Common Lumber Terms
4/4” = 1” (inch) – It is a practice among lumbermen to express the thickness of cabinet grade lumber in quarters of an inch. Hence: 4/4”=1” and so on up to 16/4”=4”.
Air-drying (AD) – Wood that has been dried naturally to have moisture content of about 18%. Not a complete drying process! Lumber is piled in alternating layers separated by narrow sticks to permit air circulation around lumber with minimal stain.
Backing Board – The board remaining on faceplate after slicing veneer.
Band Sawn – Saw blade tooth markings (kerf) on face are at right angle to edge of board.
Bird Peck – A patch of distorted grain resulting from birds pecking; sometimes containing ingrown bark.
Bird’s Eye – Small, decorative, circular figure common in Hard Maple.
Board Foot – A piece of lumber 1 inch thick, 12 inches wide and 1 foot long, or its cubic equivalent.
Book Matched – Adjacent veneer sheets are opened like a book, matching the back of one sheet with the face of the next. Opposite slant of grain creates a light and dark effect.
Burl – A burl is a swirl or twist in the grain of the wood which does not contain a knot.
CLF – 100 lineal feet
Chatter Marks – Bumpy surfaced lumber
Circular Sawn – Saw Blade tooth markings are curved on face of board.
Clear Face Cutting – A cutting having one clear face and the reverse side sound as defined in Sound Cutting.
Close Grain – Wood with narrow growth rings.
Course Grain – “Rapid Growth” wood with wide growth rings.
Color Change – Most wood darkens after finishing if not constantly exposed to sun’s rays. (Walnut is an exception.)
Conditioning in Kiln Drying – Obtaining the same moisture content in the “shell” or outside surface of the board as there is in the “core” or center of the board.
Cutting – A portion of a board or plank obtained by cross-cutting or ripping, or by both. Diagonal cuttings are not permitted.
Cupped – A convex board with one or both edges higher than the center. Cup is always to sap side.
Decay – Disintegration of wood substance due to the action of wood destroying fungi.
Deciduous – The term given to broad-leaved trees which shed leaves annually. Example: Ash, Oak and Walnut.
Defects – The most common defects include knots, worm holes, bird peck (bark pockets), wane, stain, pith, checks, unsound burls, shake and split.
Delamination – The separation of veneers in plywood through failure of the adhesive.
Density – Wood weight per unit volume. Durability, hardness and toughness usually increase with density.
Dimension Lumber – Lumber cut or S4S to predetermined specific width (sometimes also to length) 1”x4”, 2’x4”, 2”x6”, 4”x4” – 8”, etc. (Note: both hardwood and softwood dimension lumber are often piece tallied and are S4S to 1/2” to 3/4” off nominal width and 1/4” to 1/2” off nominal thickness.)
Dowel – A round pin or peg of wood used to fit together separate wooden units.
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 ends of boards as well as the sides ( as in Oak flooring).
Even Texture – Uniform texture showing little contrast between spring growth and summer growth.
Equalizing in Kiln Drying – Obtaining moisture content from board to board in a charge of lumber.
Fiber board (MDF) – Panel board made from wood fiber or pulp bonded with adhesive; plywood substitute.
Fiddleback – A grain characteristic that has a rippled appearance. (Maple, Mahogany and Sycamore). Figure – Unusual wood grain pattern.
Flakeboard (Particle Board) – A board composed of wood flakes bonded together with a synthetic resin or other suitable binder under heat and pressure.
Flitch – 1) A hewn or sawed log or section of a log made ready for cutting into veneers by shaping up the edges; 2) After cutting a complete bundle of thin sheets laid together in sequence as they were sliced or sawn.
Foot – (1’) Total length of 12”.
Grain – The lengthwise pattern of wood fibers.
Green Lumber – Freshly sawn;unseasoned.
Gross Tally (Green Tally) – The actual board feet measured before kiln drying. When kiln dried lumber is sold on this basis, the buyer can expect to receive approximately 7% less board feet because of shrinkage in the kiln drying process.
Growth Rings – New wood formed by the annual growth of a tree. (Also called annual rings.)
Hardwood – The wood of any broad leaved tree bearing its seeds in a closed cavity. This term does not relate to the density of the wood.
Heartwood – The central supporting column of the tree trunk, consisting of matured wood in which little further change will occur.
Honeycombs – A cellular separation that occurs in the interior of a board, usually along the wood rays.
Improved Wood – A type of lumber made by soaking hardwood veneers with synthetic resins. Heat and pressure produce a strong durable product much heavier than natural wood.
Inlay – A design in the surface of furniture formed by inserting other woods and materials.
Kerf – The path that any saw makes in the process of cutting.
Kiln-Drying – Artificial method of drying lumber by forcing heated air to circulate around the lumber in an enclosed building.
Kiln-Dried (KD) – Wood that has been artificially dried. Typical moisture content is 8% or less in hardwoods and 13-19% in softwoods.
Knot – A circular, woody fiber in a board that once formed the base of a branch or twig growing from the trunk of a living tree.
LFE – Low Formaldehyde Emission
Lineal Feet (Lin.Ft.) – A board one foot in length, regardless of width or thickness.
Logging – The process of cutting trees and moving the logs to the sawmill.
Luster – Reflection of light sheen on wood surface caused by the undulating fibers and cell contents.
MBF – Thousand board feet.
Marquetry – An inlaid work of wood made from many different veneers. Used for decorative application.
