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Wood finishing Terms

Acetate- A fast-evaporating solvent found in lacquer thinner and in solvent refinishers used to strip lacquer, shellac, and other old finishes.

Acrylic- A synthetic resin found in water-based paints.

Alkyd- A synthetic resin that is steadily replacing linseed oil in oil-based paints.

Alligatoring- Cracks spread over the surface of a finish, often caused by inflexibility of an older finish, too much finish, or a reaction between two coats of finish.

Aluminum Oxide- An abrasive used on high-quality sandpaper.

Aniline Dye- A synthetic tinting agent that can be dissolved in denatured alcohol, mineral spirits, or water. More translucent than heavily pigmented stains, it is preferred by many professional woodworkers who have learned how to handle its fast-acting, permanent colouring.

Backing- The paper or cloth to which abrasive particles are attached to form sandpaper.

Benzene- A highly flammable solvent also used as a cleaning fluid. Also called naphtha.

Binders- the resins that form the dried surface film of a finish.

Bird's-Eye- Small, circular imperfection found most often in maple; heavily favored by professional woodworkers for its unique beauty.

Bleeding- A finishing defect occurring when the previous layer of paint or stain seeps through the topcoat.

Blistering- A paint failure often caused by moisture in the wood breaking the bond between the paint and the wood.

Bloom- A temporary or permanent finish failure characterized by a whitish cast; often associated with shellac or lacquer.

Bristle- Refers to either natural or synthetic filaments.

Brush Marks- Lines or ridges left by the brush and dried in a finish.

Burl Veneer- Thin, brittle sheets of wood, most often walnut or elm, sliced from a warty growth on a tree; characterized by a swirling, highly figured grain.

Burn-in Stick- Coloured wax, shellac, or lacquer that is melted into a gouge in the wood, allowed to cool, then sanded or trimmed with a sharp blade.

Butt Joint- An easy but often weak technique for joining two boards together by gluing and pressing the flat surfaces together.

Carnauba- A South American palm tree noted for production of a high-quality wax.

Caustic Soda- Commonly known as lye, a very dangerous chemical when mixed with water in strong solutions; formerly used in homemade paint-stripping formulas.

Chalking- A gritty, chalklike film of pigments released by some exterior house paints as they weather.

Chemical Stains- A means of colouring wood using the semi-predictable reaction between certain woods and various chemicals; fuming, in which oak is exposed to ammonia fumes or liquid, is a well-known example.

China Wood Oil- Another name for tung oil, which originated in the Far East where the seeds or nuts of the tung tree were pressed to extract an oil valued for its finishing qualities.

Closed-Coat Sandpaper- Sandpaper designed with virtually no spaces between the cutting particles; the larger number of abrasive particles cut very quickly but clog easily.

Closed-Grain- Wood, such as maple, pine, and poplar, without a distinct pattern of pores; unlike open-grain woods, such as oak and mahogany, closed-grain woods do not require filling to achieve a smooth finish. Also called closed-pore.

Crazing- Similar to alligatoring, but the tiny cracks in the surface of the finish are not as deep, as distracting, or as threatening to the wood; in antiques, crazing is often indicative of a prized original finish.

Cut- A means of measuring the proportion of shellac flakes dissolved in denatured alcohol. Most premixed cans of liquid shellac are a 3-pound cut (i.e., 3 pounds of shellac dissolved in 1 gallon of solvent).

Danish Oil- A penetrating oil finish often produced using boiled linseed oil, driers, resins, and solvents.

Denatured Alcohol- Ethyl alcohol made toxic by the addition of poisonous liquids; used as a solvent for shellac.

Distressing - Imitating the aging process of wood by imparting marks or colorants to the wood or finish.

Dovetail- A widely used and respected technique for joining two boards, in which alternating slots and protrusions (resembling a bird's tail) are snugly fitted together, increasing the gluing surface and producing a joint that, even without glue, can be difficult to pull apart.

Driers- Chemicals that decrease the drying time of a finish. Often called a japan drier.

