Plywood does not grow on trees --- at least, not in its final form. It is an engineered wood made from veneers of various types of softwood and hardwood or combinations of the two. Plywood is a very common building material in modern construction. It also has a variety of other uses.
Description of Plywood
Plywood is engineered from three or more thin layers of wood, or veneers, laminated together with adhesives. The types of wood and the particular adhesives depend on the kind of plywood being manufactured and the uses to which it will be put. However, Douglas fir is the most widely used softwood in plywood manufacture. As a building material, it is stronger than most softwoods and hardwoods, and much less expensive.
History of Plywood
Laminated woods have been found in the tombs of the ancient Egyptian pharaohs dating back to about 1500 B.C. A thousand years ago, the Chinese shaved wood and glued the pieces together to use in making furniture. In the 17th and 18th centuries, a type of plywood was used by English, French and Russian builders. Construction-grade plywood was used in Portland, Oregon, in building projects for the World's Fair of 1905. During World War II, plywood was a basic construction material for barracks, PT boats, gliders, and lifeboats, and after the war it supported the economic boom of the 1950s and early 1960s.
How Plywood Is Manufactured
Plywood is generally made from trees planted for that specific purpose by a plywood company. After the tree has been cut down, the logs are debarked and cut into 8-foot, 4-inch-long sections to make standard 8-foot-long plywood sheets. These logs are called peeler blocks. Workers heat and soak the peeler blocks and then transport them to a peeler lathe. The lathe rotates the peeler block only on its long axis, and an 8-foot-long blade peels a continuous thin sheet of wood --- veneer --- from the block. The veneer is then cut into 4-foot, 6-inch widths and allowed to dry. Three or more veneers are laid down with a layer of glue between the sheets. The sheet of plywood then goes through a hot press, which completes the lamination process by subjecting the sheets to heat and pressure. Plywood is manufactured and graded according to its strength, whether it is for interior or exterior use and how clear the surface is of blemishes and knots.
Uses of Plywood
Plywood has many uses --- furniture and cabinet making; frames, walls and roofs of buildings; shuttering concrete forms for pouring concrete for foundations, buildings and other uses; flooring; shipping containers; vehicle floors; decking; pallets; boxes; signs; fences; boat manufacture; and musical instruments, to name just a few.
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