GLOSSARY

K - glossary            (  L  :  M  :  N  :  O  :  P  )

KETONE SOLVENT
Organic solvent containing the CO grouping. Ketone solvents have relatively strong solubility parameters and exhibit strong hydrogen bonding and high polarity. Ketones used in paints include acetone (dimethyl ketone), methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK).

L - glossary

LAC
A natural resin secreted by insects that live on the sap of certain trees in Far Eastern countries. This resin is refined to make shellac.

LACQUER
A coating composition based on synthetic, thermoplastic, film-forming material dissolved in organic solvent that dries primarily by solvent evaporation.

LADDER HOOK
Steel hook shaped like an inverted U. One end attaches to the ladder and the other end hooks the ladder to a roof, pipe, or similar anchorage.

LADDER JACK
A metal support that attaches to an extension ladder. When used in pairs, ladder jacks may support a plank or lightweight stage placed across them to form a light-duty scaffold.

LADDER SHOE
A device mounted on the base of a ladder side rail to give stability and slip resistance to the ladder.

LADDER, HIGHEST STANDING LEVEL
The rung or step of a ladder above which the user should never climb for safety reasons.

LADDER, TYPES OF
(1) STEPLADDER—A self-supporting ladder of fixed height, which usually has flat, broad, level steps, a movable back frame hinged to the front legs, and a spreading device to hold the ladder open. (2) DOUBLE STEPLADDER—A stepladder with steps on both sides. (3) STRAIGHT LADDER—A non-self-supporting ladder of fixed length, consisting of two parallel sides, or rails, joined by rungs. (4) EXTENSION LADDER—A non-self-supporting ladder of adjustable length; it consists of two or three straight ladder sections that fit together so that the ladder length can be adjusted using a rope and pulley. (5) TRESTLE LADDER—A self-supporting ladder of fixed height with two runged sections joined at the top with hinges and a spreader. A plank can be placed across the top of two trestle ladders to form a work platform. (6) EXTENSION TRESTLE LADDER—Essentially the same as a trestle ladder except for a vertical section that extends up between the angled sections. (7) SECTIONAL LADDER—A ladder made of two or more straight ladder sections that are designed to be locked together to form a single ladder. (8) ARTICULATED LADDER—A ladder with one or more joints that can be locked into position to enable it to be used as a straight ladder, stepladder, scaffold, or work table. (9) PLATFORM LADDER—A self-supporting, non-adjustable ladder with a platform at the highest standing level.

LADDER, WORKING LENGTH
The distance along the side rails of a non-self-supporting ladder from the bottom to the upper support points.

LAITANCE
A thin, weak, brittle layer of cement and aggregate fines on a concrete surface usually caused by an overly wet or overworked mixture, improper or excessive finishing, or a combination of these factors. Laitance can create an egg-shell surface over hidden voids; if not removed before painting, the disintegration of the laitance will leave unfilled holes on the surface.

LANYARD
A rope attached at one end to a D-ring on a safety belt or body harness and at the other end to a lifeline. Most lanyards have double-locking snap hooks and a shock absorber to reduce the impact of a fall being stopped.

LAP
The region where one area of a coated surface merges into an adjacent, freshly coated area during application of a single coat. The objective of the painter is to avoid showing the lap.

LATEX PAINT
A paint containing a stable aqueous dispersion of synthetic resin, produced by emulsion polymerization, as the principal constituent of the binder.

LEAD
A metal, previously used as a pigment in paints. Discontinued in the early 1950s by industry consensus standard, and banned by the Consumer Products Safety Commission in 1978 because of its toxicity.

LEL METER
A device used to measure the concentration of combustible vapors in an air sample and determine whether or not it is explosive.

LEVELING
A coating’s ability to flow out on a surface so that brush or roller marks or other irregularities produced during application are not apparent.

LIFELINE
A safety line that is securely fastened above the job sit to a solid anchor on the building or structure and that extends to the ground. The worker’s safety belt or body harness is attached to the lifeline with a lanyard. An individual lifeline is required for each worker who must have fall protection equipment.

