Glossary of Terms – Hardwood Flooring – “S” Through “W”

Term Definition
A dip in the surface of a sanded board caused by a hesitation inthe feeding of the board
through the sander.
SapwoodIn wood anatomy, the outer layer of the stem that in the living tree contain living cells and
reserve materials, e.g., starch. The sapwood is generally lighter in color than the heartwood.
Saw marks are marks left when the lumber was manufactured and remain after the flooring
is surfaced.
Scratches Slight incisions, breaks, tears or indentations on the surface caused by abrasive friction.
ScreedsUsually a 2×4 inch (50mm by 100mm) piece of wood laid flat side down and attached to a
concrete subfloor to provide a nailing surface for tongue-and-groove strip flooring or a wood
Sealer Any finishing material that is applied with the primary purpose of stopping the absorption
of succeeding coats.
A combination of a sealer, generally varnish, with wax.  Both the sealer and wax are normally
burnished to enhance wear and appearance.  Water spots and stains easily, but is simple to
repair.  Dries to tack free in 6-8 hours, reaching full cure in 7-14 days.
Any finishing material that is applied with the primary purpose of stopping the absorption of
succeeding coats.
SeparationThe breaking up or segregation of two or more integral parts of a mixture into its component parts.
In a varnish, this may take the form of the resin becoming insoluble in the other ingredients.
In a paint or enamel, it may mean that a clear liquid portion forms above the pigmented portion.
In liquid, there may be a segregation of layers of component liquids.
Setting The Separation of a pigment or other solid ingredient from a coating material upon standing.
Shade The degree to a color, as a dark green. Also , the act of changing the tone or degree of a color
by adding small quantities of other colors to it.
Shake A separation along the grain, the greater part of which occurs between and within rings or annual
Sheathing The structural covering, usually boards of plywood, placed over exterior studding or rafters of a structure.
Sheen The degree of luster of the dried film of a finishing material. It is usually used to describe the luster of
rubbed surfaces or of flat-drying materials.
Shellac A finish produced from a combination of alcohol and resins excreted by the Lac Beetle. Has good ambering,
may become tacky when subjected to high humidity and lacks the high abrasion resistance of more modern
finishes. Generally low in cost, this finish may water spot but is easy to use. Dries to tack free in 24 hours,
reaching full cure in 30 days.
 In tongue-and-groove strip and plank flooring, the individual pieces have a tongue milled on one side and
a groove milled on the opposite side, so that when the individual strips or planks are placed side by side, the
tongue of one piece fits into the groove of the next piece. See End-Matched and Tongue and Groove.
Skin  The film of oxidized or polymerized material that forms on the surface of adhesives and finishes while in a
container or tank.
Skippy thin or thins occurs when the flooring does not properly dress smooth due to thin lumber.
Slats See Fillets.
Sleeper Another name for screeds.
 A spline or small strip of wood or metal used to reverse or change direction in installing standard
tongue-and-groove strip flooring.  Positioning the slip-tongue into the groove side of the wood creates a
tongue. It is sometimes used in laying 3/4-inch (19mm) solid tongue-and-groove parquet.
Soft rot is a later stage of decay in which structural damage to the wood has occurred.
Softwoods General term used to describe lumber produced from needle and/or cone-bearing trees (conifers).
Solid Flooring manufactured from a solid piece of wood.
Group 1
A designation of a certain species based on density, strength and stiffness. Fir, pine and larch are such species.
 A sound knot is a knot that is solid across its face, at least as hard as the surrounding wood, and shows no
loose pieces or indication of decay.
 Sound rot is an early state of decay in which the decay has not effected the structural integrity of the wood.
Wood free from any form of decay, cracks or splits.
Species   Many species of wood have unique physical, mechanical or chemical properties. Species should be matched
to use requirements through an understanding of their properties. This requires identification of species in
wood form, independent of bark, foliage and other characteristics of the tree.  Identification can generally
be made on a basis of readily visible characteristics such as color, odor, knots and grain patterns.
Splits   A separation of the fibers along the grain forming a crack or fissure that often extends through the piece
from one surface to another.

