Dayspring’s handy reference guide for commonly used Wood Terms:

4/4″ = 1″ (inch) Piece of Wood:
Standard industry practice to express wood thickness in quarters of an inch (i.e. 5/4″ = 1 1/4″)

Bird Peck:
A patch of distorted grain resulting from birds pecking

Bird’s Eye:
Small decorative circular figure, common in hard maple and brazilian cherry

Board Foot:
A piece of lumber 1 inch thick, 12 inches wide, and 1 foot long

A swirl or twist in the grain of wood which does not contain a knot

100 lineal feet.

A lengthwise seperation in the wood surface caused by rapid or faulty seasoning.

Close Grain
Wood with narrow growth rings.

Color Change
Most woods darken after finishing if not constantly exposed to the sun’s rays. (Walnut is an exception.)

A convex board with one or both edges higher than center.

Disintegration of wood substance due to the action of wood-decaying fungi

The most common defects includes knots, worm holes, bird peck (bark pockets), wane, stain, pitch, checks, unsound burls, shake and split.

Dimension Lumber
Lumber cut, or S4S, to predetermined specific width (sometimes also to length.)

End Check
Separation of the wood fibers at the end of a board.

End Grain
Lumber grain as seen from one end of the board.

End Matched
Tongue and grooved on the ends of boards as well as the sides ( as in Oak flooring).

Equalizing in kiln drying
Obtaining the same moisture content from board to board in a charge or lumber

A grain characteristic that has a rippled appearance. (Maple, Mahogany, and Sycamore)

Unusual wood grain patterns.

Green Lumber
Freshly sawn; Unseasoned.

Growth Rings
New wood formed by the annual growth of a tree. (Also called annual rings)

The central supporting column of the tree trunk, consisting of matured wood in which little further change will occur.

The cellular separation that occurs in the interior of a board, usually along the wood rays.

The path that any saw makes in the process of cutting.

Lineal Feet (Lin. Ft.)
A board one foot in length, regardless of width or thickness.

One thousand board feet.

Medullary Rays
Radial vertical tissues, extending across the growth rings of a tree, that enable the transmission of sap and produce a decorative spotted figure in quartersawn boards.

Lumber that has been manufactured by being run through such milling machines as a planer, straight line rip, etc.

Mineral Streak
An olive to greenish-black or brown discoloration of undetermined cause in hardwoods.

Moisture Content
Percentage or moisture present in wood; degree of dryness.

Net Dimension
Actual size of finished lumber.

National Hardwood Lumber Association, P.O. Box 34518, Memphis, Tennessee 38134

Nominal Dimension
1 x 4 . . . . 1 x 5 . . . . 1 x 6 . . . . etc.

A resinous, gummy substance in firs and pines.

Pitch Pockets
Defects resulting from resin accumulated between the growth rings in softwoods.

The small soft center core of a tree around which growth takes place.

Plain (Flat) Sawn
Lumber sawn together to the tree’s annual rings. Most lumber is Plain Sawn. Advantages in plain Sawing: 1. Less costly and wasteful, hence more available; 2. Easier to kilm dry; 3. Averages wider widths.

In commercial practice, lumber cut with rings (see either end of the board) at angels or 45 degrees to straight up 90 degrees i.e. parallel or almost with medullary ray. In oak it produces spotted figure; in mahogany a ribbon-stripe. Advantages in Quarter Sawing: Shrinks, twists, cups, checks, and splits less.

Random Lengths and Widths (RW&L)
The fact that hardwoods are almost always offered in a random width and length assortment can present something of a mystery. The question: “Why aren’t Birch, Oak, and Walnut produced in convenient dimension sizes like Pine, Redwood and Fir?” Answer: hardwood lumber is cut to yield the maximum of usable material and minimize waste. Both widths and lengths are, therefore, random and even the best grades allow for occasional defects.

Rift Sawing
Rift sawing is midway between quarter-sawing and plain sawing. It offers the same figure consitency as quarter-sawing but develops a more subtle grain figure.

Rough (RGH)
The board as it comes from the saw. Not surfaced.

Straight-Line ripped one edge to give one true glue edge.

Surfaced (machines to a smooth finish) on two sides; edges are rough.

Surfaced (machined to a smooth finish) on all four sides.

Sap no defect.

The lighter-colored wood growing between the heartwood and bark.

Seed Tree
A tree which is spared during the lumbering process for the purpose of providing a source of seed for restocking the cut-over area.

Selective Cutting
The practice of only cutting mature trees for lumber.

A lengthwise separation of wood, occuring before the timber is cut into lumber, usually resulting from violent storms or in felling the log.

High-Quality lumber shorter than standard grade. (Less than 6 feet long)

Decrease in the volume or dimension of wood as a direct result of the drying process. Greatest in hardest woods. Plain sawn boards will usually shrink twice as much as quarter-sawn.

Discoloration in the lumber cause by decay, fungi, etc. Normally avoidable through proper handling in the cutting and drying stages. Also, a finishing substance for coloring wood.

This term refers to a special process in which the green lumber (usually Walnut or Cherry) is steamed in vats for the purpose of darkening sapwood to blend with heartwood color.

Straight Grain
The board’s principle wood grain runs parallel to it’s length.

Straight-Line Ripping
Produces a perfectly straight edge which is ready for gluing.

Surface Check
The separation of the wood fibers, producing small, shallow, length-wise separation of wood along the board’s surface.

A record of the number of pieces and footage by grade.

Judgmental decisions for acceptable “give or take” variance from rules and dimension specifications.

Tongue and Grooved (T&G)
Tongue and grooved on sides of board so that the tongue edge of one board fits into the gooved edge of the next board.

Tongue and Grooved & end matched (T&G & EM)
Tongue and grooved on both sides and at both ends of piece, as in oak flooring.

Torn Grain
A defect in which fibers below the dressed surface are torn by the planer or cutters.

Spiral warpage of board.

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

Short length (3′ high) wall paneling.

Distortion in whish board turns or twists out of shape. Especially prevalent in woods of uneven density, e.g., spawood and heartwood of contrasting hard-soft annual growth. Also results from applying finishes, veneers, laminated plastics, etc. to one side of the piece only.

Worm Holes a defect.

Worm holes no defect.

Worm Holes
Voids in the wood cause by the burrowing action of certain wood infesting worms, which do not survive the kiln-drying process.