LIFTING
Softening and raising or wrinkling of a previous coat of paint by the application of an additional coat.

LINING PAPER
Blank stock used as a liner or surface conditioner to obtain a smoother surface and better adhesion before other wallcovering is applied. Lining paper can be used to cover rough surfaces such as cinder block, texture surfaces such as stucco or paneling, or cracked or defective surfaces so that the wallcovering will be flat and smooth.

LINSEED OIL
Oil obtained from flaxseed. Linseed oil is used in paints in larger quantities than any other oil. It is considered a fine vehicle for exterior paints because of its excellent drying properties and durability.

LIQUID DRIERS
Solution of soluble driers in organic Solvents.

LIQUID WOOD FILLER
Varnish of low viscosity, usually containing extending pigment, used as a first coat on open-grain woods.

LITHOPONE
A white pigment of barium sulfate and zinc sulfide.

LITMUS TEST
The use of litmus paper or pH paper to measure the acidity or alkalinity (pH) of a water solution.

LIVERING
The progressive, irreversible increase in consistency of a pigment-vehicle combination. Livering usually results from a chemical reaction of the vehicle with the solid dispersed material, but it also may result from polymerization of the vehicle. The irreversible character of the changes distinguishes livered material from thixotropic "build-up," which is reversible.

LONG OIL ALKYD RESIN
An alkyd resin made with a relatively high oil-to-resin ratio.

LONG OIL VARNISH
An oleoresinous varnish, other than alkyd, made with a relatively high oil-to-resin ratio.  Generally slower-drying, tougher, and more elastic than short oil varnishes.

LOW SOLVENT COATING
Generally, a coating that contains a reduced amount of volatile organic compounds (VOCs) in the paint as applied.

LOWER EXPLOSIVE LIMIT (LEL)
The concentration, at ordinary ambient temperatures, of a compound in air below which an explosion will not occur if the mixture is ignited.

LUMINOUS PAINT
A coating that emits light rather than just reflect it. There are three classes: fluorescent, which requires ultraviolet light to activate it; daylight fluorescent, which emits additional light from absorbed solar radiation; and phosphorescent, which continues to glow for some time after the external energy is removed.

M - glossary

MAINTENANCE COATING
A coating, other than the original coating, of which the primary function is protection; used to maintain highway and railroad structures, chemical plants, manufacturing plants, public utilities, and other industrial facilities.

MAINTENANCE PAINTING
All repainting except that done for aesthetics.

MARBLING
Simulating the grain and texture of marble by means of specially prepared colours and stain and graining tools.

MARINE PAINT
Coating specially designed for immersion in water and exposure to marine atmosphere.

MASKING TAPE
An adhesive tape used to protect small surfaces from becoming smeared with paint.

MASTIC
(1) A heavy-bodied coating of high build. (2) An adhesive composition.

MATCHING
Hanging strips of wallcovering so that the design is in correct relation to the preceding strip.

MSDS - MATERIAL SAFETY DATA SHEET
A printed source of information about the hazards of materials including coatings.  The MSDS contains the following information: 1.) product identification; 2.) hazardous ingredients, their permissible exposure limits (PEL), and threshold limit value (TLV); 3.) physical properties; 4.) fire and explosion hazard data, such as flash point, lower and upper explosive limits, and firefighting procedures; 5.) health hazard data; 6.) chemical reactivity/stability data; 7.) spill and leak procedures; 8.) special protection information; and 9.) additional special precautions.

MECHANICAL DRYWALL TOOL
Any mechanical device, such as an automatic taping applicator, used to apply joint compound and/or joint tape or to finish joints in the drywall finishing process.

MEDIUM OIL ALKYD RESIN
Alkyd resin made with a medium oil-to-resin ratio. These resins contain between 40 and 60 percent oil as a modifying agent.

MEDIUM OIL VARNISH
An oleoresinous varnish, other than alkyd, made with a medium oil-to-resin ratio.

MESH GRID
A paint roller accessory that is hung from the top of a 5-gallon pail partially filled with paint. Like the roughened surface of a paint tray ramp, it allows paint to be worked into the roller cover and provides a way of removing excess paint from the roller cover.

