| Gloss | The amount of shine on a finished board or reflecting ability of surface. |
| Gloss Meter | An instrument for measuring the luster or gloss of a finished surface. |
| Glossing Up | The increase of luster in a rubbed film through friction in use or the increase in luster of a flat varnish in the package through a decrease in the effect of a flattening agent. |
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Gouge | A groove or cavity in the flooring surface accompanied by material removal and penetration below the immediate flooring surface. |
| Grade | The designation of the quality of a manufactured piece of wood or of logs. |
| Grading Rules | Specifications or guides for classifying wood or manufactured pieces according to quality or use. |
| Grain | The direction, size, arrangement, appearance or quality of the fibers in wood or lumber. To have a specific meaning the term must be qualified. Edge Grain – (Quarter Sawn) Wood that has been sawed so that the wide surfaces extend approximately at right angles to the annual growth rings. Wood is considered edge grained when the rings form an angle of 45 degrees to 90 degrees with the wide surface of the piece. See Vertical Grain. Flat Grain – (Flat Sawn, Plain Grain, Plain Sawed, Slash Grain, Tangential Cut) Wood products sawed parallel to the pith and approximately tangent to the growth rings. Wood is considered flat grained when the annual growth rings make an angle of less than 45 degrees with the surface of the piece. Open Grain – Common classification for woods with large pores, such as oak, ash, chestnut and walnut. Also known as “coarse textured”. Torn Grain – Wood products in which fibers are torn out below the finished surface, particularly around knots and curly places, by the action of planer knives. Vertical Grain – Wood that has been sawed so that the wide surfaces extend approximately at right angles to the annual growth rings. Wood is considered edge grained when the rings form an angle of 45 degrees to 90 degrees with the wide surface of the piece. |
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Graininess | The appearance of small, grain-like particles in a finishing or in the dried film thereof. |
| Grub Worm Holes | Grub worm holes can be up to a 1/2″ in diameter. |
| Hardness | That property of the wood species or dried film of finishing material that causes it to withstand denting or being marked when pressure is exerted on its surface by an outside object or force. |
| Hardwoods | Generally one of the botanical groups of trees that have broad leaves in contrast to the conifers or softwood.The term has no reference to the actual hardness of the wood. |
| HartWood | The top ply treatment of products that are acrylic impregnated without a top coat. |
| Heartwood | The inner layer of a woody stem wholly composed of nonliving cells and usually differentiated from the outer enveloping layer (sapwood) by its darker color. Heartwood is the support structure for the living tree. It is usually more decay resistant than sapwood. |
| Heavy Streaks | Spots and streaks of sufficient size and density to severely affect the appearance of the wood. |
| High Solids | A general term used to denote the presence of a higher than average percentage of solid ingredients and thus a lower percentage of solvents. |
| Holes | Openings in or through lumber that may extend partially or entirely through a piece and may be from any cause. Holes extending partially through a piece are often termed surface pits. The size of a hole is the average to its maximum and minimum surface diameters unless otherwise specified. |
| Hollowback | The grooves, usually two, that run length-wise down the back of flooring. |
| Honeycombing | In lumber and other wood products separation of the fibers in the interior of the piece, usually along the wood rays. Honeycombing is often not visible on the surface, although it can be the extensions of surface and end checks. Generally caused seasoning. (Hollow Horning, Internal Checking, Interior Checking, Inner Checking). |
| Humidity | The amount of water vapor in the air. See Relative Humidity |
| Hygrometer | An instrument for measuring the degree of humidity or relative humidity of the atmosphere. |
| Hygroscopic | A substance that can absorb and retain moisture, or lose or throw off moisture. Wood and wood products are hygroscopic. They expand with absorption of moisture and their dimensions become smaller when moisture is lost or thrown off. |
| Impact Test | A test for determining the resistance to shattering of a dried film by dropping a weight onto the finish. |
| Incipient Decay | The early stage of decay that has not proceeded far enough to soften or otherwise perceptibly impair the hardness of the wood. |
| Intensity | The intensity of a color is its purity or degree of hue as seen by the eye. |
| Jointed Flooring | Strip flooring, generally birch, beech, hard maple or pecan, manufactured with square edges, not side-matched, but usually end-matched. It is used principally for factory floors where the square edges make replacement of strips easier. |
| Joist | One of a series of parallel beams used to support floor or ceiling loads and supported in turn by larger beams, girders or bearing walls. |
| Juvenile Wood | The initial wood formed adjacent to the pith, characterized often by lower specific gravity, lower strength, higher longitudinal shrinkage, and different micro-structure than mature wood. The amount of juvenile wood may vary from tree-to-tree and may extend from the pith to between 5 to 20 growth rings from the pith. |
