A
Acrylic - A coating based on a polymer containing short chain esters of acrylic and methacrylic acid. Acrylics physical properties can be controlled in part by choice of the alcohol used to make the ester. Thus, methyl esters give harder films than butyl esters.

Active solvent - A liquid, which can dissolve a paint binder when, used alone.

Additives - Any one of a number of special chemicals added to a paint to bring about special effects. Examples are plasticizers, light stabilizers and fungicides.

Adhesion - The force that makes two materials stick together. When paint bonds with paint, it is called intercoat adhesion. Epoxies have great adhesion to most surfaces.

Air dry - When a coating dries at normal room temperature, usually between 60 - 80 degrees, with a relative humidity between 40 - 60 percent.

Aliphatic solvent - A type of solvent comprised mainly of straight chain hydrocarbons. Examples are gasoline, kerosene, hexane and naphtha.

Alkyd - A coating based on a polyester binder. Such polyesters are chemical combinations of molecules, which contain more than one acid or alcohol group. They are widely used in waterbase house paints, automotive primers and general industrial enamels.

Alligatoring - Paint failure that resembles an alligator's hide. Usually caused by applying a hard-drying paint over a soft paint or by applying the film too quickly.

Aromatic solvents - Hydrocarbon solvents with a benzene ring nucleus such as xylol or toluol.

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B
Basecoat - A highly pigmented color coat applied prior to a clear coating that gives the system the desired color.

Binder - The paint material that forms the film. So called because it binds the pigment and any additives present into a solid durable film.

Bleeding - A defect in which pigment from a lower coat of paint diffuses into an upper coat and discolors the latter.

Blistering - Pressure under the paint film from vapor or moisture will cause blistering. The vapor may come from trapping solvents or from chemical reaction.

Bloom - A bluish cast forming on the surface of some films. It may be caused by such foreign material as smoke, oil or dust, during the drying process.

Blushing - Usually caused by condensation of moisture during the drying period. The film becomes cloudy or translucent.

Branched polymer - A polymer that has some branching along its backbone chain. Example: low density polyethylene.

Bubbling - Air bubbles in a drying film caused by excessive brushing or vigorous stiffing just before applying. When they break, they may form pinholes in the film.

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C
Catalyst - An additive that causes chemical change, but is not permanently affected by the reaction. For instance, the addition of driers speeds up the oxidation of oils.

Cathodic protection - The prevention of corrosion of a metal by electrically connecting it to a sacrificial anode. The anode is itself decomposed and the object of interest is protected. The sacrificial anode must be replaced periodically.

CELLOSOLVE™ - A solvent originally used for cellulose nitrate lacquer. Chemically it is an ether-alcohol, CH₃CH₂OCH₂CH₂OH.

Chalking - The degradation of a paint film by gradual erosion of the binder.

Checking - Tiny breaks in the surface of the paint film. Usually "V" shaped and underlying surface is not visible.

Chipping - Separation of paint from previous coats in chips or flakes.

Clearcoat - A transparent coating sprayed over a base or color coat to produce high DOI finishes. It also may improve durability.

Cloudy - Hazy appearing film on varnish or enamel.

Coalescence - The fusing or flowing together of liquid particles.

Coating - Any paints, varnish or lacquer. Chemical coatings denote industrial finishes. The act of applying.

Cobwebbing - The tendency of sprayed paint to form strings or strands rather than droplets as it leaves the gun. May be caused by too volatile a solvent or too much air pressure. Particularly true of lacquers.

Cohesion - The state or process by which the particles of a body or substance are bound together.

Conductive primer - A primer which when electrodeposited and cured will not act as an insulator of the coated metallic object, but will conduct current for the electrodeposition of a second coating or topcoat film.

Contrast ratio - The hiding power of paint is usually determined by coating both white and black areas of a drawdown sheet. The brightness of the film over the black area is divided by the brightness over the white area to determine the ratio. Normally expressed as percent. The higher the number the better the hiding.

