ASTM D9-87(1999)
(Terminology)Standard Terminology Relating to Wood
Standard Terminology Relating to Wood
General Information
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Designation:D9–87(Reapproved1999)
Standard Terminology Relating to
Wood
This standard is issued under the fixed designation D 9; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Thedefinitionscontainedhereinconstitutealexiconoftermsofgeneralinterest.Definitionsinmore
specialized wood product or process use will be found in other standards. These include Practice
D 245,EstablishingStructuralGradesandRelatedAllowablePropertiesforVisuallyGradedLumber;
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Terminology D 907, Adhesives; Definitions D 1038, Terms Relating to Veneer and Plywood;
Nomenclature D 1165, Domestic Hardwoods and Softwoods; Definitions D 1554, Terms Relating to
Wood-Base Fiber and Particle Panel Materials; Definitions F 547, Terms Relating to Nails for Use
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with Wood and Wood-Base Materials; Methods D 2555, Establishing Clear-Wood Strength Values;
Definitions C 274, Terms Relating to Structural Sandwich Constructions.
allowable properties—mechanical properties of materials as basic stress (archaic)—the term once used for an allowable
prepared for design use. Allocwable properties of wood are property for clear, straight-grained lumber.
identified with stress-grade descriptions and reflect the batten—a narrow strip of lumber for covering the adjoining
orthotropicstructureofwood.Oftenconsideredsynonomous edges of roofing or siding, often designated as “batts.”
with allowable unit stresses, working stresses, and design birdseyes—small localized areas in wood with the fibers
stresses. indented and otherwise contorted to form small circular or
American softwood lumber standard—a voluntary product elliptical figures remotely resembling birds’ eyes on the
standard of the U. S. Department of Commerce which serves tangential surface. Common in sugar maple; rare in other
as a basis for the preparation and revision of industry- hardwood species.
sponsored grading rules for lumber. blemish—ingradinglumber,anythingmarringtheappearance.
American standard lumber—lumber conforming to the basic May not be classified as a defect.
provisions of the American Softwood Lumber Standard. board foot—a unit of measurement represented by a board 1
annual ring—the growth layer produced by the tree in a single ft long, 1 ft wide, and 1 in. thick. Abbreviation ft. b.m.; bd.
growth year, including earlywood and latewood. ft., fmb. In finished or surfaced lumber, the board-foot
bark—the layer of a tree outside the cambium comprising the measure is based on the nominal size. In practice, the
inner bark and the outer bark. working unit is 1000 board feet. Abbreviation M bd. ft.; M
inner bark—the layer of living bark (phloem) that separates B.M.; M B.F.
theouterbarkfromthecambiumandwhichinthelivingtree board measure—a unit of measurement of the volume in
generally is moist and soft. board feet of logs or lumber. Abbreviation B.M.
outer bark—the layer of dead bark outside the inner bark, boards—See lumber.
forming the exterior surface of the tree stem. The outer bark bole—the stem or trunk of a tree of size sufficient to yield
frequently is corky and dry. lumber, veneer, or poles.
bark product—an opening between annual growth rings that bolt—(1) a short section of a tree trunk or limb;
contains bark. Bark pockets appear as dark streaks on radial (2) a short log of a length suitable for peeling in a lathe for
surfaces and as rounded areas on tangential surfaces. veneer; and
(3) a short portion of a log prepared for production of
shingles, staves, etc.
bow—the distortion of a piece of lumber in which there is a
This terminology is under the jurisdiction of ASTM Committee D-7 on Wood
deviation in a direction perpendicular to the flat face from a
and are the direct responsibility of Subcommittee D07.91 on Technical Service.
straight line from end to end of the piece.
Current edition approved March 9, 1987. Published April 1987. Originally
published asD9–29T. Last previous editionD9–86.
boxed heart—the term used when the pith falls entirely within
Annual Book of ASTM Standards, Vol 04.10.
the four faces of a piece of wood throughout its length.
Annual Book of ASTM Standards, Vol 15.06.
boxed pith—See boxed heart.
Annual Book of ASTM Standards, Vol 15.08.
