Hardwood Lumber

Air-dried Lumber

Lumber that has reached its equilibrium moisture content by being exposed to air.

Board Foot

A unit of lumber measure that is 1” thick by 12” wide by 12” long. A board 1” by 6” by 2’ equals 1 board foot. A board 2” by 12” by 12” equals 2 board feet.

Boule

A log live sawn and kept together in the order of sawing.

Bow

A form of warp that is an end-to-end curve along the length of the board.

Burl

A wartlike growth that forms on a tree and that, when sliced, produces extremely disoriented grain patterns that are quite attractive.

Cant

A log that has been debarked and sawn square.

Case-hardening

A drying defect where the surface of wood dries faster than the wetter inner core; this causes permanent set and stresses that release when the board is cut.

Common

(mixed 1 and 2 common) are boards that have too many defects to be FAS or Select.

Conifer

A type of tree that’s characterized by needle-like or scale-like foliage, usually evergreen.

Crook

A form of warp that is an end-to-end curve along the edge of the board.

Crotch

The highly figured wood that occurs where a limb joins a trunk; the grain swirls dramatically where the wood fibers have crowded and twisted together.

Cup

A form of warp that is an edge-to-edge curve across the face of the board.

Deciduous

A type of tree where the leaves fall off every autumn; typically a hardwood, but not always. Some hardwoods in tropical regions keep their leaves all year long.

End Checks

A drying defect caused by the ends of the boards drying faster than the rest of the wood; can usually be prevented by sealing the end grain.

End-coating

The process of sealing the ends of the boards to prevent checking caused by unrestrained evaporation of moisture.

FAS

First and Second. Mixed domestic hardwood lumber grade is the highest grade of hardwood lumber. In most species a board must be 6” or wider, 8’ or longer. Walnut and butternut are the exceptions.

Fiddleback

A type of washboardlike figure that occurs in some species of wood with wavy grain.

Figure

The pattern on a wood’s surface, resulting from the combination of its natural features and the way the log was cut.

Flitch Matched or Book Matched

Sequentially sawn lumber from the same log. 4/4, 5/4, 6/4, etc: Is the thickness given in fractions. It implies that the lumber is rough sawn 1/16”+ over the stated fraction. 4/4 = 1-1/16” to 1-1/8” and should finish to 13/16” 5/4 = 1-5/16” to 1-3/8” and should finish to 1-1/16”

Grade

A designation of the quality of a log or wood product such as lumber, veneer, or plywood.

Grain

The direction of wood fibers in a tree or piece of wood with the respect to the axis of the trunk.

Hardwood

Wood cut from the broad-leaved, mostly deciduous trees that belong to the botanical group Angiospermae.

Heartwood

Mature wood that forms the spine of the tree.

Honeycomb

A drying defect that occurs when the lumber undergoes severe case-hardening in the early stages of drying; appears as deep, internal checks.

Juvenile Wood

The wood in every tree that forms within its first 10 years or so; usually has undesirable characteristics such as low strength and shrinkage along the grain.

Kiln

A heated chamber of a building used to dry lumber; humidity and air circulation are constantly monitored and adjusted as the wood dries.

Kiln-dried Lumber

Lumber that has dried in a kiln to a specific moisture content.

Knot

The section of a branch or limb that has been overgrown by expanding girth of a tree; may be loose or tight.

Moisture Content

The amount of water in a piece of wood expressed as a percentage of the green weight minus the dry weight times 100, divided by the green weight.

Nominal Dimensions

Dimensions based on rough-cut(unplanned) softwoods; a 2x4 is nominally 2” x 4”—It’s actually 1-1/2” x 3-1/2”.

Pith

The small, soft core occurring in the center of the tree trunk.

Plain Sawn

Lumber sawn parallel to the grain.

Quatersawn Lumber

Vertical grained lumber.

Ray

a ribbon-shaped strand of wood cells that extends from the inner bark to the pith perpendicular to the axis of a tree trunk; rays appear as fleck on quartersawn surfaces of some species.

Rift Lumber

Diagonally grained lumber.

S1S

Surfaced One Face

S2S

Surfaced Two Faces

S3S

Surfaced Two Faces and Straight Line Ripped One Edge

S4S

Surfaced Two Faces and Straight Line Ripped Two Edges

Sapwood

New wood surrounding the denser heartwood.

Select

A clear board that is too short or narrow to be FAS.

Shake

A lumber defect that is a lengthwise separation of wood, usually along the growth rings.

SLR1E

Straight Line Rip One Edge

SLR2E

Straight Line Rip Two Edge

Softwood

Wood cut from coniferous trees belonging to the botanical group Gymnospermae.

Spalting

An attractive dark brown or black stain in some woods caused by decay.

Speck

A defect that’s caused by a fungus living in a tree, which appears as small white pits or spots.

Split

A separation of wood fibers that extends completely through a piece of lumber, usually at the ends.

Sticker

A piece of wood, typically _” square, that’s inserted at regular intervals between layers of green wood to assist the drying process.

Sticker Stain

Sometimes called shadow, it’s a stain that forms under the stickers in a stack of drying wood.

Stripe

A stripe or ribbon pattern that occurs when woods with interlocked grain (which slopes in alternate directions) are quartersawn.

Surfaced Checks

A drying defect that occurs when the surface dries too quickly in relation to the core.

Texture

The size of the cells in wood, described as ranging from coarse to fine; often confused with grain.

Twist

A form of warp where one corner of a board is not aligned with the others.

Wane

The presence of bark or a lack of wood from any cause along the edge or corner of a piece of lumber.

Warp

Any deviation of the face or edge of a board from flatness, or any edge that is not at right angles to the adjacent face or edge; the most common forms of warp are bow, cup, twist, and crook.