METAL SPRAYING
Application of a spray coat of metal (usually zinc or aluminum) onto a prepared surface.

METALLIC PAINT
Paint containing tiny flecks of aluminum or other metal, often used because of its attractive appearance.

METALIZING
The spray application of a coating of metal onto a surface.

MIL
One thousandth of an inch (0.001 inch, 25.4 micrometers). The thickness of a coating on a surface is usually measured in mils.  Metric 'mil' for millimeter equals 1/1000 of a meter.

MILDEW
A fungus growth that "feeds" on paint, wallcovering, and other materials in damp places. It causes discolouration and deterioration.

MILDEWCIDE
An additive used to enhance a coating’s ability to resist fungus growth that can cause discolouration and ultimately decompose the binding medium.

MILDEW RESISTANCE
The ability of a coating or a wallcovering to deter the groth of mildew.

MILL SCALE
The heavy oxide layer formed during hot fabrication or heat treatment of steel and other metals.

MINERAL SPIRITS (PAINT THINER)
A petroleum-derived solvent used for thinning paint. Odorless mineral spirits have been refined to remove some odorous constituents.

MISCIBLE
Capable of mixing or blending uniformly.

MIST COAT
Thin tack coat; thin adhesive coat.

MOISTURE TRAP
A device used to remove moisture from the air lines of abrasive blasting or spray painting equipment. A bleed valve at the bottom of the device is left open slightly to allow water caught in the trap to drain out.

MONOMER
The starting compound for a polymerization reaction. A monomer is capable of polymerizing, or linking together, with itself or with different monomers.

MSDS
See MATERIAL SAFETY DATA SHEET.

MUD
Trade jargon for joint compound.

MUD CRACKING
A paint film defect that has the appearance of dried mud cracks.

MULTICOMPONENT SPRAYING
A paint application method that automatically proportions and mixes two or more components of a paint material in the process of delivering them to the spray gun. Plural component spray equipment is used to apply coatings with a pot life that is too short to permit mixing and application by conventional air and airless spray equipment.

MULTIPACKAGE COATING
Cross-linking paint materials that must be stored in two or more separate containers and that must be mixed in the correct proportion before use. Once they are mixed, a chemical reaction begins and the paint remains usable for a limited time only.

MURAL
A hand-screened, machine-printed, or lithographed mural decoration with a pattern that continues over several strips of wallcovering; intended to cover one wall of a room or the greater part of a wall without a repeat.

MURIATIC ACID
A diluted form of hydrochloric acid used to clean concrete and masonry.

N – glossary

NAIL POPPING
A slight protrusion of nail heads from drywall panels that can be caused by shrinkage of lumber framing, structural movement, or improper application of the fasteners.

NAP
The length of fibers in a paint roller cover, usually described as "short nap," "long nap," etc.

NAPHTHA
Any of several hydrocarbon solvents or their mixtures that are derived from petroleum or coal tar products. Generally, these solvents are composed of aliphatic (VM&P naphtha) or aromatic (high flash naphtha) compounds.

NAPHTHENIC SOLVENT
Hydrocarbon solvent comprised primarily of ring compounds of saturated hydrocarbons (cycloparaffinic, naphthenic). These solvents fall between aliphatic and aromatic solvents. Examples are cyclopropane, cyclobutane, cycloheptane, and cyclohexane.

NATURAL RESIN
Solid organic substance, originating in the exudation of trees or plants, the secretion of insects, or fossilized vegetable matter in the earth. These resins are thermoplastic, flammable, and nonconductive of electricity. When hard, they break with a conchoidal fracture (a fracture whose surface resembles the inside of a clam shell), and they dissolve in certain specific organic solvents but not water.

NEAR-WHITE BLAST CLEANING
High grade of blast cleaning. This standard surface is defined in two slightly different consensus standards.

NEEDLE GAUGE
An air pressure gauge with a needle connected to the air inlet. A needle gauge is used to check the air pressure of a blast system by inserting the needle into the blast hose just behind the nozzle and pointing the tapered tip into the air flow.

