Glossary of Terms – Hardwood Flooring – “A” Through “F”

Term Definition
Abrasion Wearing, grinding, or rubbing away by friction.
Resistance to a form of wear, in which a gradual removal of a flooring surface
is caused by the frictional action of relatively fine particles.  Abrasion resistance
generally depends on the toughness of the product or wearlayer, thickness of
wearlayer, and existence of surface coatings.
Acclimation The act of allowing wood moisture content to become at equilibrium with the
environment in which it is expected to perform (see EMC, Equilibrium Moisture Content).
Acid Chemical substance rated below 7 on the pH scale.
Acrylic Impregnated /
Acrylic- infused
The generic name for wood-plastic composites using wood impregnated with
acrylic monomers and polymerized within the wood cells by heat, pressure or radiation.
A translucent synthetic resin that is resistant to discoloration, moisture, alcohol acids,
alkalis and mineral oils.  It is usually made by polymerization of acrylic acid and methacrylic acid.
Adhesion The ability of a finish to stick to wood.
Air Dried Dried by exposure to air in a yard or shed without artificial heat.
Alkalinity A measurement of alkine rated above 7 on the ph scale.
Alligatoring   A finished that exhibits large segmented areas with the appearance  of an alligator hide. 
May be caused by heavy coating, coating over non-cured coatings, use of fast drying thinners
or the application of a finish over another with less elasticity
Amber A yellowish color change within the wood or finish or both. See Color Change.
Colors made from aniline oils or coal tar derivatives and used in the manufacture of wood stains.
Aniline dyes are made in different grades to be soluble in water, alcohol or hydrocarbons, and
accordingly are called water colors, spirit colors and oil colors, respectively.
Anisotropic   Not possessing the same properties in all directions.  Wood is anisotropic because the shrinking
and swelling, from moisture loss or gain, are unequal in length, thickness and width.
The layer of wood growth, including spring- and summerwood, formed on a tree during a single
growing season.
APA   Formerly called the American Plywood Association, it is now known as APA – The Engineered
Wood Association.
Wood underlayments approved by APA – The Engineered Wood Association.
 Associated with partially cured finishes.  When an applicator is drawn across the surface of half-set
finish, especially when applying a new section of finish, the lapped area is deglossed leaving a streak. 
Usually caused by thin films which have faster curing times than the surrounding area.  May also be
caused by inadequate agitation of satin and semi-gloss finishes which allows “settling” of glossing
A laminated paper that is used as a moisture retardant meeting Federal Specification UU-13-A
A moisture retardant paper saturated with asphalt meeting ASTM Standard D4869.
Bark    In wood anatomy, a non-technical term used to describe all the tissues outside the wood (xylem)
cylinder.   In older trees, bark is usually divisible into inner (living) and outer (dead).
Bark Pocket Ingrown bark that becomes visible when the board is machined and sanded.
Base Shoe A molding designed to be attached to baseboard molding to cover expansion space.
See Rift Sawn
Beetle A small insect, which, in the adult and larvae states, bores in the bark or between the bark and wood
of living trees, fallen trees and logs.  May degrade the wood products.
An angular edge and/or end treatment used on flooring.
A small hole or patch of distorted grain resulting from birds pecking through the growing cells in the
trees; it is usually accompanied by discoloration extending for considerable distance along the grain.
Small localized areas in wood with the fibers indented and otherwise contorted to form few to many
small circular or elliptical features remotely resembling a bird’s eye on the tangential surface.  Common
in redwood and in sugar maple.
Bit Ends
Planer bites on the ends of a board.
End Match
When either end of a piece of flooring is not end-matched.
Blister   A raised spot on the surface of a floor similar in shape to a blister on human skin.  How soon after
installation a blister develops can help determine the cause. Blisters which occur within a few hours
are usually due to a concentration of trapped air.  Blisters which occur at a later time often indicate the
presence of moisture in the substrate, or delamination of materials or adhesives.
A condition in wood finish where the surface finish has dried and some stain that has penetrated the
wood re-emerges to the face.  It usually makes a pattern of small spots about 1/16″.  Wiping with a dry,
white towel normally identifies the presence of the problem which can be prevented by buffing with a
red or white pad.
Bleeding When the color of a stain or other coating material works up into succeeding coats, imparting to them a
certain amount of color, it is said to bleed.  A non-bleeding color is one that isn’t soluble in materials
used over it.
Blistering   The formation of bubbles or pimples on the surface of finished work.  It is caused by exposure to
excessive heat, grease or other volatile material under the finish, by moisture in the wood or by the too
frequent application of coats.  Anything that causes a gas or vapor to form under the film may cause
Blushing The formation of a white or grayish cast in a spirit varnish, shellac, epoxy or lacquer film during the drying
period.  It is caused by the partial or total precipitation of the solid ingredient as a result of condensed
moisture in the film.  This may be caused by excessive humidity or by use of an improper solvent.
A unit of measurement equal to a board 1′ long, 1′ wide, and 1″ thick; (abr. FMB.: bd. ft.)
Body Often used to describe the consistency of viscosity of a finishing material.  It’s also used to describe the
fullness or thickness of film on the work.
The temperature at which the vapor pressure of a liquid equals the air pressure, or the temperature
at which a liquid begins to boil or become gaseous.
Bond The adhesion between two materials.
Borders Simple or intricate designs which frame and customize a flooring installation
In wood technology, moisture that is intimately associated with the finer wood elements of the cell wall
by absorption and held with sufficient force to reduce the vapor transmission.  
Bowing A type of warping in which a piece of plank laid flat on a flat surface will be raised in the center or at
the ends.
( Boxed
When the pith falls entirely within outer faces of a piece of wood anywhere in its length, it is said to
contain boxed heart.
Brashness   A condition that causes some pieces of wood to be relatively low in shock-resistance for the species and,
when broken in bending, to fail abruptly without splintering at comparatively small deflections.
Also affects drying rate.
Bright   The term is applied to wood that is free from discolorations. The term bright sapwood is sometimes used
to describe sapwood of  natural color or in which the stain or discoloration can be removed by surfacing
to standard thickness.
The term bright describes the natural un-stained color of sapwood.
Broken corners consist of small pieces of wood being torn out during matching at the ends.  Rough
handling may cause them also.
Broken edges consist of a small area of the wood being torn out or indented along the edge.
A knot with a crack or check through the center.
A streak that is brown in color
Marks of the brush that remains in the dried film of a finishing material.  They are caused by working
the material after its solvents have evaporated to the point that the flowing power has been lost or by
defects in formulation that prevent the material from leveling out after it has been brushed.  May also
be caused by the size of the bristle and its composition.
Brushability The ease with which a material can be applied with a brush under practical conditions.
Bubbling The appearance of bubbles in the film of finish while a finishing material is being applied.  It is caused
by any condition that causes air, vapors or gases to be trapped in the film while it’s soft, but after it has
hardened sufficiently to prevent the gas from escaping.
Buckle  Adhesive failure when a floor is under compression.  It is caused by subfloor movement or floor growth.
A finishing material, usually of a transparent nature, used over the sealer or color coats and under the
finishing coats to increase the fullness of the finished work.
Bundle   A parcel of relatively small sawed, machined, or other wood products assembled and bound together
to facilitate handling, e.g., lathe, molding, or split items.  The bundle, usually bulk piled, may be bound
with twine, wire, or strap.
 Burl 1.  A hard, woody outgrowth on a tree, more or less rounded in form, usually resulting from the entwined
growth of a cluster of adventitious buds.  Such burls are the source of the highly figured burl veneers
used for purely ornamental purposes.

