Glossary
Click a letter to jump to that section This glossary was derived from various sources and represents generally accepted usage of terms in the forest products industry. |
Actual Yield: The actual amount that is produced.
Adhesive: A substance that causes materials to stick to each other through surface attachment.
Air Dried: Dried by exposure to air in a yard or shed, without artificial heat.
Air Reversal: Changing the airflow to flow in the opposite direction through a load of drying lumber or products.
Allowable Unit Stress: The value of a strength property normally published for design use. Allowable unit stresses are identified with grade descriptions and standards, reflect the anisotropic structure of wood, and anticipate certain end uses.
Anemometer: an instrument for measuring air velocity.
Anisotropic: Not isotropic; that is, not having the same properties in all directions.
Annual Layers (rings): The layers of wood grown by a tree during a single growing season; in the temperate zone, annual layers of many species are readily distinguished because of differences in the cells formed during the early and late parts of the season
Armoire: A large cupboard, for storing clothes. Probably an adaptation of the aumbry, or ambry, used in early English times for the storing of arms and armor.
Assembly Time: The minimum and maximum time allowed after glue spreading before pressure must be applied to form a satisfactory wood-glue bond.
Baffle: In forced air or kiln drying, a canvas, metal, or wood barrier used for deflecting, checking, or otherwise directing the flow of air.
Balloon Frame System: A framing system, principally used for two-story housing, in which the studs run the NH height of the building from the foundation wall to the top plate supporting the roof. Floor joists of the upper story rest on a sill nailed to the studs.
Bandsaw: A band of steel with teeth on one edge (single cutting) or both edges (double cutting), running on a set of large wheels. Used for longitudinal cutting of wood. See also twin and quad bandsaws.
Barker or Debarker: A machine for removing bark either mechanically or by high-pressure water jets.
Bark Pockets: Small patches of bark that have become partially or wholly enclosed by the growth of a tree.
Barrier or Base Coat: An initial coating applied to protect plastics from being attacked by the solvents in subplastics from being attacked by the solvents in subsequently applied finishing materials. Also called base coat.
Beam: A structural member that supports a load applied transversely to it. See also timbers, rectangular.
Bent Wood: Curved wood formed by steaming or boiling, or by special finishing, and then bending to a form.
Bevel Angle: The angle of the knife face in relation to the lathe knife.
Bill Out Tickets: Tickets used in production systems to provide count and information control.
Birds-Eye Figure: Figure produced on flat-sawn or rotary-cut surfaces by small, conical depressions of the fibers, which form numerous rounded areas of the grain remotely resembling small eyes. Generally limited to hard maples.
Bleed-Through: The exudation of colored wood extractives or of coating materials through a paint film.
Blister Spot: or area where veneer does not adhere and bulges like a blister. (In Veneer & Plywood terms) Produced by rotary or half-round cutting through uneven contour of annual rings to give the effect of blisters.
Blistering: The formation of bubbles or pimples on the surface of finished work. Caused by exposure to excessive heat, by grease or other volatile material under the finish, by moisture in the wood or by the too frequent application of coats. Anything which causes a gas or vapor to form under the film may cause blistering.
Blooming: The formation of crystals on the surface of treated wood by exudation and evaporation of the solvent in preservative solutions.
Blue Stain: A bluish or grayish discoloration of the sapwood caused by the growth of certain dark-colored fungi on the surface and in the interior of the wood, made possible by the same conditions that favor the growth of other fungi.
Board Lumber: that is less than 38 mm (2 in.) thick and wider than 38 mm (2 in.).
Board Foot: A standard unit of measurement for logs, usually expressed in multiples of a thousand (MBM). Represents the equivalent number of 1-foot-wide, 1-foot-long, and 1-inch-thick units that can be sawn from a log.
Bolt: A short section of wood, as cut for shingles, shakes, rough dimension stock, stakes, pallet and crating material, and rotary-cut veneer.
Bound Water: Water contained within the cell walls of wood and held by hygroscopic forces.
Bow The distortion of lumber along the face of a piece from end to end, measured at the point of greatest deviation from a straight line.
Boxed Heart The term used when the pith falls entirely within the outer faces of a piece of wood anywhere in its length. Also called boxed pith.
Box Shook Veneer cut primarily for use as box sides, bottoms, and other box parts.
Brash Wood Wood with low resistance to shock and with a tendency to sudden and complete breakage across the grain without splintering.
Brown Rot A condition caused by fungi that decompose the cellulose and associated carbohydrates in wood rather than the lignin. The result is a brown, friable residue. Sometimes called "brown cubical l rot" because of the formation of cracks caused by shrinkage.
Brown Stain See stain.
Buffer Coat A coat of finishing material applied over another dried film to protect it from the solvent action of the succeeding coats.
Bull Edger A combination circular gang resaw and edger used to break down small cants as well as for edging.
Burl Figure Swirled figure produced by cutting through burls, which are hard, woody outgrowths on trees.
