4/4 — Hardwoods are commonly sold in quarter-inch increments of thickness. 4/4 or “four-quarter” hardwood is one inch thick; 6/4 hardwood is 11/2 inches thick; 8/4 hardwood is two inches thick, etc.

alternate top bevel (ATB) (saw blade) — ATB blades have teeth that are angled across the top edge, alternating between a right and left hand bevel. The alternating beveled teeth form a knife-like edge on both sides of the blade, causing it to shear the wood fibers cleanly using a slicing motion, making a cleaner cut than flat top teeth. The steeper the bevel angle, the cleaner the teeth cut, but the quicker they dull. Most 40-tooth ATB blades are marketed as “all-purpose” blades. ATB blades give a smoother cut when crosscutting natural woods and veneered plywood.

bark pocket — A bark-filled blemish in the board.[NHLA]

bird peck — A patch of distorted grain resulting from birds pecking through the growing cells in the tree and sometimes containing a hole and/or ingrown bark.[NHLA]

blind dovetail joint

board foot — A board foot is a common unit used for measuring lumber. It is equal to 144 cubic inches, or the volume of a board 1 foot long × 1 foot wide × 1 inch thick. To calculate board feet use the following formula:
One board foot = Thickness (inches) × Width (inches) × Length (feet) ÷ 12

boxed heart — The term used when the pith falls entirely within the four faces of a piece of wood anywhere in its length.[NHLA]

burl — A burl is a swirl or twist in the grain of the wood which usually occurs near a knot but does not contain a knot. Those containing sound centers are admitted in the cuttings except when otherwise specified.[NHLA]

butt log

check — A lengthwise separation of the wood that usually extends across the rings of annual growth and commonly results from stresses set up in wood during seasoning.[NHLA]

combination (ATBR) (saw blade) — Combination blades have 50 teeth arranged in sets of five—four ATB teeth followed by a raker (FTG) tooth (thus the ATBR designation)—with a large gullet in between the groups. The ATB teeth are designed to crosscut cleanly while the raker teeth aid in ripping. Combination blades are also considered “all-purpose” blades.

cup — A distortion of a board in which there is a deviation flatwise from a straight line across the width of the board.[NHLA]

cutting — A portion of a board or plank obtained by cross-cutting or ripping, or by both. In the Common grades, a cutting shall be flat enough to surface two sides to standard surfaced thickness after it has been removed from the board. In the grades of Selects and Better, the entire board must be flat enough to surface two sides to standard surfaced thickness (for skip limitations, see page 50 under the rule “Clear-Face” Cutting Grade). Diagonal cuttings are not permitted.[NHLA] See also clear-face cutting, sound cutting.

clear-face cutting — A cutting having one clear face (ordinary season checks are admitted) and the reverse side sound as defined in Sound Cutting. The clear face of the cutting shall be on the poor side of the board except when otherwise specified.[NHLA] See also cutting.

sound cutting — A cutting free from rot, pith, shake and wane. Texture is not considered. It will admit sound knots, bird pecks, stain, streaks or their equivalent, season checks not materially impairing the strength of a cutting, pin, shot and spot worm holes. Other holes 1/4” or larger are admitted but shall be limited as follows: One 1/4” in average diameter in each cutting of less than 12 units; two 1/4” or one 1/2” to each 12 units and on one side only of a cutting.[NHLA] See also cutting.

decay — The decomposition of wood substance by fungi.[NHLA] See also incipient decay.

dimensional lumber

dovetail joint — __________. See also blind dovetail joint, half-blind dovetail joint.

F1F — First and Seconds, one face.

FAS — First and Seconds.

flat top grind (FTG) (saw blade) — FTG blades have teeth whose top edges are square to the saw plate. Also called rakers, these teeth cut wood in a similar manner to a chisel chopping out the ends of a mortise. They’re fast cutting and durable, but don’t produce a clean surface. They’re designed to rip, sawing parallel to the grain.

grades (hardwood lumber)

Clear-Face cuttings grades — In descending order of quality:


FAS One Face (F1F)


No. 1 Common

No. 2A Common — The designation A means the cuttings are clear, whereas B indicates the cuttings are only required to be sound.

No. 3A Common — The designation A means the cuttings are clear, whereas B indicates the cuttings are only required to be sound.