Annual Book of ASTM Standards, Vol 15.03. brashness—a condition that causes some pieces of wood to be
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relatively low in shock resistance for the species and, when star check—a heart check in which the separation extends in
broken in bending, to fail abruptly without splintering at more than one direction from the pith.
comparatively small deflections. surface check—a check occurring on the surface of a piece
bright-wood—wood free of stain or any discoloration. of wood, usually on the tangential face not extending
built-up timbers—an assembly made by joining layers of through the piece.
lumber together with mechanical fastenings so the grain of through check—a check that extends through a piece of
all laminations is essentially parallel. wood, or from a surface to the opposite or to an adjoining
burl—(1) a hard, woody outgrowth on a tree, more or less surface.
rounded in form, usually resulting from the entwined growth chip marks—shallow depressions or indentations in or on the
of a cluster of adventitious buds. surface of dressed lumber caused by chips or shavings
(2) in wood or veneer, a localized severe distortion of the getting embedded in the surface during dressing.
grain generally rounded in outline, usually resulting from chips—small fragments of wood chopped or broken by cuts
overgrowth of dead branch stubs, varying from 1/2 in. to such as by a planer, chipper, mechanical hog, hammermill.
several inches in diameter; frequently includes one or more clear—free of defects or imperfections.
clusters of several small contiguous conical protuberances, coarse grain—See grain.
each usually having a core of pith but no appreciable amount collapse—the flattening of single cells or rows of cells during
of end grain (in tangential view) surrounding it. the drying or pressure treatment of wood, characterized by a
cambium—the layer of cells that lies between the inner bark caved-in or corrugated appearance.
and the wood of a tree, that repeatedly subdivides to form compression failure—deformation of the wood fibers result-
new wood and bark cells. ing from excessive compression along the grain either in
cant—a log that has been slabbed on one or more sides, direct end compression or in bending. It may develop in
usually with the intention of resawing at right angles to the standing trees due to bending by wind or snow or to internal
widest sawn face. longitudinal stresses developed in growth, or it may result
cap—a horizontal wood member, generally square or near from stresses imposed after the tree is cut. In surfaced
square; used to crown and bind the top ends of upright posts lumber, compression failures appear as fine wrinkles across
and piles together as a unit and to support upper construc- the face of the piece.
tion. compression parallel to grain—compression, endwise (par-
casehardening—a condition of stress and set in wood due to allel to the grain). The imposition of a compressive stress
dryinginwhichouterfibersareundercompressivestressand that acts in a direction parallel to the grain of the wood, as in
inner fibers under tensile stress, a condition that often exists a column.
during subsequent processing. In commerce, the term often compression perpendicular to grain—compression, sidewise
connotes a degree of severity regarded as detrimental in use. (perpendicular to the grain). The imposition of a compres-
cell—a general term for the minute units of wood structure sive stress that acts in a direction approximately perpendicu-
having distinct cell walls and cell cavities including wood lar to the grain of the wood.
fibers, vessel segments, and other elements of diverse compression wood—abnormal wood formed typically on the
structure and function. lowersideofbranchesandinclinedtrunksofsoftwoodtrees.
cellulose—the carbohydrate that is the principal constituent of Compression wood is identified by its relatively wide annual
wood and forms the structural framework of the wood cells. rings, usually eccentric, relatively large amount of latewood,
center match—matched lumber with tongues and grooves sometimes more than 50 % of the width of the annual rings
precisely centered on the edges. in which it occurs, and its lack of demarcation between
characteristic—a distinguishing feature or trait. In grading earlywood and latewood in the same annual rings. Compres-
lumber and other wood products, a feature in or on the wood sion wood shrinks excessively lengthwise, as compared with
which by its nature, extent, and frequency of occurrence normal wood.
determines the grade or level of quality. conifer—a tree belonging to the order Coniferae, usually
check—a separation of the wood along the fiber direction that evergreen, with cones and needle-shaped or scalelike leaves,
usually extends across the rings of annual growth, com- and producing wood known commerically as “softwood.”
monly resulting from stresses set up in wood during season- crook—a distortion of a piece of lumber in which there is a
ing. deviation in a direction perpendicular to the edge from a
end check—a seasoning check occurring on the end of a straight line from end to end of the piece.
board or other piece of wood. cross break—a separation of the wood cells across the grain.
heart check—a check that extends across the growth layers Such breaks may be due to internal stress resulting from
inoneormoredirectionsfromthepithtoward,butnotto,the unequal longitudinal shrinkage or external forces.
surface of a piece of wood. A synonym is pith check. cross grain—See grain.
pith check—see heart check. cross section—a section of a stem, board, or other piece of
roller check—a crack in the wood structure caused by a wood taken at right angles to its longitudinal axis.
piece of cupped lumber being flattened between machine crosscut—to cut a board, timber, or log generally transverse to
rollers. the direction of the fibers. A synonym is “buck.”