End Split – A split at the end of a log, board or other wood product.  Often extension of end checks.
Springwood During the winter there is a dormant period when growth ceases. The absorption of large quantities of
moisture by the tree during the spring results in rapid growth, or the formation of wood cells with large
cavities and thin walls. The layer of wood cells put on by the tree during the spring is called “springwood”
and is usually darker in appearance then the surrounding “summerwood”. The difference in color is often
referred to as the “growth ring”.
Square-edge Flooring that isn’t tongue-and-grooved. May also refer to square-edge strip flooring that is face-nailed when
installed. Term may define lack of any edge treatment on any tongue and groove product.
Squares Parquet flooring units, usually composed of slats bound together in some format or shape.
Stain A discoloration in wood that may be caused by microorganisms, metal or chemicals. The term also applies
to materials used to impart color to wood.

Blue – (Sap Stain)  A bluish or grayish discoloration in the sapwood caused by the growth of certain
dark-colored fungi.

Brown – A rich, brown to deep-chocolate-brown discoloration of the sapwood of some pines caused by a
fungus that acts much like the blue-stain fungus.

Chemical – A general term including all stains that are due to color changes of the chemicals normally
present in the wood.

Chemical Brown – (Brown Oxidation Stain, Kiln Brown Stain, Yard Brown Stain, Kiln Burn, Coffee Stain
)  A brownish discoloration of chemical origin in wood that sometimes occurs during the air drying or
kiln drying of several softwood species, apparently caused by the concentration and oxidation of extractive.

Iron-Tannate – A surface stain, bluish-black in color, on oak and other tannin-bearing woods following
contact of the wet wood with iron, or with water in which iron is dissolved.
Stained sapwood is where the sapwood portion of the trunk has been exposed to some condition that has
caused a slight discoloration. This discoloration may be light gray, splotchy and/or dark.
The horizonal board which forms the ” walking” portion of the set of stairs.
A discoloration caused by fungi and/or chemical reaction associated with the location of the stacking stick.
Often called stick or sticker stain.
Sticker   A wooded strip, or its substitute, placed between courses of lumber or other wood product, in a pile, unit
package or kiln truck load, at right angles to the long axis of the stock, to permit air to circulate between
the layers. (Crosser Strip, Piling Strip, Stick)

Marking – Indentation or compression of the lumber or other wood product by the sticker when the
superimposed load is too great for the sticker bearing area. Also, sometimes identified as the discoloration
caused by blue stain or chemical brown stain in the wood at the location of the sticker.
(Crosser Stain, Stick Stain)
Sticker Stain Stained discolorations about 1″ – 2″ wide occurring across the width of a strip/plank and spaced corresponding
to sticker placement.
A mineral streak is an olive to greenish-black (in Maple) to light brown black (in Oak) discoloration of
undetermined cause in hardwoods. May be caused by an accumulation of mineral matter.
A general term often used for solid board flooring of less than 3″ in width to be installed in parallel rows.
Produced in these thicknesses; 5/16″, 3/8″, 1/2″, 3/4″and 33/32″ and these widths; 1-1/2″, 2″ and 2-1/4″. 
The strips are tongue and grooved and end matched. They are for nail down installation directly to wood
or plywood subfloor or screeds (sleepers).  Term may be used to define a width only.
Stud One of a series of slender wood structural members used as supporting elements in walls and partitions.
Summerwood  The portion of annual growth that is formed after the springwood. The cells formed during this period
have thicker walls and small cavities than those formed in the spring.
Surface The outside or exterior boundary of any substance. One is said to surface the work when it is rubbed or sanded
to a smooth, level plane.
When a coating dries on top, but remains relatively soft on the bottom, It’s said to surface dry.
The inherent molecular attraction in liquids that causes them to diminish their surface area and thereby exhibit
properties resembling those of a stretched elastic membrane.
An acid curing conversion varnish that is very stain, water and spot resistant. Ambers little, but during curing
may contain fumes that are harmful to plants and pets. Dries to tack free in 8-24 hours, reaching full cure in
14 days. Sometimes inaccurately defined as a urethane finish with wax applied.
The condition when a film of  finishing material has reached  the point that the surface can be can be touched
lightly without a sensation of stickiness.
Used to remove dust after sanding. May be used dry or with an appropriate liquid compatible with the finish to
be used.
A record of lumber volume giving the number of boards or pieces by size and often includes grade and species.
The ability of a film to withstand pulling stresses.
s of Film
The body on the work after the film of finishing material has thoroughly dried.
A check with a imperceptible or slight opening.
A tight knot is a knot so fixed by growth or position that it will firmly retain its place in the piece.
Tint A color produced by the addition of another color to white paint or enamel.
The act of adding the color to the white material is known as tinting.
A white pigment used in paints and enamels primarily to increase hiding power and give greater brightness.
It has a specific gravity of 3.0 and a relatively high oil absorption, which usually ranges from 20 to 26.
The particle size is usually very small.
In strip, plank and parquet flooring, a tongue is milled on one edge and a groove on the opposite edge.
As the flooring is installed the tongue of each strip or unit is engaged with the groove of the adjacent strip
or unit.
Torn grain consists of small pieces of the wood being torn out in surfacing.

