Glossary

Adhesive—A substance capable of holding materials together by surface attachment. It is a general term and includes cements, mucilage, and paste, as well as glue.

Air-Dried—(See Seasoning.)

American Lumber Standards —American lumber standards embody provisions for softwood lumber dealing with recognized classifications, nomenclature, basic grades, sizes, description, measurements, tally, shipping, provisions, grademarking, and inspection of lumber. The primary purpose of these standards is to serve as a guide in the preparation or revision of the grading rules of the various lumber manufacturers' associations. A purchaser must, however, make use of association rules because the basic standards are not in themselves commercial rules.

Angiosperms—Various  orders of hardwoods that have true flowers and seeds enclosed in a fruit.

Anisotropic—Exhibiting different properties when measured along different axes. In general, fibrous materials such as wood are anisotropic.

Annual Growth Ring—The layer of wood growth put on a tree during a single growing season. In the temperate zone the annual growth rings of many species (e.g., oaks and pines) are readily distinguished because of differences in the cells formed during the early and late parts of the season. In some temperate zone species (black gum and sweetgum) and many tropical species, annual growth rings are not easily recognized.

Bleaching, pulp—The process of removing residual lignin from pulp to improve the brightness and strength.

Board—(See Lumber.)

Board Foot—A unit of measurement of lumber represented by a board 1 foot long, 12 inches wide, and 1 inch thick or its cubic equivalent. In practice, the board foot calculation for lumber 1 inch or more in thickness is based on its nominal thickness and width and the actual length. Lumber with a nominal thickness of less than 1 inch is calculated as 1 inch.

Bole—The main stem or trunk of a tree of substantial diameter—roughly, capable of yielding sawtimber, veneer logs, or large poles, Seedlings, saplings, and small-diameter trees have stems, not boles.

Bolt—(1) A short section of a tree trunk; (2) in veneer production, a short log of a length suitable for peeling in a lathe.

Bond—(noun). The union of materials by adhesives.

Bond—(verb). To unite materials by means of an adhesive.

Bucking—Cross-cutting felled trees into logs or bolts.

Built-Up Timbers—An assembly made by joining layers of lumber together with mechanical fastenings so that the grain of all laminations is essentially parallel.

Calorific value—The potential heat-production value of a wood source. Depends on the cellulos-lignin ratio, the percentage of extractives, and the moisture content.

Cellulose—The carbohydrate that is the principal constituent of wood and forms the framework of the wood cells.

Chipper Canter—A headrig machine that reduces barked logs directly to chips and cants without producing sawdust.

Circular saw—A circular metal plate with teeth on the circumference that rotates on a drive shaft.

Close-Grained Wood—(See Grain.)

Coarse-Grained Wood—(See Grain.)

Cold- Pressed Plywood—(See Plywood.)

Composites—Built-up, bonded products consisting wholly of natural wood, or in combination with metals,
plastics, etc.

Compression Wood—Abnormal wood formed on the lower side of branches and inclined trunks of softwood trees. Compression wood is identified by its relatively wide annual rings (usually eccentric when viewed on cross section of branch or trunk), relatively large amount of summerwood, sometimes more than 50 percent of the width of the annual rings in which it occurs, and its lack of demarcation between earlywood and latewood in the same annual rings. Compression wood shrinks excessively lengthwise, as compared with normal wood.

Conifer—(See Softwoods or Gymnosperms.)

Cross-Grained Wood—(See Grain.)

Curly-Grained Wood—(See Grain.)

Deciduous—(See Hardwoods or Angiosperms.)

Density—As usually applied to wood of normal cellular form, density if the mass of wood substance enclosed within the boundary surfaces of a wood-plus-voids complex having unit volume. It is variously expressed as pounds per cubic foot, kilograms per cubic meter, or grams per cubic centimeter at a specified moisture content.

Diagonal-Grained Wood—(See Grain.)

Dimension—(See Lumber.)

Dressed Size—(See Lumber.)

Dry Kiln—(See Kiln.)

Earlywood—The portion of the annual growth ring that is formed during the early part of the growing season. It is usually less dense and weaker mechanically than latewood. Also called springwood.

Edge-Grained Lumber—(See Grain.)

Encased Knot—(See Knot.)

End-Grained Wood—(See Grain.)

Equilibrium Moisture Content—The moisture content at which wood neither gains nor loses moisture when surrounded by air at a given relative humidity and temperature.

Exterior Plywood—(See Plywood.)

Extractive—Substances in wood, not an integral part of the cellular structure, that can be removed by solution in hot or cold water, ether, benzene, or other solvents that do not react chemically with wood components.

Extruded Particleboard—(See Particleboard.)

Factory and Shop Lumber—(See Lumber.)