Drying Oils- Penetrating oils that transform into solids when they come in contact with oxygen; tung oil and linseed oil are two common drying oils.

Emery- A naturally occurring, extremely hard mineral applied to cloth backing to produce a fine sand paper.

End Grain- The wood surface exposed when a board is cut across the grain, opening the elongated pores so that they absorb more liquid than the other parts of the board.

Escutcheon- The small wooden or metal decorative plate applied over the keyhole in a door or drawer.

Ferrule- The metal band used to hold the bristles to the handle of a brush.

Figure- The decorative elements in the grain pattern of a board produced by rays, pores, knots, and colours; a board such as quartersawn oak is said to be "highly figured".

Filament- A slender synthetic fiber or natural hair utilized as the bristle in a brush.

Filler Stick- Generally a coloured, wax-based stick used to fill nail holes or small cracks in a finished board.

Filling- The technique employed to force, with a rag or brush, a semi-liquid material into the open pores of a board to help produce a smooth surface. Also called a paste filling.

Fish Eyes- Small craters in a finish, generally produced by a contaminant on the surface to which the finish will not adhere, such as silicone, oil, or wax.

Flagging Tips of bristles that have been intentionally split to carry more liquid from the can to the wood.

Flaking- A finish failure, wherein the top layer of finish loses its bond with the previous layer or the wood.

Flat- A low-gloss finish.

Flat-Grain Wood- The long, wavy grain pattern found on boards produced by simply slicing the log from one end to the other; this is the most common method of producing lumber. Also called plain-sawn.

Flattening Agent- A finish additive that reduces the gloss; if over-used, it can weaken the finish.

Flint- A natural mineral abrasive used in the manufacture of low- to medium-quality sandpaper.

Flitch- A stack of boards or sheets of veneer sawn from the same log and remaining in the order in which they were cut.

Foam Brush- An inexpensive, disposable brush in which a tapered piece of foam replaces the bristles.

French Polishing- A highly technical, labor-intensive, slow-building process of applying thinned shellac with a special pad; most often associated with fine European antiques.

Fuming- A method by which the colour of woods containing tannin, such as oak and chestnut, can be altered by exposing them to the fumes of 26 percent ammonia.

Garnet- A natural mineral abrasive used in the manufacture of high-quality sand paper.

Glaze- A transparent to translucent finish designed more for decorative effects rather than durability.

Glides- Metal, nylon, plastic, or carpeted discs attached by means of a built-in tack or nail to the bottoms of chairs, tables and other furniture.

Gloss- The sheen of a finish, either flat, satin, semi-gloss, or high gloss.

Grain- The longitudinal pattern created by the arrangement of the pores and wood fibers; most wood-finishing techniques follow the direction of the grain to avoid unsightly cross-grain marks.

Graining- A technique that uses paint to imitate the grain of various woods.

Grain Raising- When wood fibers absorb liquids, those on the surface of the wood swell, leaving the wood feeling rough to the touch; water is the most common grain-raising liquid. Woodworkers will intentionally dampen a board prior to final sanding to remove loose fibers, which otherwise would have swollen when the finish was applied.

Grit- The numbering system that reflects the relative coarseness of the abrasive particles on sandpaper. Lower grit numbers indicate coarse abrasives; higher grit numbers, finer abrasives.

Ground Coat- The initial or base coat of two-part decorative painting and graining techniques.

Hardwood- Generally speaking, wood harvested from broad-leafed trees.

Heartwood- The oldest, hardest most decay-resistant portion of a log. Namely, the center.

Holidays- A professional painter's term for bare spots devoid of any paint or finish; also called skips.

Hue- Another name for tint or colour

Japan Colours- Tinted pigments that can be diluted with either oil-based or lacquer-compatible products.

Japan Drier- A blend of driers and solvents designed to increase the drying time of oil-based finishes.

Knot- A round or oval imperfection in a board created by the growth of a limb at that point. If not properly sealed, can cause problems in the staining and finishing stages.