NEEDLE GUN
A type of power impact tool that has a bundle of steel needles mounted in front of a piston that strikes them several times per second and impacts them against the surface being cleaned.

NEUTRALIZATION
The process of removing excess acidity or alkalinity from concrete, masonry, or plaster.

NONFLAMMABLE
Incombustible; will not burn.

NON-GRAIN-RAISING STAIN
A solution of dye dissolved in alcohol, ketone, etc. Because it contains no water, it does not raise the grain of woods.

NONMETALLIC ABRASIVE
Natural, byproduct, and manufactured materials used as abrasives for blast cleaning.

NVM - NONVOLATILE MATTER
The volume of dry (cured) coating expressed as a percentage of the volume of liquid coating applied to a surface (e.g., vol. of NVM is 62 percent). This value is useful for comparing the coverage obtainable with different coatings. Often, percentage is given without specifying whether it refers to volume or weight. This is confusing and can lead to errors in coating calculations.

NONWOVEN ABRASIVE PAD
A web of nylon fibers imbedded with abrasive material in different sizes and densities. These pads can be used to remove dried soil, debris, and loose paint from all types of surfaces, as well as loose rust and loose mill scale from steel. They also can be used to feather, or blend the edges of a repair area, with the surrounding surface.

NOZZLE
The fluid orifice of an airless spray gun.

NOZZLE ORIFICE GAUGE
A tapered metal rod that can be inserted into a blast cleaning nozzle to determine the size of its orifice. The nozzle normally is replaced when the orifice size increases by 1/16 inch.

O – glossary

OIL-BASED COATING (PAINT)
A paint or varnish that contains resins or oil varnish and drying oils as the basic film-forming ingredients and is converted to a solid film primarily by chemical reaction (usually oxidation).

OIL LENGTH
The ratio of oil to resin in a medium. For an oleoresinous varnish, the oil length may be expressed in terms of parts by weight of oil to one part by weight of resin.

OIL STAIN
A solution of dye in a blend of oil or varnish and solvents. Some oil stains are pigmented in order to reduce the depth of penetration of the stain.

OIL VARNISH
A varnish that contains resin and drying oil as the basic film-forming ingredients and is converted to a solid film primarily by chemical reaction.

OLEORESIN
A natural plant product that contains oil and resins. Turpentine is an example.

OLEORESINOUS VEHICLE
A vehicle prepared by the addition of a resin to a drying oil.

OPACITY
The property of a paint that enables it to hide and colour a surface.

OPEN ABRASIVE BLAST CLEANING
An air abrasive blast cleaning operation without any localized containment surrounding the blast stream.

OPEN GRAIN WOOD
Wood that has loose, open formation with minute openings between the fibers. Examples: oak or walnut.

OPEN TIME
The length of time a wallcovering adhesive is tacky and bondable.

ORANGE PEEL
The dimpled appearance of a dried coating film resembling the skin of an orange.

ORBITAL SANDER
A power sander with a flat abrasive pad that is vibrated in small, circular motions.

ORGANIC ZINC-RICH COATING
Anti-corrosive primer for iron and steel incorporating zinc dust pigment in an organic vehicle. The most common types of binders for organic zinc-rich coatings are epoxy polyamide, urethane, vinyl, and chlorinated rubber.

ORIFICE
Opening or hole in a spray or blast nozzle.

OUTRIGGER BEAM
A fixed or movable arm that extends beyond the edge of a roof or structure. It is used for rigging scaffolds.

OVERLAP SEAM
See WALLCOVERING SEAM.

OVERSPRAY
Spray particles that are not wet enough to fuse when they reach the surface being sprayed.

OXIDATION
Corrosion of metals and degradation of other substances caused by oxygen in the air.

P – glossary

PAINT BRUSH BRISTLES
Natural or synthetic fibers bundled together and attached to a handle for use in soaking up paint and spreading it onto a surface.  Natural bristles are usually hog bristles or horse hair. Because natural bristles can be softened by the water in water-borne coatings, these brushes are most effective for application of solvent-borne coatings.  Synthetic bristles are usually nylon, polyester, or blends of these. Because some solvents can have a detrimental effect on synthetic bristles, these brushes are most effective for application of water-borne coatings.