Fiberboard—A broad generic term inclusive of sheet materials of widely varying densities manufactured of refined or partially refined wood (or other vegetable) fibers. Bonding agents and other materials may be added to increase strength, resistance to moisture, fire, or decay, or to improve some other property. (See Medium-Density Fiberboard.)

Fiber Saturation Point—The stage in the drying or wetting of wood at which the cell walls are saturated and the cell cavities free from water. It applies to an individual cell or group of cells, not to whole boards. It is usually taken as approximately 30 percent moisture content, based on ovendry weight.

Fiddleback-Grained Wood—(See Grain.)

Fine-Grained Wood—(See Grain.)

Flakeboard—(See Particleboard.)

Flat-Grained Wood—(See Grain.)

Flitch—A portion of a log sawn on two or more faces—commonly on opposite faces leaving two waney edges. When intended for resawing into lumber, it is resawn parallel to its original wide faces. Or, it may be sliced or sawn into veneer, in which case the resulting sheets of veneer laid together in the sequence of cutting are called a flitch. The term is loosely used.

Furnish—The wood material which has been reduced for incorporation into wood-based fiber or particle panel products.

Glue Laminating—Production of structural or nonstructural wood members by bonding two or more layers of wood together with adhesive.

Glue—Originally, a hard gelatin obtained from  hides, tendons, cartilage, bones, etc., of animals. Also, an adhesive prepared from this substance by heating with water. Through general use the term is now synonymous with the term "Adhesive."

Grade—The designation of the quality of a manufactured piece of wood or of logs.

Grain—The direction, size, arrangement, appearance, or quality of the fibers in wood or lumber. To have a specific meaning the term must be qualified.

Green.—Freshly sawed or undried wood. Wood that has become completely wet after immersion in water would not be considered green, but may be said to be in the "green condition."

Growth Ring—(See Annual Growth Ring.)

Gymnosperm—A term signifying plants bearing exposed seeds, usually borne in cones. See also softwoods.

Hardboard—A generic term for a panel manufactured primarily from interfelted ligno-cellulosic fibers (usually wood), consolidated under heat and pressure in a hot press to a density of 31 pounds per cubic foot or greater, and to which other materials may have been added during manufacture to improve certain properties.

Hardwoods—Generally one of the botanical groups of trees that have broad leaves in contrast to the conifers or softwoods. The term has no reference to the actual hardness of the wood. (Also called Angiosperms/
deciduous.)

Heartwood—The wood extending from the pith to the sapwood, the cells of which no longer participate in the life processes of the tree. Heartwood may contain phenolic compounds, gums, resins, and other materials that usually make it darker and more decay resistant than sapwood.

Hemicellulose—A celluloselike material (in wood) that is easily decomposable as by dilute acid, yielding several different simple sugars.

Holocellulose—The total carbohydrate fraction of wood – that is, cellulose plus hemicellulose.

Horiziontally Laminated Timbers—Laminated timbers designed to resist bending loads applied perpendicular to the wide faces of the laminations.

Insulating Board—(See Structural Insulating Board.)

Intergrown Knot—(See Knot.)

Interior Plywood—(See Plywood.)

Interlocked-Grained Wood—(See Grain.)

Juvenile wood—The innermost layers of wood adjacent to the pith, formed during the juvenile years of the tree's growth. Certain features, such as cell structure and size, differ from those typical of mature wood.

Kiln—A chamber having controlled air-flow, temperature, and relative humidity for drying lumber, veneer, and other wood products.

Kiln Dried—(See Seasoning.)

Knot—That portion of a branch or limb that has been surrounded by subsequent growth of the stem. The shape of the knot as it appears on a cut surface depends on the angle of the cut relative to the long axis of the knot.

Kraft (sulfate) process—A chemical pulping process in which lignin is dissolved by a solution of sodium hydroxide and sodium sulfide.

Kraft pulp—A chemical wood pulp obtained by cooking wood chips at high temperature in a solution of sodium hydroxide and sodium sulfide.

Laminated Timbers—An assembly made by bonding layers of veneer or lumber with an adhesive so that the grain of all laminations is essentially parallel (see Built-Up Timbers).

Laminated Veneer Lumber—(LVL). A structural lumber manufactured from veneers laminated into a panel with the grain of all veneer running parallel to each other. The resulting panel is normally manufactured in 3/4 to 1-1/2 inch thicknesses and ripped to common lumber widths of 1-1/2 to 11-1/2 inches, or wider.

Laminate—A product made by bonding together two or more layers (laminations) of material or materials.

Latewood—The portion of the annual growth ring that is formed after the earlywood formation has ceased. It is usually denser and stronger mechanically than earlywood. Also called summerwood.

Layup—The process of loosely assembling the adhesive-coated components of a unit, particularly a panel, to be pressed or clamped.

