How do I flatten wood?

Crack can be filled with two part epoxy once it's flattened. Support it on it's ends with 2X4s, cinder blocks, or anything solid with the bend up. Wet the board almost to saturation. Weigh down the center of the board, cover with plastic sheeting and let sit. It will take a while for it to flatten. Check every few dys to see how it's coming along. Keep it wet the whole time. Once it looks good let it dry completely

Hi Patti - I think this might be able to help you: https://www.ehow.com/how_4529689_straighten-warped-piece-wood.html

You co7ld try to put a damp towel on it and lay something on top not to heavy and wait a week then do again and add more weight and weight a week keep doing that till you get it the way you want it because remember it took a long time to get like that so it will take a long time to fix

I agree with Kathy on this one: If you need it fast you need to consider replacing that wood because inverse warp is a science in itself that most underestimate and mess it up.

Besides, the warped resource is simply better to use in a Craft somewhere else where a Warped Resource is more essential to the much more attractive Design, like: trim for a Corner Shelf.