I've been making Deacon's Benches, using 3/4" white pine for the lid, and no matter what I do the lid warps. How do I keep the lid from warping, or get the warp out, and get the lid to lay flat? I would appreciate any tips on this. Thank you.
You failed to mention the width of the panel, so I'll assume it's 8" to 10". Rip it into at least 3 pieces and glue it back with the grain alternating. That should fix the problem after it's sealed on all sides.
Just want to underline Bob's second point, where he said--"sealed on all sides". Whatever coating or treatment you do to the top must be done to the bottom as well. The same number and type of coats. That way, you don't have more moisture from the atmosphere entering a lightly treated side and causing cupping. Wiley Horne