| Kiln | A chamber or tunnel used for drying and conditioning lumber, veneer, and other wood products in which the temperature and relative humidity of the circulated air can be varied and controlled, often steam heated and vented. Charge – In kiln drying, the total amount of lumber or wood items to be dried in a dry kiln. Dried – Lumber or other wood items that were dried in a closed chamber in which temperature and relative humidity of the circulated air can be controlled. |
| Kinks | Kinks are an abrupt offset in the edge surface that usually occurs near the ends of the piece. |
| Knife Marks | A series of surface imprints or markings made by the machine knives in dressed lumber. |
| Knot | That portion of a branch or limb which has been surrounded by subsequent growth of the wood of the trunk or other portions of the tree. A knot appears on the sawed surface, it is merely a section of the entire knot, its shape depending upon the direction of the cut. Cluster – Three or more knots in a compact, roughly circular group, with the grain between them highly contorted, originating from adventitious buds. Decayed Knots – A knot that, due to advanced decay, is softer than the surrounding wood. Encased Knot – A knot whose rings of annual growth are not inter-grown with those of the surrounding wood. Firm Knot – A knot which is solid across its face, but which contains incipient decay. Fixed Knot – A knot which will hold its place in dry lumber under ordinary conditions, but can be moved under pressure although not easily pushed out. Hole – A hole previously occupied by a knot. Inter-grown Knot – A knot whose rings or annual growth are completely inter-grown with those of the surrounding wood. Loose Knot – A knot that is not held firmly in place by growth or position and that cannot be relied upon to remain in place. Sound Knot – A knot that is solid across its face, at least as hard as the surrounding wood, and shows no indication of decay. Spike Knot – (Horn knot, Mule-ear knot, Slash knot) A knot cut approximately parallel to its long axis, so that the exposed section is definitely elongated. Tight Knot – A knot so fixed by growth or position that it will firmly retain its place in the piece. |
| Knot Hole | Knot hole is a hole previously occupied by a knot. |
| Lacquer | A finish containing nitrocellulose, more often used as a sealer. The fast curing properties of this finish are created by using a solvent with a very low flash point which causes it to be very flammable. Ambers little, cures rapidly, but may water spot and become cloudy when applied in high humidity. Can be incompatible with some types of stains and topcoats. Dries to tack free in 10-30 minutes, reaching full cure in 4-8 hours. |
| Lap | Used as a verb, lap means to lay or place one coat so its edge extends over and covers the edge of a previous coat, causing an increased thickness where the two coats are present, as compared to the single thickness on either side of the lap. As a noun, lap is that portion of a coat of finishing material that extends over the edge of and onto a previous coat. |
| Late Wood | The portion of the annual growth ring that is found after the early wood formation has ceased. It is usually denser and stronger than early wood (Summerwood). |
| Leveling | The ability of a film to flow out free of ripples, pock marks, brush marks or other surface defects. |
| Loosened Grain | The separation of the growth ring, primarily at the tips, from the surface of a wood slit, especially on the surface of plainsawn wood. |
| Lumber | The product of the sawmill and planing mill not further manufactured than by sawing, re-sawing, passing lengthwise through a standard planing machine, cross cutting to length and matching. Flooring Lumber – Generally, a grade of either hardwood or softwood boards that have been found to produce maximum quantity of flooring of the desired quality. |
| Machine Burn | A darkened area across the width of flooring caused by a machine. |
| Manufacturing Characteristics | Manufacturing characteristics described below include: Scant thickness, Saw marks, Skippy thin, Raised grain, Wavy face, Torn grain, Mismatched pieces, Kinks, Planer bite, Off square end matching, Machine burns, Rub marks, Rough handling, Edge deflects, Broken corners and Wane. |
| Medullary Rays | Strips of cells extending radially within a tree and varying in height from a few cells in some species to four or more inches in oak. The rays serve primarily to store food and transport it horizontally in a tree. On quarter sawn oak, the rays form a conspicuous figure, sometimes referred to as Flecks. |
| Meter | Electronic Moisture Meter – An instrument used for rapid determination of the moisture content in wood by electrical means. Capacitance Type Electric Moisture Meter – A meter for determining the moisture content of wood by utilizing the variation in the dielectric constant of wood with changing moisture conditions. R. F. Power Loss Type Electric Moisture Meter – A meter for determining the moisture content of wood by utilizing the variation in the wood dielectric loss factor with changing moisture content. Resistance Type Electric Moisture Meter – A meter for determining the moisture content of wood by utilizing the variation in wood electrical resistance with changing moisture content. |
