I'm making a set of bespoke skinny (5" deep) 'picture gallery' shelves - 4ft wide. Whilst cutting and drilling them I've become aware of just how moist/resinous the wood (pine) is. This morning on looking at them I can see the wood has a small camber. Unfortunately, I'm placing these over a radiator. I know I should probably have made them from mdf but I didn't want to work with that material. Will painting them seal the moisture in & keep them mostly flat? I intend to prime/oil eggshell the shelves all over. Will this seal the moisture in & keep them relatively stable or will they still dry out terribly & warp? I have a sinking feeling I'm learning an amateurs mistake. Planks of modern fast-grown pine are always going to have a radius to them.
Secondly, I may make a narrow faux console to go over the radiator before the winter season. Any thoughts on how this might affect things?