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 quarter-sawn boards.
Millwork – 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. Often accompanied by worm holes.
Moisture Content – Percentage of moisture present in wood.
Mouldings – Long strips of wood which have been shaped to contours for ornamentation.
NHLA – National Hardwood Lumber Association
Net Measure – The actual measurement of hardwood lumber after kiln drying with no addition of footage for kiln-drying shrinkage.
Open Grain – Hardwoods with widely separated annual rings.
Parquet – A geometric pattern of wood floorings.
Pecky – Localized patches of arrested decay on the board surface. (Most common to Bald Cypress)
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 tangent to the tree’s annual rings. Most lumber is Plain Sawn. Advantages in Plain Sawn: (1) less costly and wasteful, hence more available (2) easier to kiln dry (3) averages wider widths.
Planed –Machine dressed to a smooth surface.
Plasticity – The property that describes a wood’s ability to retain its shape when bent. (see toughness)
Plywood – Sheet stock made from layers of veneers or plies, glued together with grain alternating in direction to counteract shrinkage and warpage.
Porous – This term refers to hardwoods only as all softwoods are non- porous. Typical woods are generally “diffuse porous” because growth is uniform throughout all seasons. By contrast, Oak is “ring porous” since the “spring growth” is softer and coarser than the summer growth.
Pulp – Wood fibers, ground and suspended in water, from which paper is made.
Quarter-Sawn – In commercial practice lumber cut with rings (see either end of board) at angles of 45 degrees to straight up 90 degrees…i.e. ., parallel or almost parallel with medullary ray. In Oak it produces spotted figure; in Mahogany a ribbon-stripe. Advantages in quarter sawing: lumber is more stable due to reduced shrinkage, twisting, checking, cupping and splitting.
Random Widths and Lengths – (RW&L) The fact that hardwoods are almost always offered in a random width and length assortment can present something of a mystery. One is inclined to wonder, “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 occasional defects.
Resin – A vegetable liquid or semi-liquid exudes from certain species of trees, particularly the pine tree. Pine resin is the source of naval stores.
Rift-Sawing – Rift-sawing is midway between quarter –sawing and plain sawing. It offers the same figure consistency as quarter-sawing but develops a more subtle grain figure.
Roey – Short, broken ribbon or strip figure caused by spiral formation of the fibers, or interlocked grain in the growth of rings. Produces alternate bands of varying shades of color.
Rough (RGH) – The board surface as it comes from the saw.
SLR1E – Straight line ripped one edge to give 1 true glue edge.
S2S – Surfaced (machined to a smooth finish) on two side;edges rough.
S4S – Surface (machined to a smooth finish) on all four sides.
SND – No sap defect.
Sapwood – The lighter-colored wood growing between the heartwood and bark.
Seasoning – Reduction of moisture content of wood to lighter weight and increased stability.
Second-Growth Timber – The forest growth which follows either partial or total cutting of the original forest.
Seed Tree – A tree which is spared during the lumbering process for the purpose of providing a source of seed for restocking the over-cut area.
Selective Cutting – Method of timber harvesting in which certain trees are cut for specific purposes.
Shake – A lengthwise separation of the wood occurring 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. Plain sawn boards will usually shrink twice as much as quarter-sawn.
Skip Dressing – An area on the board face missed by planer surfacing knives.
Slip Matched – Veneer sheets joined side by side to convey a sense of repeating figure. Most common in quarter-sliced veneers.
Softwood – The non-porous wood of any cone-bearing, needle leaved tree, regardless of whether the wood is hard or soft.
Sound Cutting – A cutting free from rot, pith, shake and wane. It will admit sound knots, bird pecks, stain, streaks or pin, shot and spot worm holes.
Sound Knot – A knot which is solid across its face, as hard as the surrounding wood, and shows no indication of decay.
Square Foot – An area 12”x 12” or the equivalent of 144 square inches without regard to thickness.
Stain – Discoloration in lumber caused 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 principal wood grain runs parallel to its length.
Straight Line Ripping (SLR) – Produces a perfectly straight edge that is ready for gluing.
Straitoplane – A double surface, face jointing planer-without pressure- developed by the Oliver Machinery Co.
Stripe – A grain pattern often seen in tropical hardwoods caused by the spiral growth formation in the trunk.
Surface Check – The separation of the wood fibers producing small, shallow, lengthwise separation of wood along the board’s surface.
Surface Measure (SM) – Measuring method used for hardwood grade inspection. Same as square footage. Surfacing – See S2S
Tally – A record of the number of pieces and footage by grade.
Tolerance – 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 grooved 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.
Toughness – The property that allows wood to bend without breaking (see Plasticity.)
Twist – Spiral warpage of a board.
Uneven Grain – Wood in which the growth rings deviate in width.
Uneven Texture – Wood which has considerable contrast between spring and summer wood. (See porous)
Veneers – Sliced or peeled thin sheets of wood for gluing to other veneers or to some other base material. Most hardwood veneers are used for decorative purposes.
Vertical Grain (VG) – A softwood term meaning the grain on quarter sawn boards ; close ring grain.
Wane – The presence of bark, or the lack of wood from any cause, on the edge or corner of a piece of lumber.
Wainscot – Short length (32” high) wall paneling.
Warp – Distortion in which board turns or twists out of shape. Especially prevalent in woods of uneven density, e.g. sapwood 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 caused by the burrowing action of certain wood-infesting worms which do not survive the kiln-drying process.