Plywood is a composite material manufactured from thin layers, or “plies”, of wood veneer that are glued together with adjacent layers, having their wood grain rotated up to 90° to one another.
All plywoods bind resin and wood fibre sheets (cellulose cells are long, strong and thin) to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across all directions.