I stack 1/2" baltic plywood vertically in a rack. The top of the plywood is “sloped” leaning against a wall. This “slope” or angle can vary from approximately 60° to almost vertical depending on the amount of wood stored in the rack. After about two weeks the plywood has a tendency to have a curvature towards the wall. I store at 62°F – 65°F and 80% – 89% RH but it always warps in the same direction. Is this due to movement of the glue due to shear from wood expansion of the outer layers? — Richard Cowmeadow

Bob LaCivita replies: The effect is caused by gravity. Plywood should be stored horizontal flat. Most of us do not have the space to do this. I store plywood up either standing on end or edge at as close to 90 degrees as possible. Veneer core plywood will warp to some degree because the core veneers are not the same thickness due to cutting, pressing and in some cases, sanding. The face veneers are also sanded and are not equal. the slightest difference will cause the sheet to warp.

Wood