PLYWOOD

Plywood is a composite material, although we often consider it as a traditional working material. It is composed of individual plies / veneers of wood. It is very strong due to the way the plies are put together. The grain of each ply is positioned at ninety degrees to the pieces of ply above and below it. The plies are glued together with synthetic resin, making a very strong composite material. Furthermore, plywood is usually constructed so that an odd number of plies are used. Plywood is less likely to warp or split, due to this construction.
Manmade boards of this type are supplied in a range of sizes and thicknesses. This is an advantage compared to natural woods, as manmade boards can be manufactured so that they are extremely wide. This makes plywood a popular material in the construction industry.

Softwood ply tends to be used in the construction industry for walls, roofs and floors.
Hardwood ply tends to be used quality laminate flooring, kitchen units and some furniture.
Marine plywood is used in boat hull construction. It is specially treated so that it is water resistant .

The diagram below, shows the individual layers of plywood, called plies or veneers. Study the diagram, especially the grain. Each ply has its grain running at ninety degrees to the next layer, as indicated by the arrows..