Glossary of Terms

Backs: The reverse side to the face of a plywood panel. Typically, backs are of a lower grade of veneer than the face on plywood panels that call for a face and a back.

Bark Pocket: A small area of bark surrounded by a newer growth of normal wood.

Burl: A swirl or twist in the grain of wood. It usually occurs near a knot, but does not contain a knot itself.

Core: (Sometimes called a center.) The innermost portion of plywood. While usually made up of a softwood veneer, a core may be constructed using fiberboard, particleboard, or lumber.

Crossbar: An imperfection or irregularity in the grain of wood that runs at right angles to the lengthwise grain.

Crossbanding: An inner ply of veneer placed at right angles to the core, face and back of a plywood panel.

Defects: Loose knots, splits, voids, wormholes, bark pockets, and other flaws that interrupt the smooth flow of a wood surface.

Delamination: The separation of the inner plys in a panel. This is typically caused by the failure of the adhesive bond.

Face: The best side of a plywood panel on which the outer veneers are of different grades. (See “Backs.”)

Grain: The pattern, size, and direction of the fibers in wood or veneer.

Gum Spots: Accumulation of resinous material that can occur on panel surfaces of certain species. May be removed by sanding.

Half-Round Slicing: Off-center slicing cut slightly across the annular grown rings. This creates half-round, plain-sliced, or rotary characteristics.

Heartwood: The center portion of a tree. It is made up of mature wood that has stopped growing. Its darker color usually makes it distinguishable from sapwood, the growing, outer portion.

Knot: The circular portion of a board or veneer that was once the base of a branch or twig growing from the trunk of a tree.

Knot (Open): Opening produced when a portion of a knot has dropped out or separated during the seasoning process.

Knot (Pin): Sound knots less than ¼” in diameter.

Knot (Sound): Knots that are solidly fixed by growth and retain their place in lumber or veneer.

Knothole: Opening produced when knots drop from the wood in which they were once embedded.

Lap: A flaw caused by the accidental overlapping of one piece of veneer onto another in the same layer of ply.

Medium Density Fiberboard (MDF): A panel or core material manufactured using pressure-cooked wood fiber, resin, and wax.

Mineral Streak: A discoloration of hardwood and hardwood veneer.

Particleboard: A panel or core material manufactured from pressed sawmill shavings, resin, and wax.

Patches: Filler material inserted into defects of veneers or panels, then sanded during repair process.

Plain Sliced: Veneer sliced tangential to the tree’s annual rings.

Ply: A single sheet of veneer that forms one layer of a multi-layered piece of plywood.

Plywood, Hardwood: A panel composed of layers of inner plys, or other core material joined with an adhesive to a face veneer of hardwood and a back veneer, usually also composed of hardwood.

Quarter Slicing: Quartered log sliced at right angles to the growth rings.

Rift Cut: Veneer cut from a quartered log on a 90 degree angle to the grain.

Rotary Cut: Veneer peeled from a whole log set in a lathe and turned against a special knife.

Sapwood: The light colored, living portion of a tree located between the heartwood and the bark.

Slip Matched: Veneer sheets that are laid side by side to form a whole sheet with a respective grain appearance.

Splits: Separations of the wood fiber that run parallel to the grain.

Veneer: Peeled or sliced thin sheets of wood used as inner plys or as decorative faces.

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