The tough, fibrous cellular substance that makes up most of the stems and branches of trees beneath

the bark.

WOOD

• Tongue and groove

A method of fitting similar objects together, edge to edge, used mainly with wood, in flooring, parquetry, panelling, and similar constructions. Tongue and groove joints allow two flat pieces to be joined strongly together to make a single flat surface. Before plywood became common, tongue and groove boards were also used for sheathing buildings and to construct concrete formwork.

• click system

A method of joining boards together without the use of glue. The tongue is made with a protrusion that fits over a corresponding rebate in the groove.

WOOD INSTALLATION

• plywood

A wood panel product made by bonding veneers together under heat and pressure, usually with the grain at right angles to each other and symmetrical about the center ply.

WOOD FABRICATION

• group numberA number identifying one of five groups of species used for the face and back veneers of a plywood panel, the species being classified on the basis of bending strength and stiffness, with Group 1 containing the stiffest species and Group 5 the least stiff.

• exterior plywoodA plywood panel consisting of C-grade veneers or better, bonded with a fully waterproof glueline for permanent exposure to weather or moisture

• interior plywoodA plywood panel made with D-grade veneers or better, bonded with an exterior, intermediate, or interior glueline.

VENEER GRADE

A grade defining the appearance of a veneer in terms of growth characteristics and the number and size of repairs that may be made during manufacture.

• N-gradeA smooth softwood veneer of all heartwood or all sapwood, free from open defects with only a few well-matched repairs.

• A-gradeA smooth, paintable softwood veneer with a limited number of neatly made repairs parallel to the grain.• B-gradeA softwood veneer having a solid surface with circular repair plugs, tight knots, and minor splits permitted.• C-gradeA softwood veneer having tight knots and knotholes of limited size, synthetic or wood repairs, and discoloration and sanding defects that do not impair the strength of the panel.• C-plugged gradeAn improved C-grade softwood veneer having smaller knots and knotholes, some broken grain, and synthetic repairs.• D-gradeA softwood veneer having large knots and knotholes, pitch pockets, and tapering splits.

• decorative plywoodHardwood-faced plywood manufactured for use as paneling or in cabinetry and furniture.• veneerA thin sheet of wood rotary cut, sliced, or sawn from a log or flitch and used as a superior facing to inferior wood or bonded together to form plywood.

• crossbandA layer of veneer immediately adjacent to and at right angles to the face plies in a plywood panel.

• coreThe center of a plywood panel, consisting of veneers, saw lumber, or composition board.

• bandingThe solid wood stock extending around the sides of a veneered panel, concealing the core and facilitating the shaping of the panel edges.

• matchingArranging sheets of veneers so as to emphasize the color and figure of the wood.• book matching

Arranging veneers from the same flitch alternately face up and face down to produce symmetrical mirror images about the joints between adjacent sheets.

• herringbone matchingBook matching in which the figures in adjacent sheets slope in opposite directions.

• slip matchingArranging adjacent sheets of veneer from the same flitch side by side without turning so as to repeat the figure.

• diamond matchingArranging four diagonally cut sheets of a veneer to form a diamond pattern about a center.

• random matchingArranging veneers to intentionally create a casual, unmatched appearance.

• figureThe natural pattern on a

sawed wood surface produced by the

intersection of annual rings, knots, burls, rays,

and other growth characteristics.

• treated wood

Wood that has been coated or impregnated with chemicals to improve its resistance to decay, insect infestation, or fire.

• pressure-treated wood

Wood impregnated with chemicals applied under pressure to reduce its resistance to decay and insect infestation.

• non-pressure-treated wood

Wood coated, dipped, or impregnated with a preservative under atmospheric pressure.

• Fire-retardant wood

Wood treated with minerals salts impregnated under pressure to reduce flammability or combustibility. The salts react chemically at temperatures below the ignition point of the wood to break down into water and carbon dioxide.

WOOD MAINTENANCE METHODS AND TECHNIQUES

• full-cell process

A process for pressure-treating wood in which a vacuum is first drawn to remove air from the wood firers and allow the preservative to be absorbed by the cell walls, after which pressure Is applied to force additional preservative into the cell cavities. The full-cell process leaves the maximum amount of preservative in the wood.

• empty-cell process

A process for pressure-treating wood in which the pressure of the entering preservative entraps air in the wood fibers, which expands when the pressure is released to expel excess preservative from the cell cavities. The empty-cell process yields a drier product while ensuring deep, uniform penetration of the preservative.

• vacuum process

A non-pressure treatment in which a vacuum or partial vacuum exhausts air from the cells and pores of the wood while atmospheric pressure forces preservative into the wood.

WOOD MAINTENANCE METHODS AND TECHNIQUES

CONT.

• preservativeAny various substances for coating or impregnating wood in order to protect it against wood-destroying fungi and insects

• water-borne preservativeAn inorganic, water-soluble compound, as ammoniacal copper arsenite (CCA), used as a wood preservative. ACA and CCA affix chemically to the wood cell walls and is resistant to leaching. The copper acts as a fungicide while the arsenate is toxic to wood-destroying insects. Wood treated with ACA and CCA is odorless and paintable.• oil-borne preservativeAn organic chemical dissolved in a petroleum oil carrier, such as pentachlorophenol or copper naphthenate,used as a wood preservative. Pentachlorophenol, the most commonly used oil-borne preservative, has a persistent odor, is Insoluble in water, and is highly toxic not only to fungi and insects but also to humans and plants. • creosoteAn oily liquid of aromatic hydrocarbons obtained by distillation of cool tar, used as a wood preservative for marine installations or odor severe exposures to wood-destroying fungi and insects. Creosote and creosote solutions have a penetrating odor and render wood unpaintable.