Lignin—The second most abundant constituent of wood, located principally in the secondary wall and the middle lamella, which is the thin cementing layer between wood cells. Chemically it is an irregular polymer of substituted propylphenol groups, and thus no simple chemical formula can be written for it.

Longitudinal—Generally, parallel to the direction of the wood fibers.

Loose Knot—(See Knot.)

Lumber—The product of the saw and planing mill not further manufactured than by sawing, resawing, passing lengthwise through a standard planing machine, crosscutting to length, and matching.

Marine Plywood—(See Plywood.)

Mat-Formed Particleboard—(See Particleboard.)

Matched Lumber—(See Lumber.)

Mechanical pulping—The production of fibers and fiber bundles by grinding wood with pulpstones or by mechanical refiners as opposed to chemical methods.

Medium-Density Fiberboard—A panel product manufactured from lignocellulosic fibers combined with a synthetic resin or other suitable binder. The panels are manufactured to a density of 31 pcf (0.50 specific gravity) to 55 pcf (0.88 specific gravity) by the application of heat and pressure by a process in which the interfiber bond is substantially created by the added binder. Other materials may have been added during manufacturing to improve certain properties.

Mende-Process Board—(See Particleboard.)

Moisture Content—The amount of water contained in the wood, either expressed as a percentage of the weight of the ovendry wood or as a percentage of total weight of a piece.

Molded Plywood—(See Plywood.)

Multilayer Particleboard—(See Particleboard.)

Nominal-Size Lumber—(See Lumber.)

Open-Grained Wood—(See Grain.)

Oriented Strand Board—(See Particleboard.)

Ovendry Wood—Wood dried to a relatively constant weight in a ventilated oven at 102 to 105˚C.

Paperboard—A general term describing sheets made of fibrous material 0.012 in. or more in thickness. Compared with paper, paperboard is heavier per unit area, thicker, and more rigid. Paperboard is the term used to describe any single variety, or group of varieties, of board materials used in the production of boxes, folding cartons, and solid fiber and corrugated shipping containers.

Paper—Generally, a matted or felted sheet of vegetable fiber, formed on a screen from a water suspension, used for writing and printing as well as for wrapping and many other purposes. Paper is one of two broad subdivisions of the general term, papers; the other is paperboard.

Particleboard—A generic term for a material manufactured from wood particles or other ligno-cellulosic material and a synthetic resin or other suitable binder.

Particles—The aggregate component of particleboard manufactured by mechanical means from wood. These include all small subdivisions of wood such as chips, curls, flakes, sawdust, shavings, silvers, strands, wafers, wood flour, and wood wool.

Patterned Lumber—(See Lumber.)

Peel—To convert a log into veneer by rotary cutting.

Pile—A long, heavy timber, round or square, that is driven deep into the ground to provide a secure foundation for structures built on soft, wet, or submerged sites; e.g., landing stages, bridge abutments.

Pin Knot—(See Knot.)

Plainsawed Lumber—(See Grain.)

Plywood—A glued wood panel made up of relatively thin layers of veneer with the grain of adjacent layers at right angles, or of veneer in combination with a core of lumber or of reconstituted wood. (See Composites.) The usual constructions have an odd number of layers.

Postformed Plywood—(See Plywood.)

Preservative—Any substance that, for a reasonable length of time, is effective in preventing the development and action of wood-rotting fungi, borers of various kinds, and harmful insects that deteriorate wood.

Quartersawed Lumber—(See Grain.)

Radial—Coincident with a radius from the axis of the tree or log to the circumference. A radial section is a lengthwise section in a plane that passes through the center line of the tree stem.

Reaction Wood—Wood with more or less distinctive anatomical characters, formed typically in parts of leaning or crooked stems and in branches. In hardwoods this consists of tension wood and in softwoods of compression wood.

Relative Density—Formerly called specific gravity. As applied to wood, the ratio of the oven-dry weight of a sample to the weight of a volume of water equal to the volume of the sample at a specified moisture content (green, air-dry, or oven-dry).

Relative Humidity—Ratio of the amount of water vapor present in the air to that which the air would hold at saturation at the same temperature. It is usually considereed on the basis of the weight of the vapor but, for accuracy, should be considered on the basis of vapor pressures.

Rotary-Cut Veneer—(See Veneer.)

Rough Lumber—(See Lumber.)

Sapwood— The wood of pale color near the outside of the log. Under most conditions the sapwood is more susceptible to decay than heartwood.

Saw Kerf—(1) Grooves or notches made in cutting with a saw; (2) that portion of a log, timber, or other piece of wood removed by the saw as sawdust in parting the material into two pieces.

Sawed Veneer—(See Veneer.)

Seasoning—Removing moisture from green wood to improve its serviceability.