Copolymer - A polymer comprised of two different monomer units.

Cracking - Splitting of a paint film. Usually occurs as straight lines that penetrate the entire film thickness. Results when overbaked or excessively thick films are low temperature cycled.

Crawling - The tendency of some liquids to draw themselves into beads or drops. Caused by high surface tension or applying paint on a high gloss surface.

Crazing - The formation of surface cracks, often as a fine network, which do not penetrate to the underlying surface. Crazing is sometimes caused by the softening effect of solvents from successive paint coats as in lacquer operations or by over baking.

Critical pigment volume concentration (CPVC) - The volume percent pigment in a paint film at which the particles pack together and contact each other.

Cure - The process by which paint is converted from the liquid to the solid state.

Curing agent - Catalyst to produce drying or hardening effect, or both.

Curtains - Sagging of paint. A curtain effect. Usually caused by applying too heavy a coat of paint.

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D
Defoamer - An agent used to minimize foaming during mixing and application.

Diluent - (1) A liquid which increases the capacity of a solvent for the binder. Diluents cannot dissolve the binder themselves. They are usually used to control viscosity, flash time or cost. Example: Xylol. (2) A white pigment used to reduce the intensity of a colored pigment. Example: Calcium Carbonate.

Dispersants - A surface active agent that aids in breaking down pigment agglomerates when the paint is mixed. It also prevents re-agglomeration in storage.

Dispersion agent - A substance which aids holding pigment in dispersion.

Drier - A catalyst added to speed the cure of oil base paints. Driers are often metal salts of naphthenic acids obtained from petroleum.

Dry film thickness - A measurement usually in mils of the paint film after drying.

Drying time - The expected time for a paint film to harden. Varying by product, temperature and atmospheric conditions, drying time is usually expressed as dust free and completely dry or dry for recoat.

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E
Electrocoating anodic - A process in which negatively charged paint film is deposited on to surfaces of substrates. The deposition occurs as a result of an electric current passing between the object coated and oppositely charged electrode (usually the electrocoat tank walls), while immersed in a bath of water thinned paint.

Electrocoating cathodic - An identical process to that of anodic electrocoating, except the paint film is positively charged and electrically deposited onto surfaces of negatively charged metallic substrates.

Electrodip coating - (Also referred to as electrodeposition, electrocoating and electropainting). A process in which a paint film is deposited on all surfaces of a metallic product by the passage of an electric current between the object being coated and another electrode while immersed in a bath of water-thinned paint.

Electrostatic Spray - Applying paint through electricity. The spray is charged as it leaves the gun. The surface to be coated has the opposite charge. The spray particles are thus attracted to the object with a minimum of over-spray and more uniformity. Advantages are better paint utilization and the ability to "wrap-around" and paint the backside of many objects.

Enamel - A very confusing term as it has several meanings: (1) A paint which forms a film by chemical union of its component molecules during cure. (2) A paint having a high gloss finished appearance. (3) In shop terminology, any paint which is not a lacquer.

Epoxy - A type of paint, adhesive or plastic, noted for high mechanical strength, good adhesion and resistance to solvents, acids, alkali and corrosion. They do not weather well.

Epoxy resins - Condensation of epichlorohydrin and bisphenol. A film made from epoxy resins is extremely durable and solvent resistant. Pure epoxies require strong solvents and a catalyst.

Epoxy ester - These epoxies are modified with fatty acids of drying oils and require no catalyst. They require solvents of less strength than catalyzed epoxy and have good adhesion and color retention. They are less resistant to chalking on exteriors than alkyds. Not as chemical resistant as catalyzed epoxy.

Esters - A type of organic compound in which the molecules contain a RCOOR group. Esters are active solvents for acrylic lacquers. Examples are: butyl acetate and diethyleneglycol diacetate.

