I cut a piece of 3/4" birch plywood about 10"x60". It will be the side
of a book case. If I lay it on a flat surface it has a slight hump in
the middle of about 3/16". Has anyone ever tried to undo this warp?
I have the board suspended between two saw horses with about 50 lbs of
weight on the middle. the weight flexes the board plenty, but when I
remove the weight it springs back. I left the weight on for 24 hours.
I also tried warming the wood with a heat gun. Anyone have any ideas?
do i have to leave the weight on for several days?
Note: This is the last time I buy ply at Lowes.
Imagine the time it took to get that warp just right. You're not going
to take it out in a day, maybe a week, put you'll probably need a few
A couple ideas:
1. Screw it in, as is. Sufficiently supported with screws, the warp will
effectively disappear. (I think this is the best option, but you might
be going for a different look from the back.)
2. Steam it to make it more receptive to being unwarped. Search on
"steaming wood" or "steam bending" for more information.
3. Let it sit, flat, for months. It might fix it, it might not. Do this
in an unheated building so your board will be subjected to more extremes
in humidity and temperature. (Why your board warped in the first place,
that is: humidity and temperature changes.)
Marching to the beat of a different drum is great... unless you're in
First, most any plywood will warp to some degree. 3/16" isn't much
warp, and should straighten out easily when it's applied to wherever
it's going to be used.
IMO you're very unlikely to be able to ever get it perfectly flat.
It's more apt to end up warped in the opposite direction when it does
change, if ever. If for some reason it's only going to be fastened on
two sides or in some way that won't pull the warp out naturally, then
you're probably best to figure some way to add runners to it to pull the
warp out. Although I can't imagine any place to use a piece of wood
that size where it wouldn't be well supported anyway, which normally
pulls out the warp when it's attached. It's just the nature of plywood
to warp unless you spend the extra money for the best grades. And how
you stored it, of course, dictates a lot of the warpage, too.
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