PAINT FAILURE
The condition of a paint film at the end of its useful life; the premature deterioration of a coating. All paints must fail eventually, but the method of failure and the suitability of the surface for cleaning and repainting are the important factors that must be considered when undertaking any remedial action.

PAINT HEATER
Device for lowering viscosity of paint by heating it prior to application.

PAINT MITT
A painting tool worn on the hand. This fabric-covered mitt is dipped into paint and then used to apply the paint by grasping or rubbing the surface to be painted.

PAINT PAD
A paint application tool designed to apply paint by a wiping action. It consists of a flat square or rectangular backing covered with very short-napped synthetic fiber and connected to a handle.

PAINT REMOVER
A mixture that softens old paint or varnish and permits it to be removed with a scraper. Paint removers also are called chemical strippers and usually contain solvent, wax, and other chemicals. Paint removers are suitable for removing most oil-based paints, thermoplastic paints, and latex emulsion paints.

PAINT ROLLER COVER
A tubular sleeve consisting of a hollow tube or core covered with natural or synthetic fiber materials. Natural fiber materials are sheepskin, lamb’s wool, and mohair; synthetic fiber materials include acrylic, polyester, and nylon.

PAINT ROLLER COVER NAP LENGTH
The length of the fibers of the material on a roller cover. Different nap lengths are used depending upon whether the surface being painted is rough or smooth. Short-nap covers (1/4 to ½ inch) are used for painting smooth surfaces; long-nap covers (3/4 to 1-1/2 inches) make it possible to work paint into crevices, pits, and other irregularities of rough surfaces.

PAINT ROLLER TYPES
(1) DIP ROLLER Paint is supplied by dipping the roller into a tray or a 5-gallon pail of paint. Excess paint is removed by rolling the dip roller over the roughened ramp of the paint tray or over a mesh grid attached to the 5-gallon pail. (2) FOUNTAIN ROLLER The roller has a hollow core that is filled with paint. Pores in the core allow the paint to saturate the outer fabric covering. (3) PRESSURE-FED ROLLER Paint is continuously pressure-fed through a supply hose to the center of the roller. Like the fountain roller, pores in the core allow the paint to saturate the other fabric covering.

PAINT THINER (MINERAL SPIRITS)
A petroleum-derived solvent used for thinning paint. Odorless mineral spirits have been refined to remove some odorous constituents.

PAINT THICKNESS GAUGE
The wet or dry thickness of a coating on a substrate. Film thickness is measured in thousandths of an inch or mils.

PALM SANDER
A power sander so named because it fits comfortably in the palm of the hand. Palm sanders are handy for finishing woodwork.

PARAPET CLAMP
A device designed to fit over and clamp onto a parapet along the perimeter of a roof or structure. It is used for rigging scaffolding.

PASTE
Wallcovering adhesive or paste is available as powder material, which must be mixed with water at the job site, or premixed material, which is formulated at the factory and ready to use.

PASTE MACHINE
A machine with one or more rollers used to apply either adhesive or prepaste activator to wallcoverings. Paste machines come in a number of sizes and types, including table and floor models.

PATCHING PLASTER
A special plaster made for repairing plaster walls.

PATTERN NUMBER
Indicates the design and colour of a wallcovering. The pattern number should match for all rolls of wallcovering used for a job.

PATTERN MATCH
See WALLCOVERING, PATTERN MATCH.

PEELABLE
A wallcovering that can be dry-peeled and leave a continuous base layer on the surface.

PEELING
Spontaneous disbonding of particles of a paint, varnish, or lacquer film from a surface due to loss of adhesion. Peeling may result if paint is applied to a damp, greasy, or improperly prepared surface. For wood and other porous substrates, peeling sometimes is the result of excessive moisture behind the surface.