2.  In wood or veneer, a localized severe distortion of the grain generally rounded in outline, usually
resulting from over growth of dead branch studs, varying from 1/2″ to several inches in diameter;
frequently includes on or more cluster of several small contiguous conical protuberances, each usually
having a core, but no appreciable amount of end grain (in tangential view) surrounding it.  
Cambium The thin layer of generative tissue lying between the bark and the heartwood.  Cambium produces new layers
of upward conducting tissue (xylem) on the inside and downward conducting tissue (phloem) on the outside
thus increasing the diameter of the trunk.  All cells of the wood and of the bark originate in the cambium
and is therefore known as the “Seat of Tree Growth” of the tree.
Slight indentations causing a ripple effect on the surface of a wood floor.  They are usually caused by sanding
machines that have out-of-balance or out of round sanding heads, bad drive belts or foreign objects stuck to
the wheels.  The marks are most noticeable on gloss finishes, in direct-light areas or at eye level.
Check(s) A rupture or opening along the grain of the wood, which develops in seasoning.
Similar to alligatoring, except that the finish is broken into smaller segments.  Crowfoot checking is the name
given to the defect when the breaks in the film form a definite three-prong pattern with the breaks running
outward from a central point of intersection.  When the checks are generally arranged in parallel lines, the
defect is known as line checking.  Irregular checks without a definite pattern are known as irregular checking.
An area in which pieces of wood have been pulled or chipped away from the surface during machining.
Classification of
In grading, grain can be defined as referring to the arrangement of direction of the annual rings.
Cleat A barbed fastener commonly used as a mechanical device to fasten hardwood flooring.
Visual changes in the color of the wood species caused by exposure to light, deprivation of light and air,
oxidation or other chemical reaction.
Caused when wood strips or parquet slats absorb excess moisture and expand so much that the cells along
the edges of adjoining pieces in the floor are crushed.  This causes them to lose resiliency and create cracks
when the floor returns to its normal moisture content.
Coniferous See Softwoods.
See Swedish Finish.
Crazing The appearance of minute, interlacing cracks or checks on the surface of a dried film of finishing material.
Crook The distortion of a board in which there is a deviation, in a direction parallel to the edge, from a straight line
from end to end of the piece.
Laying of material perpendicular or at an angle to the material below it.
A condition occurring at an end-joint with the ends of flooring strips pulled in opposite directions by
movement of the subfloor.
Crowfooting A form of finish crystallization wherein small lines are visible coming together at a central point.
Crowning A “convex” or “crowned” condition or appearance of individual strips, with the center of the strip higher than
the edges.  (Opposite of cupping)
Cull In lumber grading, pieces or parts that conform to no grading standards.
Cupping A “concave” or “dished” appearance of individual strips, with the edges raised above the center. 
(Opposite of crowning)
Cure A chemical process in which a material reaches its functional state.  Such as cured finish, paint, concrete, etc.
Cut  To sand a floor.  As a noun, cut refers to one pass over an area of floor with sanding equipment.  Usually,
in sanding a floor two or more cuts with progressively finer grits of sandpaper are performed.  
Large amounts of mineral and/or mineral streaks that prominently discolor the piece.
Decay The decomposition of wood substance by fungi.

