How do I correct extreme crossgrain cupping?

Question

I was staining a set of pieces of unfinished pine for a dresser (ikea furniture) on my rooftop. First coat was put on last night around 9pm, and I was planning on doing the second coat this morning and letting dry outside all day.

One freak thunderstorm later, I'm rescuing the pieces from the roof at 5am. Dried them off as well as I could with rags and put them inside on cardboard.

However several of the large pieces are extremely warped in the cross grain direction.

Is there anything I can do to salvage these pieces?

Answer 1

You can get this flatter certainly, but you may not be able to get them totally flat or to get them to stay that way permanently — wood that has bowed can show a tendency to want to return to that shape.

One method is to wet the cupped side and put the wood out in the sun to dry. A variation of this is to wet both side but have the wet side sit on grass where it'll dry much more slowly. I've tried both (not on anything this extreme!) and I'm not sure there's a clear winner in terms of effectiveness.

Another method doesn't involve drying outdoors but is a little more involved. You'll need a few clamps and some means to raise the edges of the boards up a little so the centre can bend downwards slightly. You thoroughly saturate the wood, front and back, and then clamp it in stages until you get it slightly beyond flat, i.e. cupped very slightly in the opposite direction to how it is now. Then let the wood dry overnight or longer.

Note: you must use scrap blocks under the clamps to help prevent marring the wood, this is soft wood anyway but it'll be even more prone to bruising when wet.

Answer 2

Adding to Graphus's answer, you can also cut the board down the middle run them through a jointer and reglue them back together. If you can flip one side over for the join, you will reduce the max bow it is capable of.