Wood Grain

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Wood Grain

 

the natural pattern of a section of wood, showing the particular features of the wood’s anatomical structure. The diversity of grains among species is due to the specific features of the macrostructure and microstructure of the wood and depends on the representativeness, dimensions, and interpositioning of the wood’s basic anatomical elements—vessels, medullary rays, and wood fibers. The grain largely determines the decorative value of the wood in cabinetwork and serves as an important feature in the identification of tree species.

In comparison with hardwoods, softwoods usually have a simpler grain. Species in which the anatomical elements are not easily distinguishable by the naked eye have a weak grain (birch, pear, and box). Species with clearly visible, broad vessels in longitudinal sections have a striated grain. If the longitudinal striae are collected into broad strips (oak, Amur cork, and ash), the grain is said to be band-striated. Some grains may have a random arrangement of striae (English walnut, eucalyptus, and the genus Diospyros).

Wood with clearly delineated medullary rays (beech, oak, and plane) is characterized in radial sections by a grain in which the rays are seen as shiny, broken strips or spots and in tangential sections by rays that appear as elongated, tapered dashes, usually darker than the surrounding wood. The former type of grain is more highly valued for decorative purposes than the latter, and planed, radially cut veneer sheets are preferred to peeled, tangentially cut sheets for facing. In certain instances the decorative qualities of the wood grain are enhanced by flaws (seeBURL).

Several different techniques are used to heighten the natural grain of wood: cutting at an angle to the longitudinal axis of the tree trunk, which produces a characteristic pyramidal grain; planing and peeling with a knife with a scalloped blade and subsequent smoothing of the veneer sheet; conical stripping; and uneven pressing. A transparent wood finish heightens the texture and increases its decorative effect.

REFERENCES

See references under WOOD.

I. K. CHERKASOV