| Mineral Spirits | A solvent product used as a thinner and/or cleaner. Often known generically as “paint thinner”. |
| Mineral Streak | An olive to greenish-black or brown discoloration of undetermined cause in hardwoods, particularly hard maples, which occurs in streaks usually containing accumulations of mineral matter. |
| Mixed Media | A wood floor that is predominately of wood, but also incorporates other materials, such as slate, stone, ceramic, marble or metal. |
| Moisture Content | The amount of water contained in the wood, usually expressed as a percentage of the weight of the over dry wood. NWFA hardwood flooring is manufactured at 6% to 9% Moisture Content, with a 5% allowance for pieces up to 12% Moisture Content. Average Moisture Content – The moisture content, in percent, of a single section representative of a larger piece of wood or the average of all the moisture content determinations made on a board or other wood item or of a number of determinations made on a lot of lumber or other wood products. An oil based varnish enhanced with urethane. This hybrid ambers well and has good abrasion resistance. Curing may be delayed when humidity levels are high, which can lead to inadvertent damage such as scratches. Very stain and abrasion resistant, but has a long curing time. Dries to tack free in 8-36 hours, reaching full cure in 30-60 days. Kiln Dried Moisture Content – The moisture content of wood that has been dried in a kiln; usually from 6% to 9% for thoroughly kiln dried stock. |
| Moisture-Cured Urethane | As the name implies, this finish cures in the presence of moisture and fails to do so in its absence of strongly ambering or available in non-ambering. Very stain, spot and water resistant, but requires very tight environmental control during application and curing. May cure too rapidly and flatten poorly when applied in very high humidity. Long delays in curing may occur in areas when humidity levels are quite low. The excellent abrasion resistance also makes this finish difficult to recoat. Dries to tack free in 8-24 hours, reaching full cure in 14-30 days. |
| Mold | A fungus growth on lumber or other wood products at or near the surface and, therefore, not typically resulting in deep discolorations. Mold is usually ash green to deep green in color, although black and yellow are common. |
| Mosaic Parquet | See Parquet. |
| Muratic Acid | A diluted acid used to neutralize alkalinity of concrete subfloors. |
| Narrow Groove | Rough edge where the board is not wide enough to machine smooth on the groove side. |
| Natural Growth Characteristics | The tree from which lumber and flooring is obtained is a product of the soil, moisture, air and sunshine in constantly varying combinations. Throughout its life the tree is subjected to extremes of heat and cold, flood and drought and has been buffeted by countless storms. As a result, wood is extremely variable in structure and appearance. Along with this variability in structure and appearance, certain characteristics occur in the wood because of the growing conditions and injuries. In addition, further characteristics develop through the process of manufacturing and drying. |
| Nominal Size | As applied to timber or lumber, the size by which it is known and sold in the market, often different from actual size. |
| Nosing | The rounded and projecting edges of the treads of a stair or the edge of a landing. Usually where these edges are right-angled, in resilient floor installations, they are protected by a slightly rounded metal edging, also called “nosings” |
| Off Square | Any end that is not 90 degrees to the edge. |
| Oil-Modified Urethane | An oil based varnish enhanced with urethane. This hybrid ambers well and has good abrasion resistance. Curing may be delayed when humidity levels are high, which can lead to inadvertent damage such as scratches. Very stain and abrasion resistant, but has a long curing time. Dries to tack free in 8-36 hours, reaching full cure in 30-60 days. |
| Open Grain | A failure of finish to form a film over areas of low density, normally associated with the softer spring wood. The finish is absorbed into the softer grain failing to form a film and causing a loss of sheen. While not considered a finish defect, it can often be concealed by the application of an additional coat of finish. |
| Orange Peel | A finish that exhibits a surface texture resembling the surface of an orange. Normally caused by rolling a finish that has cured excessively which freezes the roller pattern in the film. May also be caused by excessive air flow, the velocity of which freezes waves in the film when it sets. |
| Out of Match | Out of match flooring consists of pieces in which the surface of adjoining pieces are not in the same plane. |
| Overwood | This term applies to two pieces of hardwood (usually square edge) where the surface of one piece is higher than the next. |
| Parquet | A floor of any non-linear pattern. Generally a tile composed of individual slats assembled together. A square may or may not possess tongues and grooves to interlock and isn’t necessarily square or regular in dimension. |
| Peeling | A defect in a dried film manifested by large pieces becoming detached from the under surface and coming loose in sheets or large flakes. |
| Penetrating Stains | Stains that penetrate into the surface of the wood. They are usually made of dyes dissolved into liquids that easily penetrate the wood. |