Kraft Paper- An inexpensive, brownish paper used for grocery bags, containers, drop cloths, and paint masking.

Lac- A natural resin deposited on branches by the lac insect, it is harvested and refined into shellac.

Lacquer- A durable, fast-drying finish developed during World War II and favored by the commercial furniture industry; generally is sprayed, although brushing lacquers are available.

Latex- A water-based paint

Latex Stain- A water-based stain

Leveling- The "flowing out" of a freshly applied finish, during which brush marks disappear.

Linseed Oil- A natural oil extracted from flaxseed; boiled linseed oil has had driers and solvents added to decrease the drying time.

Medullary Rays- The channels within certain trees that transport water between the heartwood and the bark; when these trees, most notably oak, are cut by the quartersawn method, the medullary rays are revealed as diagonal flakes highly regarded for their decorative effect.

Methylene Chloride- A chemical that attacks and dissolves most finishes; utilized in many paint and varnish remover formulas.

Mill Marks- Irregular, crushed, and sliced wood fibers caused by the machines that cut and smooth lumber.

Millwork- A large classification for any woodwork that is manufactured in lumber mills; includes moldings, picture rails, door trim, baseboard, and stairway parts.

Mineral Oil- A lightweight, natural oil used in many dusting products.

Mineral Spirits- A solvent refined from petroleum and used in oil-based formulas; is similar to paint thinner.

Miter- The woodworking joint created when two boards are cut at an angle to one another; the most common miter joint is the 45-degree miter used for picture frames.

Moisture Content- Measured in percentages, the relative amount of moisture in a board.

Mortise- An opening, drilled or chiseled into a board, such as a chair leg, to receive the end (called the tenon) of an intersecting board, such as a chair rung. Together they form a mortise-and-tenon joint.

Neoprene- An artificial rubber highly resistant to most solvents found in wood-finishing products.

Nitrocellulose- A complex formulation of acids and cotton cellulose that forms the basis for modern lacquer.

Oil Colours- Pigments mixed in a linseed oil base suitable for tinting oil-based products.

Open-Coat Sandpaper - Sandpaper designed with spaces between the abrasive particles; does not remove wood as quickly as closed-coat sandpaper; but does last longer.

Open-Grain- Woods, such as oak and mahogany, characterized by prominent, open pores that must be filled in order to achieve a smooth finish.

Orange Peel- A term used by professional finishers to describe a textured surface that occurs if the spraying equipment or mixture for lacquer is not correct.

Orange Shellac- Unbleached shellac that retains its natural amber hue.

Overspray- Finish, propelled by spray equipment that lands and dries on surfaces other than the target.

Oxidize- To react to oxygen.

Paraffin Oil- A lightweight mineral oil often used as a lubricant when rubbing out a finish.

Particleboard- Lumber manufactured from wood chips that have been glued and pressed together under heat.

Paste Filler- A thick, puttylike material intended to be thinned before spreading across the open pores of a board; after the excess is wiped off, the remaining filler dries in the pores before being sanded and finished.

Patina- The mellow glow that wood, metal, and wood finishes acquire after prolonged exposure to handling, dusting, and polishing.

Pegged Joint- A mortise-and-tendon joint that is strengthened by drilling a hole and inserting a length of dowel through both boards; also called a pinned joint.

Pigmented Oil Stain- A linseed oil-based stain that relies on pigments for its colour; since the excess is often removed with a cloth, it is referred to as a wiping stain.

Pigments- Naturally coloured minerals that are finely ground and suspended in a liquid.

Plain-Saw- The long, wavy grain pattern found on boards produced by simply slicing the log from one end to the other; the most common method of producing lumber. Also called flat-grain wood.

Polyurethane- A popular synthetic resin used to formulate tough varnishes.

Pores- Cell-like cavities that characterize the grain of the wood.

Primer- Paint designed more for its ability to bond with wood and other finishes than for its resistance to weather.

Quartersawn- Boards produced by first cutting the log into quarters and then slicing each quarter to reveal the medullary rays; noted for its strength and resistance to cupping in addition to its beauty.

