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term for timber that has been cut into boards for use as a building material. The major steps in producing lumber involve logging (the felling and preparation of timber for shipment to sawmills), sawing the logs into boards, grading the boards according to defects and
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botanically, the xylem tissue that forms the bulk of the stem of a woody plant. Xylem conducts sap upward from the roots to the leaves, stores food in the form of complex carbohydrates, and provides support; it is made up of various types of cells specialized for each of
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(wood grades), material obtained from trees that retains its natural physical structure and chemical composition. Timber may be rough or processed.
Rough timber is a product of the logging industry. It is obtained from sawn trees after the branches have been removed and the trunks crosscut into pieces of the required length. Since its cross section resembles a circle, the wood is called round timber. Round timber is used whole (after the bark has been stripped away) in the construction of industrial and residential buildings, as supports and poles for telephone and electrical transmission lines, as props in underground work (for example, mining), and as fences (pickets, rods). Round timber is the raw material for the sawing, plywood, match, packaging, paper-and-pulp, and wood-chemical industries.
The materials fashioned from round timber that retain their natural structure are classified as processed timber. Produced by the sawing and woodworking industries, they include lumber (beams, rods, crossties, boat and deck planks, and soundboards for musical instruments), split timber (parquet flooring and staves for barrels), and planed and hulled veneer.
Quality standards for timber are based on the intended purpose of the grades, the species of trees from which they are to be made, the dimensions of the grades and their division into varieties, and the limits of allowable flaws in the timber and of defects caused by processing.
Round timber is generally divided into softwoods and hardwoods without differentiation by species, which is specified only in rare cases—for example, soundboards are made only from spruce, and staves for wine casks only from oak. The length and thickness of timber vary considerably. The minimum dimensions are usually indicated for round timber; there are no maximum limits. Timber quality is determined by external appearance and, in the case of particularly important grades, by testing.
REFERENCESLapirov-Skoblo, S. Ia. Lesnoe tovarovedenie, 3rd ed. Moscow, 1968.
Lesomaterialy kruglye: Sbornik standartov. Moscow, 1969.
P. P. AKSENOV