Warped plywood

[Raymond Fries]

Anyone know of a way to flatten warped plywood? Most of the 2' x 2' x 1/4" stuff at the big box stores is warped. I cut these into smaller pieces for projects and I need them to be flat.

Ideas?

[Sam Murdoch]

Sorry, I can't even imagine how to do this. Will be reading the replies for my own edification.

[Andrew Hughes]

If you had a stack of them and a full grown African elephant sit on the stack I bet they would be flat.:)

['Jacques Malan']

Don't buy it.

We have got a big press at work, and I tried a few times to put plywood in there to flatten it, and it has never worked. Not even 3mm, not even for 3 weeks.

[Jim Foster]

Most plywood that's warped at the big box stores is like that due to manufacturing and material issues. Even if the layers are balanced in grain direction, if the grain is not straight and very exact on direction, you will get warping that does not go away.

[Jim Andrew]

If you build a drawer, and put the plywood in a groove, the groove will hold it fairly flat. I built cabinet doors from plywood probably 40 years ago, and sometimes a door would warp, and I would have to replace it. If I let it lay around till it was dry, it would go back flat. So they make some plywood with green wood.

[Mark Bolton]

Be a bit more work and money (good stuff always is) but you may look into sourcing some material with a different core. Look for a local distributor or online. If you really want/need flat a little freight and added cost will get you there.

[Richard Coers]

I think you'll need a different material if you need it really flat. No idea what smaller pieces mean, but I would suggest solid quartersawn wood. Does the plywood you are looking at have the same veneer on front and back? Plywood must be balanced to stay somewhat flat, but todays plywood will always be questionable.

[Mark Bolton]

If the material is coming from the borg in the first place I would think tracking down some maple, birch, or whatever, MDF core would get flat enough for most anything.

[Bill McNiel]

Apple ply or baltic Birch or MDF core. The stuff at the box stores is not worth a penny for most cabinet work.

[Jeff Duncan]

I haven't seen really flat plywood from a Borg or from my wholesalers, and I doubt I ever will. If you need it to be veneer core, (vs mdf core), and need it truly flat, the only thing I can suggest is making your own. Assuming you need the quantity and quality to make it worth while, you can press your own veneers controlling the quality of the core and getting nice flat panels. Of course it's going to be a very expensive endeavor:o Other than that…….I got nothing.

good luck,
JeffD

[Raymond Fries]

Well I was afraid this would be the case. I guess I will have to go with the usual slim pickins...

Maybe someone else will come along with something creative.

Thanks for your thoughts.

[Jim Foster]

There are plywood stores. You might find a much better solution at a distributor/reseller that specializes in plywood.

[glenn bradley]

As stated, the big box store is not where you want to buy things of this sort. Medium density overlay is generally quite flat but, I do not know about it in 1/4". Tempered hardboard and MDF in 1/4" is pretty flat stuff if that material would suit your use.

[Mark Bolton]

What is your specific use/need for flatness? That may help narrow it down. I'd imagine any manufactured core (if you don't need exposed veneer edges) would be flat enough for any non scientific use.

[John Piwaron]

If you already own that plywood and it's not flat - you're probably out of luck. I once had some like that. Bought from the Borg. I did get it flat. But not in a way that's probably going to be of use to you. I used it for shelving. But I made a frame for underneath it then I glued and screwed it to that frame. Great! Now it's flat. But I know it doesn't want to be.

Nowadays when I want flat(ish) plywood laid up of veneer, I go to a traditional lumberyard for it. It may not be absolutely flat (but what is?) but it *is* a lot better than what the Borg sells.

MDF is pretty flat. Maybe you could use that.

[Steve Rozmiarek]

I've heard that if you lay it convex side down on the lawn for a day, it will pick up enough moisture on one side to flatten. If it's the same as the junk I see at my local big box, you may need to run the sprinklers for a few days too....