| Permion Finish | An integrated system of coating and coloring designed for the commercial market. An ultraviolet cured urethane topcoat with aluminum and mineral oxide additives incorporated in the urethane. The oxides increase wearability of the urethane finishes. |
| Petroleum Spirits | Another word for mineral spirits. |
| pH Value | The concentration of the hydrogen ion in a material. A pH value of 7 is considered neutral. Lower values are acidic; higher values are alkaline. |
| Photo-sensitive | The property of some wood species which causes them to lighten or darken when exposed to light. |
| Pigment | The fine, solid particles used for color or other properties in the manufacture of paint and enamel. |
| Pigment Stains | Stains that get their color primarily from pigments mixed with binder and volatile thinners. |
| Pinholes, Pin Lines | Normally caused by finish flowing into low lying or less dense areas such as springwood. This thicker film of finish allows gasses formed during curing to freeze in the film leaving a small crater. The finish fails to form a film in these areas as the finish is in the wood instead of on it. While not considered a finish defect, it can be corrected by the application of an additional coat of finish. |
| Pin Worm Hole | In hardwood flooring, a small round hole not over 1/16″ in diameter, made by a small wood boring insect in the living tree. Allowed in all grades. |
| Pith | The small, soft core occurring near the center of a tree trunk, branch, twig or log. |
| Plain Sawn | Lumber that has been sawed approximately tangent to the growth rings. Lumber is considered plain sawn (flat grained) when the annual growth rings form an angle of 45 degrees or less with the wide surface of the piece. |
| Planer Bite | A groove cut in the surface of the face or edge of a slat, cut deeper than intended by the planer knives. |
| Plank | Solid boards, usually 3/4″ thick and 3″ to 8″ wide designed to be installed in parallel rows. Edges may be beveled to simulate the appearance of Colonial American plank floors. |
| Plugs | Dowels that simulate the Colonial American plugged or pegged plank look. They are used to cover countersunk screws when installing wood flooring or for decorative purposes in wood flooring. |
| Polyurethane | A large molecule of chemically joined urethane units, having the capacity to solidify or “set “. Irreversible when acted upon by heat, radiation or chemical crosslinking or curing agents. See Urethane. |
| Powderpost Beetles | Beetles which derive their common name from the small piles of powder-like frass ejected from holes bored when the mature insect takes flight. Destroyed in kiln drying through heat sterilization, but may reinvest dry lumber. |
| Prefinished | A completely finished flooring that required installation only. |
| Puckering | The crinkling, shriveling or wrinkling of a coat of finishing material upon drying. |
| Pure | Free of adulteration. |
| Quantity | The amount, bulk, mass, weight or measure of a thing; a measure of its size or numbers. |
| Quarter Sawn | Lumber that has been sawed so that the wide surface is approximately at right angles to the annual growth rings. Lumber is considered quarter sawn (edge-grained) when the rings form an angle of 45 degrees to 90 degrees with the wide surface of the piece. |
| Raised Grain | A condition when dense summerwood is raised above the springwood on the surface of a slat but not torn loose. Usually caused by absorption of moisture. |
| Ray | In wood anatomy, a ribbon-like aggregate of cells extending radially across the grain, so oriented that the face of the ribbon is exposed as a fleck on the quartered surface. See Medullary Rays. |
| Red Oak | Color – Heartwood and sapwood are similar, with sapwood lighter in color; most pieces have a reddish tone. Slightly redder than white oak. Grain – Open, slightly coarser (more porous) than white oak. Plain sawn boards have a plumed or flared grain appearance; quarter sawn has a flake pattern. |
| Reduce | To lower the viscosity of a material or to thin it by the addition of a solvent, thinner, varnish, oil, etc. |
| Refinished | Sanding a previously finished floor to bare wood and applying new finish. |
| Relative Humidity | Ratio of the amount of water vapor present in the air to that which the air would hold at saturation at the same temperature. It is usually considered on the basis of the weight of the vapor, but for accuracy should be considered on the basis of vapor pressures. |
| Retarder | A slowly evaporating solvent that decreases the evaporation rate or slows up the drying of lacquers and similar materials. |
| Rift Sawn | Lumber (primarily hardwoods) in which the annual rings make angles of 30 degrees to 60 degrees with the surface of the piece. Also known as bastard sawn. |
| Ring- Porous Woods | A group of hardwoods in which the pores are comparatively large at the beginning of each annual growth ring and decrease in size, more or less abruptly, toward the outer portion of the annual growth ring. The large pores are springwood and the smaller pores are summerwood. |
| 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. |
| Rough Handling | In stacking wood items such as lumber or dimension stock for drying, or in the take-down of piles, unit packages in kiln trucks, the breakage, splitting, gouging, tearing or general value loss due to carelessness in moving the pieces, or damage caused by maladjusted mechanical equipment. |