Butt Joint An end joint formed by abutting the squared ends of two pieces of wood.
calorific value The potential heat-production value of a wood source. Depends on the cellulose-lignin ratio, the percentage of extractives, and the moisture content.
cambium A thin layer of tissue between the bark and wood that repeatedly subdivides to form new wood and bark cells.
cant A log that has been slabbed on one or more sides by the headrig for subsequent breakdown into lumber by other machines. See also flitch.
canter A machine that produces a cant.
canting A sawing method that is a combination of two other sawing methods, sawing around and live sawing. The most common sawing pattern used for softwoods. See also sawing around and live sawing.
capillary forces The forces of liquid adhesion and cohesion combined with surface tension by which a liquid moves through a cellular structure. Also called `capillary action.'
carbide tipped Machining tools that are surfaced or tipped with a carbide material.
casegoods Finished furniture that serves to store with drawers. i.e. dressers shelves, armoires.
case hardening The condition that occurs when a finishing material dries hard on top and remains more or less soft and mushy underneath instead of drying thoroughly throughout the film. Sometimes caused by relative humidity of the atmosphere being too low. Case hardening may result in checking, cracking and alligatoring when the underneath portion of the film finally becomes hard.
cell A general term for the structural units of plant tissue, including wood fibers, vessel members, and other elements of diverse structure and function.
cellulose The carbohydrate that is the principal constituent of wood and forms the framework of the wood cells.
center Inner layer whose grain direction runs parallel to that of the outer plies.
checks Lengthwise separations of wood that usually extend across the annual layers and commonly result from stresses set up in wood during drying.
chipping The condition which obtains when a dried film of finishing material separates from the underneath surface in the form of flakes or chips. Usually caused by insufficient elasticity or improper adhesion to the base material.
chips Uniform pieces of thin wood, about five eighths of an inch wide and an inch long.
chipper canter A headrig machine that reduces barked logs directly to chips and cants without producing sawdust.
chuck Device used to secure each end of the peeler block to the lathe spindles.
circular saw A circular metal plate with teeth on the circumference that rotates on a drive shaft.
cladding See siding.
clipper, veneer A plywood machine used to cut the veneer ribbons or sheets into specified widths.
CAD Abbreviation for Computer Aided Design. The use of computer hardware and software to assist in designing machine parts, buildings etc.
CNC Abbreviation for "Computer Numerical Control".
cold press A press using time and pressure to assist the adhesive in bonding the panel plies without the aid of externally applied heat.
collapse The flattening of single cells or rows of cells in the heartwood during the drying or pressure treatment of wood. The wood surface is often characterized by a caved-in or corrugated appearance.
composites Built-up, bonded products consisting wholly of natural wood, or in combination with metals, plastics, etc.
composite panel A panel constructed with softwood veneer outerpiles permanently bonded to a reconstituted wood core.
compression failure Deformation of wood fibers resulting from excessive compression along the grain either in direct end compression (as sustained by columns) or in bending (as on the upper side of a beam under load). It may develop in standing trees as a result of bending by wind or snow or internal longitudinal stresses developed in growth; it may also result from stresses imposed after the tree is cut. In surfaced lumber, compression failures may appear as fine wrinkles across the face of the piece.
compression wood Abnormal wood formed on the lower side of branches and inclined stems of softwood trees. Compression wood is identified by its relatively wide annual layers and dark reddish color. Compared with normal wood, it shrinks excessively lengthwise. See also reaction wood.
conditioning The use of humidity in a dry kiln to produce a uniform distribution (equalization) of moisture in timber and to reduce drying stresses.
conifer See softwoods.
cooperage Containers, such as barrels and kegs, consisting of two round head pieces and a body composed of staves held together with hoops.
core In a plywood panel, the crossbanding, the grain direction of which runs perpendicular to that of the outer plies. In a peeler block, the inner portion of the log remaining after the lathe has completed peeling the block.
core board A solid or discontinuous middle layer or ply used in panel-type glued structures (such as furniture panels and solid- or hollow-core doors). In furniture manufacture, also known as `furniture board' or `industrial board.'
core gap Spaces in the cross-bands of plywood in which the veneers do not butt tightly together.
creep The increase in deflection of a beam under load after the passage of time.
crook The distortion of lumber from a straight line along the edges from end to end of a piece, measured at the point of greatest deviation from a straight line.
cross-band In plywood, a layer of veneer whose grain direction is at right angles to that of the face plies; also, to place layers of wood with their grains at right angles in order to minimize shrinking and swelling.
cross cut optimizing Maximizing the efficiency in yield in the cross cut operation.
cross-cutting Sawing wood across the grain to expose an end called a cross-section or transverse section. See also transverse.
cross grain Wood in which the fibers are not aligned parallel to the axis of the piece. See also diagonal grain and spiral grain.
crotch figure Figure produced by the grain when the junction of two or more branches, or the stem and a branch, is cut in a suitable direction
cubical rot See brown rot.
cubic recovery The percentage of the cubic volume of plywood expressed as a percentage of the total cubic volume of log used.
cubic yield The cubic volume of plywood produced expressed as a percentage of the total cubic volume of the log less the peeler core.
culls High-defect peelabel logs that do not meet the requirements of Peeler and Sawmill grade rules but are suitable for rotary cutting.
cunit A unit of measurement which equals 100 cubic metre.
cup A form of board warp in which there is a deviation from a straight line across the width.
cupping Distortion of a board whereby the faces become concave or convex across the grain or width. This condition usually occurs in drying.
cure The change in properties of an adhesive by chemical reaction which results in the development of maximum strength of the adhesive. Generally accomplished by the action of heat or a catalyst, with or without pressure.
curly grain Wavelike undulations in the orientation of wood cells that cause light to be reflected at different angles from the surface and result in a pleasing effect of alternating light and dark bands.
curtain coating A method of glue application in which the veneer passes through a "curtain" of adhesive.