Semichemical pulp—Pulp obtained by mild treatment of wood chips by any of the chemical pulping processes, which remove only part of the lignin from the wood chips, followed by mechanical treatment to complete the separation of individual cellulose fibers.

Shakes—In construction, a type of shingle usually hand cleft from a bolt and used for roofing or weatherboarding.

Shaving—A small wood particle of indefinite dimensions developed incidental to certain woodworking operations involving rotary cutterheads usually turning in the direction of the grain. This cutting action produces a thin chip of varying thickness, usually feathered along at least one edge and thick at another and generally curled.

Sheathing—The structural covering, usually of boards, building fiberboards, or plywood, placed over exterior studding or rafters of a structure.

Shingles—Thin, rectangular pieces of wood, sawn along the grain and tapering in thickness, used like tiles for roofing and weatherboarding.

Shiplapped Lumber—(See Lumber.)

Shipping-Dry Lumber—(See Lumber.)

Shop Lumber—(See Lumber.)

Shrinkage—Contraction caused by drying wood below the fiber saturation point; it is greater in the wide face of flat-grain than in edge-grain lumber, and minimal in the longitudinal direction.

Side Lumber—(See Lumber.)

Side-Grained Wood—(See Grain.)

Siding—The finish covering of the outside wall of a frame building, whether made of horizontal weatherboards, vertical boards with battens, shingles, or other material.

Slab—The exterior portion of a log removed in sawing lumber.

Slash-Grained Wood—(See Grain.)

Sliced Veneer—(See Veneer.)

Softwoods—Generally, one of the botanical groups of trees that in most cases have needlelike or scalelike leaves, the conifers, also the wood produced by such trees.  The term has no reference to the actual hardness of the wood. (See Gymnosperm.)

Sound Knot—(See Knot.)

Specific Gravity—(See Relative Density.)

Specific heat—The heat in joules required to raise the temperature of one gram of wood 1˚C.

Spike Knot—(See Knot.)

Spiral Grain—(See Grain.)

Spiral-Grained Wood—(See Grain.)

Springwood—See earlywood.

Stem—The principal axis of a tree, capable of producing sawlogs, veneer logs, large poles, or pulpwood.

Straight Grained—(See Grain.)

Straight-Grained Wood—(See Grain.)

Structural Insulating Board—A generic term for a homogeneous panel made from lignocellulosic fibers (usually wood or cane) characterized by an integral bond produced by interfelting of the fibers, to which other materials may have been added during manufacture to improve certain properties, but which has not been consolidated under heat and pressure as a separate stage in manufacture, said board having a density of less than 31 pcf (specific gravity 0.50) but having a density of more than 10 pcf (specific gravity 0.16).

Structural Lumber—(See Lumber.)

Structural Timbers—Pieces of wood of relatively large size, the strength or stiffness of which is the controlling element in their selection and use. Examples of structural timbers are trestle timbers (stringers, caps, posts, sills, bracing, bridge ties, guardrails); car timbers (car framing, including upper framing, car sills); framing for building (posts, sills, girders); ship timber (ship timbers, ship decking); and crossarms for poles.

Sulfate process—See kraft (sulfate) process.

Sulfite process—A chemical pulping process in which wood is cooked in aqueous acid sulfite solution containing free sulfur dioxide.

Sulfite pulp—A chemical wood pulp obtained by cooking wood chips in a bisulfite–sulfurous acid solution.

Summerwood—See latewood.

Surfaced Lumber—(See Lumber.)

Tangential—Strictly, coincident with a tangent at the circumference of a tree or log, or parallel to such a tangent. In practice, however, it often means roughly coincident with an annual layer. A tangential section is a longitudinal section through a tree or limb perpendicular to a radius. Flat-grain lumber is sawn tangentially.

Tension Wood—Abnormal wood found in leaning trees of some hardwood species and characterized by the presence of gelatinous fibers and excessive longitudinal shrinkage. Tension wood fibers hold together tenaciously, so that sawed surfaces usually have projecting fibers, and planed surfaces often are torn or have raised grain. Tension wood may cause warping.

Timber, Standing—Timber still on the stump.

Timbers, Round—Timbers used in the original round form, such as poles, piling, posts, and mine timbers.

Timbers—(See Lumber.)

Veneer—A thin layer or sheet of wood.

Sliced Veneer—Veneer that is sliced off a log, bolt, or flitch with a knife.

Vertical-Grained Lumber—(See Grain.)

Vertically Laminated Timbers—Laminated timbers designed to resist bending loads applied parallel to the wide faces of the laminations.

Waferboard—(See Particleboard.)

Wavy-Grained Wood—Wood in which the fibers collectively take the form of waves or undulations.

Yard Lumber—(See Lumber.)