On Sunday, April 10, 2016 at 1:28:44 PM UTC-5, Sonny wrote:

I suppose your last option may be to remove the panel, moisten the raw (bottom) side for a day or so, then allow to dry in a "clamped" reverse curved position (over correct the curve, a bit), to correct the bowing... and hope that does the trick. I would suspect the wood is air dried, but sometimes old "cured" air dried wood acts as if it's kiln dried and is not always as bendable/reshapeable as new/newer air dried wood. I don't think you would damage the panel if you gave this a try.

If you do give this a try, then, as you're clamping the panel, listen closely for any small, minute sounds of cracking. Tiny cracking sounds indicate it's not bending properly, i.e., not bending as typical, as readily as, air dried lumber does.... or as steam bent lumber does. Even trying to steam bend old cured air dried lumber doesn't always work.... you can hear small cracking sounds, when trying to steam bend old cured air dried lumber. It doesn't steam bend properly, similarly as when trying to steam bend kiln dried lumber.

The bow in your panel doesn't appear to be too significant. You shouldn't have to recurve, over correct, the bowing too much, so a wet-bending option may work.

Sonny