Warped plywood

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Forum topic by WoodNuts posted 03-09-2011 12:22 PM 2872 views 0 times favorited 7 replies Add to Favorites Watch
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74 posts in 2368 days

03-09-2011 12:22 PM

Looking for your techniques on how you straighten warped Baltic Birch plywood in any size > 20”sq.
Thanks for any/all replies…

-- ...there's a fix fer dat...

7 replies so far

View CampD's profile


1459 posts in 2906 days

#1 posted 03-09-2011 02:34 PM

Baltic birch is the most stable ply I know, must have picked up a LOT of moisture to warp.
You can try and stack it flat with a lot of weight of top and time will tell

-- Doug...

View Sawkerf's profile


1730 posts in 2488 days

#2 posted 03-09-2011 04:55 PM

I would either start over with a better grade of ply, or assemble your warped pieces so they get straightened out – and hope that the additional stresses relieve themselves without wrecking whatever you’re buildig.

-- Adversity doesn't build reveals it.

View Rick  Dennington's profile

Rick Dennington

5103 posts in 2614 days

#3 posted 03-09-2011 05:10 PM

Greetings Woodnuts,

The best way I’ve found to help warped ply is to WET it down really good all over....anything up to a 4’x 8’.

Take a rag, soak it in water, and wipe the ply down good on both sides….... Lay it down flat, and stack more ply on top of it to keep it flat…..if you have an extra sheet or two….

  • If not, weight it down the best you can with something heavy like cauls and clamps….cinderblocks, etc….* Let it dry really good for a couple of days and check it…..if flat and weighted, it should be straight….

    After it’s dry, use ASAP…....I’ve done it a 1/2 dozen times….works for me….....hope this helps.

-- At my age, an "all--nighter" is not having to get up and pee...!!!

View Will Mego's profile

Will Mego

307 posts in 3132 days

#4 posted 03-09-2011 07:42 PM

yeah, I think that the odds aren’t with you, but the only decent way is like Rick said, wet BOTH sides well, then clamp, stack, whatever to get it flat and straight…think of it as cold steam bending in a way. Good luck though!

-- "That which has in itself the greatest use, possesses the greatest beauty." -

View Mike Gager's profile

Mike Gager

665 posts in 2687 days

#5 posted 03-10-2011 08:00 PM

if the piece you are using wont be seen in the final product, such as an interior panel or even if only one side will show you can cut relief kerfs on one side of the panel, that should flatten things out

similar idea to kerf bending plywood except you are trying to take the bend out

View Bill White's profile

Bill White

4405 posts in 3380 days

#6 posted 03-13-2011 08:12 PM

A really hot fire will solve the problem. Get it roaring, then throw the crappy plywood on top. Step back, get a beer, and watch out for any stray sparks.


View jusfine's profile


2405 posts in 2345 days

#7 posted 03-13-2011 08:22 PM

I had some BB stored for a couple years and it was quite warped too, but it was in the shop and didn’t get any moisture on it.

I ended up buying new full sheets and cutting the other warped sheets up for smaller pieces. Still caused me some grief with my outfeed table construction.

All the Best!

-- Randy "You are judged as much by the questions you ask as the answers you give..."

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