Raised Grain- A condition of the wood caused when a liquid such as water forces the loose surface fibers to swell.

Rejuvenator- A number of solvents and combinations of solvents designed to partially or slowly dissolve and aid in the redistribution of an old shellac or lacquer finish.

Resin- An artificial or natural substance that forms a thin, hard, transparent shell on wood.

Retarders- Solvents noted for their increased drying time; occasionally added to paints or lacquers to lengthen drying time.

Rotary Cut- Veneer cut by spinning a log against a stationary blade to produce a continuous sheet; generally used for plywood.

Rottenstone- A natural abrasive ground from powdered limestone. It is finer than pumice and is often used in a second step when rubbing out a finish.

Rubbing Compound- A commercially prepared mixture of abrasive powder and lubricant that is used for a final rubbing of a finished surface; often sold in automotive supply stores.

Runs- A finish defect resulting from too much finish on a vertical or tilted surface.

Sapwood- The outside of a tree where active growth takes place; produces immature, lighter-coloured wood when milled.

Satin- A sheen considered more reflective than flat, but less so than semi-gloss.

Sealer- A finish designed to seal the pores of the wood, to dry quickly, and to sand easily in preparation for the final coats.

Shading Stain- Most often a lacquer finish to which dyes or pigments have been added; used extensively on mass-produced furniture.

Shim- A thin, wooden wedge.

Silicon Carbide- A hard, synthetic abrasive produced in an electric furnace and attached to waterproof backing for use as wet/dry sandpaper

Slicing- A means of producing veneer by driving a half-log or flitch against a pressure bar and knife while holding it against a metal bedplate. The shearing action produces very smooth surfaces, but the width of the veneer is determined by the width of the log.

Softwood- Generally speaking, wood produced by trees that have needles rather than broad leaves. The term has no direct relation to the actual hardness of the wood.

Solvent- Any liquid that can be used to dissolve other substances. The most common solvents in wood finishing are water, mineral spirits, denatured alcohol, acetone, turpentine, and toluene.

Spar Varnish- A durable varnish formulated for exterior use; it remains slightly softer and more flexible than interior varnish.

Spirit Stain- A wood stain dissolved in alcohol.

Spontaneous Combustion- Self-ignition resulting from unvented heat generated in a chemical reaction. Occurs most often with rags containing linseed oil, Danish oil, and tung oil.

Stain- Any of several solvents containing dyes, pigments, or chemicals used to add colour to wood.

Tack Cloth- A cloth saturated with a diluted finish to enable it to pick up dust.

Tannin- A natural acid found in certain woods, namely, oak and chestnut, that reacts to ammonia to change the colour of wood in the fuming process.

Tenon- The end of a board that is inserted into a mortise or opening in a second board; an exposed tenon passes entirely through the second board. (See also mortise.)

Tinting Colours- Pigments or dyes suspended in any of several solvents.

Tung Oil- A natural oil extracted from the seeds of the Chinese tung tree.

Turpentine- A natural solvent distilled from the gum of pine trees, and used in oil-based stains and finishes.

Universal Tinting Colours- Pigmented liquids compatible with oil-based and water-based products.

Varnish Stain- Varnish to which stain has been added; while the product reduces staining and finishing to one step, the stain lies on top of the wood rather than being absorbed by the wood.

Water-Emulsion Varnish- Another name for latex varnish, wherein the resins are suspended in water.

Water-Stain- Aniline dyes dissolved in water.

Water White- A term used to describe a perfectly clear, nonyellowing finish.

Wet/Dry Sandpaper- Silicon carbide particles attached to a waterproof backing; used for extremely fine sanding.

White Shellac- Shellac that has been bleached to remove its amber hue.

Wood Dough- A soft patching material that comes in a number of colours; unlike wood putty, it hardens and can be sanded smooth afterward, making it suitable for small- to medium-sized repairs on raw wood.

Wood Putty- A doughy product used to fill nail holes and small defects in wood.