I build some shelves in a small area in a basement bathroom. My wife wanted the wood to be natural. I used Popular 1x2 for the face and the quarter-round. I used Birch for the shelves themselves. My question is, in a steamy bathroom environment will the wood age well? Or, will the birch (similar to a cabinet grade of birch) try to separate? My option would be to seal the wood with some type of sealer, perhaps a satin varnish. I would like to leave it unfinished if you think it will not warp and splinter.