Plywood is a common material with myriad uses, including in construction and furniture and cabinet building. It is most commonly sold as a 4-by-8 foot sheet in thicknesses ranging from 1/8 inch to 3/4 inches thick.
Plywood is made of layers of wood laminated together with glue. The direction of the wood's grain alternates from layer to layer, which produces a stable end product.
There are two main types of plywood; softwood and hardwood. Softwood plywood is made from fir trees such as spruce and pine. Hardwood varieties are made from oak, birch, maple, mahogany and others.
Plywood is graded by interior and exterior layers, the type of glue used and whether it can be used outdoors. The type of wood used, the smoothness and the wood's appearance contribute to its grade. A smooth side suitable for staining has an "A" grade, while a side unsuitable for appearance has a "C" grade.
Plywood has a long history dating back to ancient Egypt and China. Plywood was first introduced into the United States in 1865 when a patent for it was filed for the first time. The patent went to John K. Mayo from New York.
World War II
In World War II, plywood was a strictly controlled product. The military used plywood for everything from constructing barracks and building gliders to plywood assault boats used to cross the Rhine river.
Plywood gave rise to other products such as orientated strand-board, or OSB, which is made from small, thin pieces of wood glued together. Other products include laminated veneer lumber, or LVL, and particle board.