PENETRATING FINISH
A finish that sinks into the substrate, as opposed to settling on the surface.

pH
A measure of hydrogen ion concentration indicating whether a solution is acidic (pH less than 7), neutral (pH equals 7), or alkaline (pH greater than 7). The further the pH is from 7 the more acidic or alkaline the solution is. A change of one pH unit represents a ten-fold change in hydrogen ion concentration. For example, pH 4 is 10 times more acidic than pH 5 and 10 times less acidic than pH 3.

PHENOLIC ALKYD RESIN
Alkyd resin system modified with a phenolic resin. Phenolic modifications can perform satisfactorily in water immersion, a service in which unmodified alkyd resins are unsuitable.

PHENOLIC RESIN
Synthetic resin made from phenols and aldehydes. Phenolic varnishes are made by cooking phenolic resins with a drying oil. They are widely used in spar varnishes and many enamels; occasionally used in catalyzed coatings.

PHOSPHATING
Pretreatment of steel and certain other metal surfaces with chemical solutions containing metal phosphates and phosphoric acid as the main ingredients. The result is a thin, inert, adherent, corrosion-inhibiting phosphate layer that serves as a good base for subsequent paint coats.

PHOSPHORIC ACID
A weak acid sometimes used to remove light rust from steel and to pacify the steel surface.

PICKLING
Removal of rust and mill scale from steel by immersion in an acid solution containing an inhibitor. Pickling should be followed by thorough washing and drying before painting.

PIGMENT
Finely ground, natural or synthetic, inorganic or organic, insoluble particles that, when dispersed in a liquid vehicle to make paint, may provide colour and other properties of paint, including opacity, hardness, durability, and corrosion resistance.

PINHOLE
Coating film defect in which small, pore-like flaws penetrate one or more coats of paint to expose an underlying coat or the substrate. This term generally is applied to holes caused by solvent bubbling, moisture, other volatile products, or the presence of extraneous particles in the applied film. Pinholes look like pin pricks in the coating surface.

PINPOINT RUSTING
Tiny, dispersed points of rust that can appear at pinholes and holidays in the coating. Very dense pinpoint rusting can appear on painted steel surfaces where the coating does not completely cover the blast cleaning profile.

PIT
A small hole in the surface of a metal or other material that is deeper than its diameter.

PITTING
Small holes or pits in the surface of a metal usually caused by corrosion.

PLASMA SPRAYING
A spray application process in which metallic or thermoplastic powders are melted in the plasma arc cavity that contains the gas stream of the plasma gun and sprayed onto the surface being coated by means of the flow of the plasma jet.

PLASTER OF PARIS
A white, powdery substance formed by heating gypsum. When mixed with water, it forms a paste that sets quickly.

PLASTIC-COATED WALLCOVERING
Wallcovering with a coating of transparent plastic to withstand washing and resist stains.

PLASTICIZER
A substance added to paint, varnish, or lacquer to soften and add flexibility to the dry or cured coating.

PLURAL COMPONENT SPRAYING
A paint application method that automatically proportions and mixes two or more components of a paint material in the process of delivering them to the spray gun. Plural component spray equipment is used to apply coatings with a pot life that is too short to permit mixing and application by conventional air and airless spray equipment.

POLYESTER RESIN
Synthetic resin made from polyhydric alcohols and polybasic acids, and often dispersed in a suitable monomer. Alkyd resins are a specific type of polyester resins and may be regarded as complex esters.

POLYMER
A material that consists of one or more molecular structural units (monomers) repeated any number of times. Types of polymers are (a) HOMOPOLYMER—a single type of monomer linked with itself any number of times; (b) COPOLYMER—two or more different monomers linked with each other in specific sequences and/or proportions.

POLYMERIZATION
The uniting of two or more small molecules (monomers) to form one large molecule (polymer, macromolecule). The new molecule contains repeating structural units of the original molecules.

POLYURETHANE
A film-forming substance produced when an isocyanate reacts with hydroxyl-containing substances (polyols) to produce an organic compound known as a urethane. It shows good chemical and excellent solvent resistance. Abrasion resistance is also outstanding. Polyurethane coatings can be obtained as air-drying, moisture-cured, or catalyzed types.