Advanced stage decay  The older stage of decay in which destruction is readily recognized because the wood
has become punky, soft and spongy, stringy, ring shanked, pitted or crumbly.  Evident discoloration or
bleaching of the rotten wood is often apparent.

Incipient stage 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.

Intermediate stage decay  A stage, in which some breakdown of the normal wood structure is noticeable,
but which does not yet present the characters of the advanced stage of decay or effect the structural integrity
of the wood in general.
Deciduous See Hardwoods.
Defect Any irregularity or imperfection in a tree, log, bolt, lumber or other wood product that reduces the volume of
useable wood or lowers its durability, strength, or utility or visual value.  Defects may result from knots and
other growth conditions and abnormalities; from filling, drying, machining, or other processing procedures.

Drying Defect  Any irregularity occurring in or on wood, as a result of drying, that may lower its utility value.

Drying Defect  Chemical Action  A discoloration of wood caused by chemical modification resulting in sticker
stain or marking, brown stain, etc.

Drying Defect  Fungus  Any deterioration in quality caused by the growth of fungi on the surface or in the
interior of the wood such as blue stain, sap stain, decay, mold, etc.

Drying Defect  Shrinkage  Any irregularity occurring in wood resulting from shrinkage during drying, such as
surface checks, end checks, honeycombing, splitting, warp, loose knots, knotholes, etc.
Delamination The separation of layers in an engineered/laminate through failure within the adhesive or at the bond between
adhesive and laminate.  Term is often used incorrectly to identify a failure of finish to adhere to the surface
of the wood.  See Adhesion.
Certain hardwoods in which the pores tend to be uniform in size and distribution throughout each annual ring
or to decrease in size slightly and gradually toward the outer border of the annual growth ring.  Hard maple
is an example.
The ability of a material to retain its original size and shape without appreciable shrinkage and/or expansion
after temperature or humidity change.
Discoloration Change in color of wood due to fungal and chemical stains, weathering and heat treatment.
Dispersed In reference to finishing materials, finely divided or colloidal in nature.
Distressed A heavy texture in which the floor has been scraped, scratched, or gouged to give it a time-worn antique look.
  (A common method of distressing is wire brushing).
Drier A catalytic material that improves the drying or hardening properties of oils or varnishes when added in small
amounts.  They are usually organic salts of lead, cobalt, manganese, zinc and iron, such as naphthenates,
resinates and linoleates.
Dry Kiln A room, chamber or tunnel in which the temperature and relative humidity of air circulated through parcels
of lumber, veneer, and other wood products can be controlled to govern drying conditions.
Dry Rot In wood, any decay attacking both the cellulose and lignin producing a generally whitish residue that may
be spongy or stringy or occur in pockets.
The stage of solidification of a film of finishing material when it doesn’t feel sticky or tacky when a finger is
drawn lightly across it in a quick continuous motion.
Dry to
That stage of solidification of an applied film of finishing material when it can be sanded without undue
softening, sticking or clogging of the sandpaper.
Dry to
That stage of drying of a film of finishing material when it has solidified sufficiently that it can be touched
lightly without any of the finishing material adhering to the fingers.
Drying The act of changing from a liquid film to a solid film by the evaporation of solvents, oxidation, polymerization
or by a combination of these phenomena.
Drying characteristics occur during the drying process. Examples include: Checks, Split, Warp (including cork,
cup, bow, and twist) and Honeycomb.
Drywall Interior covering material, such as gypsum board, hardboard or plywood, that is applied in large sheets or
Durability The ability of the wood species or finish to withstand the conditions or destructive agents with which it comes
in contact in actual usage.
Small particles of solid matter. Also, A grading or size of natural resin.
Dust-free That stage of solidification of an applied film of finishing material when dust that settles on the coated surface
won’t penetrate or stick to the film.
The chamfered, or beveled edge, of strip flooring , plank, block, and parquet.
Electrodes In testing wood for moisture content, devices made of electrically conducting material for connecting wood
into the electric circuit of an electric moisture meter.

