Stop buying thin-ass, end-grain cutting boards. Wood cutting boards will be damp, it's unavoidable, but they shouldn't ever warp unless they are too thin. Get a nice thick long-grain board, or just get a plastic one. All the kitchens I've worked in at 3/4 star hotel and resort restaurants use plastic boards for most things, and usually have one big(real big) and thick long-grain board that could survive a nuclear blast.