A: I'm staining and sealing some beaded plywood for indoor use. Is it necessary to stain/seal the back of each piece for expansion and contraction?
Plywood is already a dimensionally stable product-- if you are putting it near a shower it would be a good extra precaution, but if it will not be near moisture -- it is over kill. One note-- try not to install MDF paneling in a Bath. MDF stands for medium density fiberboard. Basically it is cardboard-- it is usually the least expensive paneling -- and has a brown or gray back.
I dont think you need to worry that much about the backsides. If its going in a bathroom, then yes, I would advise that all sides and edges be sealed. However, I think you will be fine in a normal interior application to just stain/seal the side that is showing.
I would say yes to applying the sealer to all six sides and no to staining all six sides. This can be as simple as staining your exsposed sides first and then apply your clear protector coat to all six sides.
I have been reading the answers & always thought you should seal the back.....
I am putting this on my cathedral ceiling soon between my handcrafted beams and "assumed" it should be sealed on the backing...........was I wrong?