Insulated Electrodes  In testing wood for moisture content, special electrodes for use with resistance-type
electric moisture meters that are coated with an insulating material to limit or control the point of contact
between the electrode and the wood.
The place where two pieces of flooring are joined together end to end.
In strip and plank flooring the ends of individual pieces have a tongue milled on one end and a groove milled on
the opposite end, so that when the individual strips or planks are butted together, the tongue of one piece
engages the groove of the next piece.
Engineered An assembly made of adhesive bonded layers of wood in which adjacent layers are normally at right angles to
the adjoining layers which increase dimensional stability.
Epoxy Ester
A varnish that, with the addition of epoxy, creates a hybrid with the advantages of both products.  Ambers well
with quick build and high gloss but can be difficult to repair.  Enhanced working characteristics make this finish
a preferred choice for athletic surfaces.  Dries to tack free in 8-24 hours, reaching full cure in 30 days.
The moisture content at which wood neither gains or loses moisture when surround by air at a given relative
humidity and temperature.
Face The wide surface of rectangular shaped pieces of flooring. Often the surface that determines the grades.
Wrinkle appearing on the surface of adhered flooring. This is normally caused by severe compression of the
flooring, normally associated with hard set, firm bonding adhesives over shrinking substrates.
Fading The loss of color due to exposure to light , heat or other destructive agents
The tapering of the edge of film of dried material either by the method of application, sanding or rubbing the
dried film, resulting in a gradual progression of the film thickness from little or no material at the edge to a
normal coating at the center.
A strip of wood used at a threshold or to border a room or to otherwise serve as an accent. Usually of a
contrasting color or species.
The stage in the drying or wetting of wood at which the cell walls are saturated with water (bound water) and
the cell cavities are free of water. Most species reach reach their fiber saturation point at 28-30% moisture content,
based on the weight when oven dry. wood neither expands nor contacts at its fiber saturation point.
Figure Inherent markings, design, or configurations in the surface of the wood produced by the annual growth rings, rays,
knots and deviations from regular grains.  
Filler Inherent markings, designs, or configurations in the surface of the wood produced by the annual growth rings,
rays, knots and deviations from regular grain.
In woodworking, any substance used to fill the holes and irregularities in planed or sanded surfaces to decrease
the porosity of the surface before applying finish coatings.  Wood filler used for cracks, knotholes, worm holes, etc.
is often a commercial putty, plastic wood or other material mixed to the consistency of putty.  A wood filler may
also be mixed on the job using sander dust from the final sanding, or other suitable material, mixed with sealer
or finish.  
Fillets The small components which comprise parquet. Also called fingers or slats.
Fills Openings in the surface of the flooring, which would be filled with wood putty.
Fine pin worm holes are 1/32″ or less in diameter.
Parquet made from small strips of wood assembled together. See Fillets.
Flag A heavy dark mineral streak shaped like a banner.
one or more worm holes surrounded by a mineral streak.
The propagation of a flame away from the source of ignition across the surface of a liquid or solid, or through the
volume of a gaseous mixture.  Note:  Most wood species are Class C Flame Spread unless the wood floor has been
treated and marked.
A material added to a normally glossy coating to reduce luster and produce a flat appearance.
Flecks The wide, irregular, conspicuous  figure in quarter sawn oak flooring.  Also known as ray flecks.
Flooring that adheres board to board  at edge and end joints, without direct attachment to the subfloor.
Flow The characteristic of a coating that allows it to level or spread into a smooth film of uniform thickness before
A type of viscosimeter originally used by the Ford Motor Company, but now used extensively in testing laboratories. 
It consists of a cup with an overflow device to ensure a standardized volume, in the bottom of which is a
standardized orifice.  The number of seconds required for the cup to empty itself at a standardized temperature
gives a numerical expression of the viscosity of the material.
Fungi Low forms of plants consisting mostly of microscopic threads (hypea) that traverse wood in all directions, dissolving
materials out of the cell walls that they use for their own growth.
Roughening of the surface of the wood, resulting from absorption of moisture sufficient to expand the wood cells
at the immediate surface.  The result is a fuzzy feel when touched.
Updated on September 22, 2022