Sound cuttings grades — In descending order of quality:

No. 2B Common — The designation A means the cuttings are clear, whereas B indicates the cuttings are only required to be sound.

No. 3B Common — The designation A means the cuttings are clear, whereas B indicates the cuttings are only required to be sound.

Sound Wormy

green — Freshly sawn lumber, or lumber that has received no intentional drying; unseasoned.[NHLA]

half-blind dovetail joint

heartwood — The wood extending from the pith to the sapwood, the cells of which no longer participate in the life processes of the tree.[NHLA]

honeycomb — A cellular separation that occurs in the interior of a piece of wood, usually along the wood rays.[NHLA]

hygroscopic — Readily taking up and retaining water, especially from the atmosphere.

incipient decay — The early stage of decay that has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood. It is usually accompanied by a slight discoloration or bleaching of the wood.[NHLA]

lumber (shipping-dry) — Lumber that is partially dried to prevent stain and mold in transit.[NHLA]

lumber (stump-shot) — That having jagged or irregular ends, sawn from a butt log.[NHLA]

mineral streak — An olive to greenish-black or brown discoloration of undetermined cause in hardwoods.[NHLA]

NHLANational Hardwood Lumber Association.

nominal size — The nominal size of a board is its rough size before drying and planing. The shrinkage which occurs as the board is dried and during planing results in the final actual dimensions being slightly smaller in thickness and width than the nominal size.

pin knot — A knot which does not exceed 1/8” in average diameter.[NHLA]

pith — The small soft core occurring in the structural center of the log.[NHLA]



S4S — Surfaced on 4 sides.

sapwood — The living wood of pale color near the outside of the log.[NHLA]

saw blade — __________. See also alternate top bevel (ATB), combination (ATBR), flat top grind (FTG), and triple-chip grind (TCG).

seasoning (air-dried) — Dried by exposure to air, usually in a yard, without artificial heat.[NHLA]

seasoning (kiln-dried) — Dried in a kiln with the use of artificial heat.[NHLA]

shake — A separation along the grain, the greater part of which occurs between the rings of annual growth.[NHLA]

shooting board — A jig for woodworking which is used in combination with a hand plane to trim and square up the edges and ends of boards. See Wikipedia: Shooting board.

sidebend — A distortion of a board in which there is a deviation edgewise from a straight line from end to end of the board.[NHLA]

sound knot — A knot that is solid across its face, as hard as the surrounding wood, and shows no indication of decay.[NHLA]

snipe — A noticeably deeper cut on the leading and/or trailing end of a board after having passed through a thickness planer or jointer. Its cause, in a jointer, is an out-feed table which is set too low relative to the cutter head, or in a thickness planer, an unnecessarily high setting of the bed rollers of the in-feed table or a pressure bar which is set too high.[Wikipedia]

split — A lengthwise separation of the wood, due to the tearing apart of wood cells.[NHLA]

stain — 1. In hardwoods the word “stain” is used to describe the initial evidences of decay.[NHLA]

torsion box

triple-chip grind (TCG) (saw blade) — TCG blades have teeth that alternate between a raker tooth and a chamfered tooth. The chamfered tooth roughs out the cut, while the following FTG tooth cleans it up. This tooth configuration is meant for sawing dense materials: plastic laminate, solid surface materials like Corian, and non-ferrous metals like brass and aluminum. Pointy ATB teeth would blunt quickly from this stuff.

unselected — The full product of the log from which no separation for heartwood or sapwood has been made.[NHLA]

wane — 1. A defect in a plank or board characterized by bark or insufficient wood at a corner or along an edge, due to the curvature of the log. 2. Bark or lack of wood.[NHLA]

warp — Warp is any variation from a true or plane surface. Warp includes bow, crook, cup and twist, or any combination thereof.[NHLA]

worm hole

pin worm hole — One not over 1/16” in diameter.[NHLA]

spot worm hole — One over 1/16” but not more than 1/8” in diameter.[NHLA]

shot worm hole — One over 1/8” but less than 1/4” in diameter.[NHLA]

grub hole — One 1/4” in diameter or larger.[NHLA]


[NHLA]Rules for the Measurement and Inspection of Hardwood and Cypress”. National Hardwood Lumber Association. January 1, 2015. ( 2017-04-09)