plywood

A common reason for using plywood instead of plain is its resistance to cracking, shrinkage, twisting/warping, and its general high degree of strength. In addition, plywood can be manufactured in sheets far wider than the trees from which it was made. It has replaced many on applications for these reasons. Softwood plywood is usually made either of Douglus fir or spruce,pine and fir(collectively known as spruce-pine-fir), and is typically used for construction and industrial purposes.Hardwood plywood is used for some demanding end use. Birch plywood is characterised by its excellent strength, stiffness and resistance to creep. It has a high planar shear strength and impact resistance, which make it especially suitable for heavy-duty floor and wall structures. Oriented plywood construction has a high wheel carrying capacity. Birch plywood has excellent surface hardness, damage and wear resistance. High-strength plywood, known as aircraft plywood, is made from mahogany and/or birch, and uses adhesives with increased resistance to heat and humidity. Marine plywood is specially treated to resist rotting in a high-moisture environment. Marine plywood is frequently used in the construction of docks and boats . Other types of plywoods are fire retardant, moisture resistant, sign grade, pressure treated, and of course the hardwood and softwood plywoods. Each of these products are designed to fill a need in industry.

Plywood is a type of made from thin sheets of , called plies or . The layers are glued together so that adjacent plies have their grain at right angles to each other for greater strength.