A traditional finish is a smooth face without scraping, distressing, or other textures..
Within traditional finish there can be unfilled, semi-filled, and filled. Unfilled and semi-filled hardwood has
little or no filler used under the urethane finish in the graining during the manufacturing process.
A filled hardwood will have a completely smooth finish and feel where the graining has a filler applied to
achieve the smooth, level surface.
A tree grows in size as a result of new wood cells being developed in the cambium layer.
Tyloses In wood anatomy, froth-like growth in the pores of some hardwoods, notable in white oak and black locust.
Ultraviolet Light rays that are outside the visible spectrum at its violet end.  These rays have a chemical effect upon the
dried film of finishing materials.  Ultraviolet light is commonly used in curing finished at the factory for
prefinished flooring.  Ultraviolet light also causes woods to lighten or darken.
Undercoats Coats that are applied prior the finishing or final coats.
Unfinished A product that must have a finish and/or stain applied after installation.
Defects with a large opening, excessive movement, or an excessively soft area.
A synthetic chemical structure formed by one of three specific chemical reactions.
UV Lines
Lines in the urethane finish usually caused by cuts in the roller.  
Polyurethane that cures due to the activity of photo initiators which become excited by UV lights.
Veneer   Thin sheets of wood which plywood is made. Also referred to as “plies” in the glued panel.
Varnish   A finish that contains either natural or synthetic oils that are refined by boiling and cooking with
the addition of dryers. Slow to cure, but can be accelerated by the addition of heat. When used as a sealer,
it is often burnished with a buffer and pads, the friction of which accelerates the curing process. Ambers well,
somewhat stain and spot resistant, but may be scratched easily when new due to slow curing time.
Dries to tack free in 24-28 hours, reaching full cure in 30-60 days.
Wane Bark, or the lack of wood from any cause, on any edge of square-edge lumber.
Warping Any distortion of a piece of flooring from its true plane.
A waterborne urethane that is fully cured and dries by water evaporation.  See Polyurethane.
Water Borne
This large family of finishes has a common trait of having the solids suspended in water which is used as the
solvent. A clear, color free finish available as a one part, cross linked or as a two-part. Products using a
cross-linker (catalyst) may have enhanced stain and abrasion resistance. Easy to apply with low odor and
good stain resistance, but may raise grain during first and second coat. Fast drying and easy to recoat.
Dries to tack free in 24 hours, reaching full cure in 14 days.
White Oak   Color – Heartwood may vary from greenish tan to brown; some boards may have a pinkish tint or slight grayish
cast.  Sapwood is white to cream. Grain – Open with longer rays than red oak.   Plain sawn boards have a plumed
or flared grain appearance; quarter sawn has a flake pattern.
Wiping Stain Those stains, usually pigmented, that are applied then wiped with a cloth to remove excess.
A method for imparting an artificial texture or distressed appearance to the surface of hardwood flooring.
Wood   The tissues of the stem, branches and roots of a woody plant lying between the pith and cambium, serving for
water conduction, mechanical strength, and
food storage and characterized by the presence of tracheids or vessels.
Flooring is produced from trees which are living plants, and having a general knowledge of tree growth and
wood structure is desirable and necessary.

Worm holes are holes caused or made by a wood boring insect.  
Updated on September 22, 2022