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cull—in grading lumber or other wood products, pieces or fungi under conditions that favor such attack. In this con-
parts thereof, that do not meet the lowest quality standards nection the term “decay resistance” is more specific.
requirements. duration of load—the duration of stress or the time during
cup—a distortion of a board in which there is a deviation which a load acts on a member. In wood, a design consid-
flatwise from a straight line across the width of the board. eration for modifying allowable stresses, based on the
cut stock—a term for softwood lumber indicating the product accumulated loadings anticipated in the life of a structure.
generally has been manufactured to dimensions suitable for earlywood—the less dense, large-celled, part of the growth
a fabricating operation with little further processing re- layer formed first during the annual growth cycle. A syn-
quired. onym is springwood.
decay—decomposition of wood substance caused by action of end match—matched lumber with a tongue on one end of the
wood-destroying fungi, resulting in softening, loss of piece and a matching groove on the opposite end.
strengthandweight,andofteninchangeoftextureandcolor. equilibrium moisture content—a moisture content at which
advanced (or typical) decay—the older stage of decay in wood neither gains nor loses moisture to the surrounding air.
which the destruction is readily recognized because the extractives—compounds occurring in plant materials but not
wood has become punky, soft and spongy, stringy, ring- forming part of the structural elements, that are removed
shaked, pitted, or crumbly. Decided discoloration or bleach- with neutral solvents such as ether, alcohol, and water.
ing of the rotted wood is often apparent. face—the wide surface of rectangular pieces of lumber. Often
incipient decay—the early stage of decay that has not the surface that determines the grade of lumber destined for
proceeded far enough to soften or otherwise perceptibly remanufacture.
impair the hardness of the wood. It may be accompanied by fiber, wood—a comparatively long (1/25 in. or less to 1/3 in.),
a slight discoloration or bleaching of the wood. narrow, tapering wood cell closed at both ends.
pocket rot—advanced decay that appears in the form of a fiber saturation point—the moisture content at which the cell
hole, pocket, or area of soft rot usually surrounded by walls are saturated with water (bound water) and no water is
apparently sound wood. heldinthecellcavitiesbycapillaryforces.Itusuallyistaken
defect—any irregularity or imperfection in a tree, log, piece, as 25 to 30 % moisture content, based on weight when
product,orlumberthatreducesthevolumeofsoundwoodor ovendry.
lowers its durability, strength, or utility value. figure—the pattern produced in a wood surface by annual
degrade, n—a reduction in quality of lumber, logs, or other growth rings, rays, knots, deviations from regular grain such
wood products due to processing. as interlocked and wavy grain, and irregular coloration.
dense—(1) term used in stress grading of certain softwood fire retardant—having or providing comparatively low flam-
species to signify a high specific gravity. (2) a visual mability or flame spread properties.
estimate of high specific gravity. To be classified as dense, flat grain—See grain.
thesoftwoodspeciesshallaverageononeendortheotherof flitch—a portion of a log sawed on two or more sides and
each piece, not less than six annual rings per inch and intended for remanufacture into lumber or sliced or sawed
one-third or more latewood. Pieces not less than four rings veneer. The term is also applied to the resulting sheets of
per inch shall be accepted as dense if they average one-half veneer laid together in sequence of cutting.
or more latewood. form factor—a factor used in the calculation of the bending
depth factor—the factor included in deriving the allowable strengthofwoodmemberstocompensatefornonrectangular
bending stress for rectangular members which takes into shape. Defined as the ratio of the modulus of rupture of a
account the somewhat lower unit strength developed in member of desired shape to that of a “standard” member.
larger members as compared to smaller members. Archaic fracture toughness—a conventional fracture mechan
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