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I bought some very nice big leaf maple sides and backs earlier this year thru one of the OLF auctions. They were flat when I received them but after two months sitting in the box in my closet, this is what happened. The redwood top pieces I bought at the same time stayed flat.

I had a senior moment combined with a brain fart and didn't even think of doing anything to keep them flat.

What do I do to get them flat again so I can start thickness planing them this spring?

No big deal, mine did that too. Put in a room where u can control humidity and lay flat with even weight on top.

The concaved side is were most of the moisture loss is.
As stated -sticker them on all sides and if you want to see a wonderful thing then sprits the concave side with a very small amount of water.
That side will expand again-and all will look fine.
I would use a sander NOT a planer on that wood and most figured ones.
The rollers will flatten the wood -especially when it gets thinner.

As long as it's not cracked your fine-just treat it carefully.
Mike

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Mike Collins

I plan to use a hand plane with a toothed blade then a regular plane. I just picked up a used Stanley #5 jack plane to use for the toothed blade.

I had the same problem 2 guitars ago and other forum guys at the time suggested using a regular cloths iron to flatten the maple and it worked. I had to do it several times until the wood stablized. My wife was not thrilled but it was just maple and did not stain the iron. The sides tried to cup again when I was bending on the Ibex bender but it turned out okay.
Michael

I think what Mike Collins was saying is do not use a tool to "flatten". Maybe I am wrong...

Mike

A senior moment AND a brain fart I can relate....

Just clamp them together the way you have them in the picture and they will flatten out. Keep a eye on them so they don't go the other way. No need to start wetting and ironing just yet.
Link

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Cut to size.....Beat to fit.....Paint to match.

If you want to use them soon, what Mike C. said will work great. You'll be amazed how
quick the concave side will straighten out with a little moisture applied. If you're going
to clamp them, be sure to put some stickers between the pieces. If you clamped them
directly, the inside surface (which needs more moisture to expand), will have a hard
time finding it, while the outside is still exposed. I'd probably clamp them with the convex
sides together, so the outside surfaces can pick up moisture.Be careful to get it flat before
planing. I've put pieces like that through my 16-32 with good results, but the pressure rollers are
flattening it in that case. If you plane the high points off both sides of each piece without the wood
being flat, you'll have taken it off quarter a small amount.

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Gene

Politicians and diapers must be changed often, and for the same reason- Mark Twain

I experienced this and at first I was concerned that they would never straighten out.

I spay both sides with water, put stickers between them and in a short while they are perfectly flat. I found that spraying the cupped (dry) side just reversed the cupping !

If you leave it for any length of time and the RH is up and down one side will evantaully dry out more than the other and you will get the cuppinmg back again.

John

Here is an extreme example.

A few years ago, I bought a set of curly BRW that had been left unstickered and was cupped and potato chipped. The wood was 1/4" thick, and resisted straightening. I did not want to heat it, because the ends were waxed, and the heat would draw wax into the wood permanently. I soaked it three days in water, hoping to sticker it under weight. After three days, it was still so stiff that I cold not flatten it, and I do not have enough large clamps. Then, I was going to set up a vacuum bag to get enough pressure. I poked aroung several days. When I went to get the wood out of the water, it was dead flat. Then I just stickered it with weights as usuall, and all is fine. It took not only some moisture, but a lot of moisture and a lot of time (7-10 days) and it just went back to the fresh-cut shape all on its own.