material, which will probably not work in your application.
Doug
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Location: Lewiston, NY
(01-18-2025, 09:20 AM)Tapper Wrote: No expert in this area, but in my experience thin MDF is much more stable than thin plywood. Sorry, can't think of anything that will flatten the panels other than a thicker backer material, which will probably not work in your application.
Doug
I agree. MDF with epoxy glue or polyurethane glue (no water) would have the best chance of staying flat.
John
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Joined: Jun 2003
01-23-2025, 11:21 AM
(This post was last modified: 01-23-2025, 11:23 AM by rwe2156.)
The backer and the show veneer was not balanced. If the backer veneer isn't the same thickness that can be a problem. Also, shop sawn veneer may not be totally acclimated so the not only will the glue pull, the veneer will shrink.
Backer veneer is more accurately called balance veneer, and it doesn't always balance the panel. I've had this happen many times. I've attributed it to the difference in grain or strength between the backer and the show veneer.
1/4" panels are more prone to cupping and a lot harder to keep flat. I don't think MDF vs. ply matters. It happens enough that I hold larger panels in clamps and cauls until I can get them installed in the door.
If the cup can be flexed out fairly easily and the doors are stout enough I would install them. I'd keep them clamped flat for a couple days prior to installation. I usually get some finish or sealer on them and they go back in the cauls when dry. After they're installed I keep my fingers crossed. I think you'll be OK.
No expert, but this is what I've concluded based on my experience.
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01-23-2025, 11:29 AM
(This post was last modified: 01-24-2025, 07:42 AM by Tapper.)
(01-23-2025, 11:21 AM)rwe2156 Wrote: The backer and the show veneer was not balanced. If the backer veneer isn't the same thickness that can be a problem. Also, shop sawn veneer may not be totally acclimated so the not only will the glue pull, the veneer will shrink.
Backer veneer is more accurately called balance veneer, and it doesn't always balance the panel. I've had this happen many times. I've attributed it to the difference in grain or strength between the backer and the show veneer.
1/4" panels are more prone to cupping and a lot harder to keep flat. I don't think MDF vs. ply matters. It happens enough that I hold larger panels in clamps and cauls until I can get them installed in the door.
If the cup can be flexed out fairly easily and the doors are stout enough I would install them. I'd keep them clamped flat for a couple days prior to installation. I usually get some finish or sealer on them and they go back in the cauls when dry. After they're installed I keep my fingers crossed. I think you'll be OK.
No expert, but this is what I've concluded based on my experience.
This could be true if you're speaking of high quality Baltic Birch plywood IMO. In my limited experience the general run-of-the-mill thin plywood is not nearly as stable as MDF.
Doug