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

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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

Burl

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

CLF

     100 lineal feet.

Check

     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.)

Cupped

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

Decay

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

Defects

     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

Fiddleback

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

Figure

     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)

Heartwood

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

Honeycomb

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

Kerf

      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.

MBF

     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.

Millwork

     Lumber that has been manufactered 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 undetermind cause in hardwoods.

Moisture Content

     Percentage or moisture present in wood; degree of dryness.

Net Dimension

     Actual size of finished lumber.

NHLA

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

Nominal Dimension

     1 x 4 . . . . 1 x 5 . . . . 1 x 6 . . . . etc.

Pitch

     A resinous, gummy substance in firs and pines.

Pitch Pockets

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

Pith

     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.

Quarter-Sawn

     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.

SLRIE

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

S2S

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

S4S

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

SND

     Sap no defect.

Sapwood

     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.

Shake

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

Shorts

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

Shrinkage

     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.

Stain

     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.

Steamed

     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.

Tally

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

Tolerance

     Judgemental 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.

Twist

     Spiral warpage of board.

Wane

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

Wainscoat

     Short length (3' high) wall paneling.

Warp

     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.

W.H.A.D.

    Worm Holes a defect.

W.H.N.D.

     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.