What makes plywood strong and stable?

Plywood's strength and stability are primarily due to the gluing of layers with concentric grain direction. This method involves arranging the wood layers so that the grain of each layer runs in alternate directions. As a result, the opposing grain patterns help counteract the shrinkage and expansion that can occur with changes in humidity and temperature. This cross-graining reduces the likelihood of warping or bending, making plywood more resilient compared to solid wood. The adhesive used in bonding these layers also contributes to the overall structural integrity, allowing plywood to withstand stress and loads effectively.

The thickness of each layer does play a role in how strong the plywood is, but it is the orientation of the grain that is crucial for stability. While using solid wood pieces can provide strength, solid wood has a tendency to warp, split, or bow over time, which plywood effectively mitigates. The type of wood used is relevant for specific properties like weight and appearance, but it is the configuration and adhesive of the layers that are foundational to plywood's robust characteristics.