I have a pierce of 3/4 plywood, about 5'by2', currently the back of a desk hutch. Once upon a time, it was a headboard, but it got cut down when we "downsized" and 'tad-dah!" I had the back piece and the side piece uprights.
But it was warped. In both directions.
Any suggestions for "straightening a sheet of plywood?
(I know, I could just find the "flattest" part and cut that out)
Do you have anything heavy, such as a stack of drywall sheets? Last time, I stacked about 20 panels of drywall on some warped plywood, and when I came back to the house project a couple of weeks later, it certainly made an improvement. I'm sure that a number of 80# bags of concrete would do the trick, also.
Years ago, I know that they steamed wood to bend it into shapes for intricate woodwork. I surely can't say that I've tried that method.
Probably if you soaked it in water for a while, and clamped it in an appropriately size improvised vise (with 1 or perhaps even 2 pieces of
3/4" plywood on each side, and plenty of clamps (bolts might help too)), and let it dry, then that would most likely flatten it out to a great deal. However, I have no ideal "how long" this fix would last. If you have high humidity, it might not last long. To be honest, I would probably replace the piece, and never look back! You might experience better results with Baltic Birch plywood ($$)--I believe it is usually sold in 5'x5' sheets. But I have no experience or expertise trying to what you are trying to do. Good luck! A before and after picture would be interesting.P.S. The "floor" of the cabinet under my kitchen sink has similar, possibly even more extreme, warp-age. But since She caused the problem by negligence, and since it is usually out of view, it is not close to the top of my list of "home projects for me". Someday I may replace it--though I anticipate that I will need to replace it in two pieces instead of just one (I'll almost surely have to remove it that way too!). Now, please don't feel bad that you reminded me about this! ; )
They still do that to shape wood for things like acoustic guitar sides (think about how it needs to curve like an "S").
I have affirmed who does that. Not sure he has a setup which can "scale" B-)
Hmmm, I think I'll just look into a) is there a 32" stretch which is "mostly flat"? or b) what can I find in "fall down" bin at BigBoxInc.
Don't hesitate to borrow a level to use as a straight-edge from another aisle of the store. Good luck with your project!
Warped plywood is often caused by unequal moisture content across both sides. See if there is a grade stamp on the back/bad side of the plywood. If you see something like ABX or BCX or CDX, or the word Exterior appears, it has exterior glue and can be dampened. If it has a grade stamp indicating Interior use ignore the dampening directions here and try the flipping part. As this started life in furniture there is a good chance it doesn't have exterior glue...
If you dampen the concave side, and place that side down on a flat surface, it may straighten itself out in a few days. Putting a blue tarp or plastic sheeting under it will help retain the moisture (keep the "floor" from sucking moisture out of the plywood). Sometimes just flipping a sheet over and exposing "the other side" to the same conditions as the "first side" is all it takes to equalize the moisture content. Note that 3/4" will generally take a bit longer to normalize than 1/2".
Bill snipped-for-privacy@att.net on Tue, 17 Jan 2023 20:21:24 -0500 typed in rec.woodworking the following:
For what I want to do "eye ball" will do.
John Grossbohlin snipped-for-privacy@gmail.com on Tue, 17 Jan 2023 18:20:40
-0800 (PST) typed in rec.woodworking the following:
I'm not sure where it "started" life. This was part of a collection of "obtanium" (Things found which might be good for something some day.)
The concave side had a really thin piece of "very nice wood" glued to it to make the plywood "look nice" on the side we would see. I have pondered if that might have been a problem, but "Nope it would have warped it the other way. Now I am wondering if it might have absorbed moisture on that side? If I leave the unfinished side facing the window, will it dry out enough? Is that likely to happen in Seattle, in winter?
At this point I'd try it and see what happens!
John Grossbohlin snipped-for-privacy@gmail.com on Wed, 18 Jan 2023 05:54:01
-0800 (PST) typed >> John Grossbohlin snipped-for-privacy@gmail.com on Tue, 17 Jan 2023 18:20:40 >
Easiest option. Now all I have to do is wait for the sun to shine.
5' x 2'?
Go to a home center and get a full sized sheet.
Then you'll have an 8' x 4' sheet of warped plywood. ;-)
You only have to see 1 side right?
Is there any angle iron or similar in your obtanium vault?
Mount the plywood on something straight and stiff that would force it back to flat.
Maybe use some decorative bolts or other means to make the mounting hardware seem like a design feature.
Have you seen the price of plywood??? B-) That's why I'm reusing it.
Snerk.
Reminded of the cartoon of the two welders at a Modern Sculpture Exhibit. "Sure it's Art. But can you really say that it is welding?"
At best.
Lemmee see ... I know I have some channel AL from some place.
Or, I could just work the warp into the design, then make allusions to the extraordinary effort it took to get just the right amount of curve into the wood for this effect. "It's not a bug, it's a feature!"
NOT A GOOD IDEA
and clamped it in an
Is this either?
You wouldn't get it wet? My understanding is that water makes wood more flexible. I know there is some glue in plywood, but I didn't say to soak it until it fell apart! : ) I was the one who also advocated simply replacing it--the wet-flex-fix is a last ditch effort!
But you did say soak it "in" water, and who is to say how much is enough and how much is too much If not in a mold I would fear de-lamination. AND the OP said that it was once a headboard so it likely had a nice veneer with a finish on it. Most if not all bending I have seen was with steam and molds on unfinished plywood/wood.
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