POLYVINAL CHLORIDE (VINYL)
A synthetic resin used in the binders of coatings. Tends to discolor under exposure to ultraviolet radiation. Commonly called "vinyl".

POPPING
The development of craters or pinholes in a coating of paint or varnish while it is curing. See CRATERING, PINHOLE.

POROSITY
(1) The ability of a surface to absorb a liquid, vapor, or gas. (2) The presence of numerous visible pits or pinholes in concrete.

POST-CURING
An after-application treatment (liquid curing solution, heat, radiation, etc.) that enhances a coating’s level of cure or one or more of its other properties.

POT LIFE
The useful life of a coating material after the initial opening of its container, or after catalysts, activators, hardeners, or other ingredients are added to initiate the curing reaction. Pot life often depends on temperature and humidity.

POWER FILE
A power tool with a straight or curved file used to remove burrs from metal, or brush spots from wood, plastic, or fiberglass surfaces.

POWER TOOL CLEANING
The use of power impact, scraping, sanding, and brushing tools to remove loose paint, loose rust, and loose mill scale and other contaminants.

POWER WASHING
The use of pressurized water (typically less than 5,000 p.s.i.) to remove surface contamination and debris from steel, concrete, and wood surfaces.

POWER WIRE BRUSH
A power tool with a brush made of knotted or crimped wire bristles in the form of a wheel or a cup.

PRE-TRIMMED WALLCOVERING
Wallcovering from which selvage has been trimmed at the factory.

PRE-PRIMER
Coating developed to penetrate old, loose coatings, such as aged, red lead primers, and seal them to the substrate. Pre-primers have low molecular weight and low viscosity, and they are clear or lightly pigmented. They have high penetrability, but cure to a hard, tough polymer.

PRESERVATIVE
Substance added to a paint to prevent growth of microorganisms both in the can and on the applied paint film.

PREVENTIVE MAINTENANCE PAINTING
Periodic touch-up painting, spot-repair painting and/or application of additional full coats of paint before significant deterioration occurs.

PRIMARY COLOURS
A colour that cannot be produced by mixing any other two colours. The primary colours are red, yellow, and blue. All other colours except black and white are blends of these three colours.

PRIMER
(1) First full coat of paint when two or more coats are applied to a surface. Primers provide adhesion to a new substrate (wood, metal, masonry, or concrete), protect the substrate, and aid in the adhesion of additional coats of paint. The type and condition of the substrate and the total painting system specified for a job affect the selection of the type of primer used. (2) In wallcovering, a primer may be applied to the surface to improve the grip (bonding strength) of the wallcovering adhesive.

PRINTING NUMBER
The printing number or dye lot on rolls of wallcovering indicates whether or not the rolls were printed at the same time. Since there may be slight differences in the colour, alignment, and appearance of wallcoverings printed in different print runs, only rolls from one print run should be used for a job.

PROFILE
The contour or roughness of a surface, especially after blast-cleaning. Profile is important because it gives paint an anchor for gripping to the substrate and forming a good, tight bond.

PROFILE COMPARATOR
An instrument used to determine the profile of a blast-cleaned surface by visual or tactile comparison of the surface with a series of reference surfaces having various profile depths.

PROFILE DEPTH
A measure of the profile of a surface based on the distance between its peaks and valleys.

PROPELLANT
The gas used to expel materials from aerosol containers.

PSI
Pounds per square inch; a measure of compressed air pressure.

PSYCHROMETER
A test instrument used to determine dew point and humidity.

PUMP RATIO
(1) Multiplier of input pressure that indicates output pressure. This is the ratio of air piston area to fluid piston area. (2) For fluid proportioning pumps, the ratio between two fluid piston output volumes per stroke.

PUTTY (glazing compound)
A dough-like material consisting of pigment and vehicle and used for sealing glass in window frames and for filling imperfections in wood or metal surfaces.

PUTTY KNIFE (board knife)
A hand tool with a blade 1 to 2 inches wide. It is used to apply putty or small amounts of other patching materials.