I'm working on a built in bookcase that's just under 8 ft high and 10" deep, made of popular. I picked up a load of 13/16 thick material which included several 8' long boards 11 to 12" wide. I ran these through my planer reducing the thickness to 3/4" but after a day or so a couple pieces warped across the width making them unusable for the sides of the case. I can reprocess the warped boards into shelves so the material won't go to waste. However I'm new to wood working, particularly with projects of this size, so I wonder did I chose the wrong material, process it incorrectly or perhaps this outcome is to be expected occasionally?
Thanks
Robert