Bristol Stair and Joinery Co. has a huge selection of Stairs, Stair Parts, Spirals Doors, Windows, Skirting, Architecture, Dado & Picture Rails, all at exceptional prices. We provide a full design and fitting service. Wood, natural composite material that forms the trunks of trees, and that has been used for thousands of years as a fuel and as a material of building construction. Technically, the term wood includes similar materials in other parts of the plant, including even the so-called veins in leaves, but only those portions of wood which have commercial importance are discussed in this article.Bristol Stair & Joinery Co. joiners in bristol,joiner, traditional joinery,wood turning,stair newels, staircase makers, stair spindles, staircase balustrades, specialist joiners, staircase handrails, stair base rails, stair spirals, stair parts, dado railsarchitecture,stair part,spirals,door,garage door french door back door entry door exterior door patio door interior door window and door front door entrance door custom door dado rails,handrails stair handrails wood deck handrails product turning wood turning supply
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For the botanical aspects of wood, including its structure and growth, see Tree; Xylem. For growth and distribution, see Forest. For the cultivation of trees for wood, see Forest Conservation and Management. For the cutting of trees and the manufacture of timber, see Timber Industry. II. Grain and StructurePrint section The typical markings, called grain, that are found on all types of natural wood are due to the structure of the wood. Wood consists essentially of fine cellular ducts or tubes, which carry water and dissolved minerals from the roots to the leaves, and which are thus arranged more or less vertically within the trunk. When the wood is cut parallel to the axis of the trunk, straight-grained timber is usually produced. In some trees, however, the ducts are helical; that is, they twist around the trunk as they ascend. Such trees produce cross-grained timber, which is also obtained from ordinary trees when the cut is not parallel to the axis of the trunk. Many woods have prominent annual rings. The trunk of a tree does not grow in length, except at its tip, but does grow in width. The only portion of the trunk that is engaged in active growth is the cambium, a thin layer entirely surrounding the trunk. In trees of the Temperate Zone, the cambium lays down new wood during the spring and summer, and in most trees the early wood is more porous and therefore lighter in colour than the wood produced later in the season. The trunk of a tree is thus surrounded each year by a new pair of concentric sheaths, one darker than the other. Although the thin layer of cambium is the only part of the trunk that is alive in the sense that it is engaged in active growth, living cells are also interspersed among the xylem cells of the sapwood. As the tree grows older, however, the central portion of the trunk dies completely; the ducts become plugged with gums or resins, or merely air. This central part of the trunk is called heartwood. The internal changes are accompanied by changes in colour typical of the species of trees, so that the heartwood is usually darker than the sapwood.