Extenders - Low-cost inorganic fillers used to supplement expensive pigments. They may also have an important effect on properties of the coating.

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F
Fading - The gradual loss of color of a paint film due to a chemical or physical change. Usually due to pigment degradation by the ultraviolet radiation in sunlight.

Faraday cage effect - The phenomenon by which charged particles are prevented from entering recessed areas. It is due to the curvature of electric force lines to the nearest grounded surface.

Filming Aids - A resin solvent that acts as a temporary plasticizer to promote good film formation at all probable application temperatures.

Filler - A paint or paste applied to fill holes or other irregularities in a surface prior to painting.

Fisher cup - A viscosimeter that works like a liquid hourglass. The viscosity of a liquid is determined by the time it takes to flow through the opening in the cup.

Fisheye - A surface depression or crater in the wet paint film. Fisheyes are caused by the repulsion of the wet paint by a surface contaminate such as oil or silicone materials. The depression may or may not reveal the surface under the paint.

Flaking - The paint film separates from the substrate and flakes off. A paint failure.

Flash point - The temperature at which the vapor of a thinner or solvent will ignite in the presence of sparks or open flame.

Flash time - The time between paint application and baking. Usually a considerably quantity of solvent is lost during this interval. This solvent loss prevents popping problems in the oven.

Flatting agent - The ingredient used in lacquers and varnishes to give a flat or hand-rubbed effect. Calcium, aluminum or zinc stearate is used. Silicate flatting pigments give a better product than those metallic soaps.

Floating - The tendency of some pigments to separate and float to the surface. Also called flooding and results in a streaked or spotty application.

Flocculation - To form masses of particles either by settling out or forming a get.

Flow - The degree of leveling without brush marks. Excess flow may cause sagging.

Fuzziness - Lower gloss (and DOI) resulting from excessive basecoat film or too dry an application of basecoat.

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G
Glass transition temperature - The temperature at which polymer molecules are able to move fairly freely in the solid state. Rubber is elastic because the molecules at room temperature are above their glass transition temperature and can be easily stretched out of position.

Gloss - The degree of which a surface reflects light. Glossy surfaces are generally very smooth.

Gloss meter - An instrument that measures the degree of gloss of a film by its reflectance. Also called a glossimeter. Most commonly used in a 600 meter that measures gloss at an angle of 60°.

Glycols - An additive that improves freeze-thaw stability and modifies the rate of drying. They can be especially important in wet edge retention properties.

Gravelometer - A device for subjecting a painted panel to impact from air blown gravel to determine its probable service life and method of failure. The extent of failure is determined by counting the number of chips in each of several size ranges.

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H
Hardness - The ability of a dry film to withstand indentation. Often measured with a Tukon Tester or, in a production situation, with a pencil point.

Hiding power - The ability of a paint to mask the color or pattern of a surface. Usually expressed as square feet per gallon or square meters per liter.

High solids paint - Paint containing 35 to 80 percent solids. These products have become popular because of the reduction in solvent emissions associated with their use. They are characterized by high viscosities.

Hydrolysis - Reaction with water. Usually refers to a decomposition process leading to paint failure.

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I
Infrared radiation - Light energy having a wavelength of 2.5 - 50 microns. Such energy is often absorbed by organic molecules thus providing a means of identifying paint binders and additives. Also used for curing paint.

Inhibitor - A chemical added to retard some particular reaction. Examples are anti-oxidants and anti-skinning agents.

Intercoat adhesion - Refers to adhesion between two coats of paint.

Intumescent Coating or Paint - Intumesce means to expand or swell. Intumescent coatings, when exposed to heat, quickly puff up to form a tough spongy matrix that will insulate the surface and deflect heat away. Upon heating, these coatings produce a non-flammable gas which is subsequently trapped by the char which is formed. The expansion of the film can be as much as 50 times the original thickness.

Intumescent coatings can be water-based or solvent based. Water-based coatings offer low-odor, fast-dry, and convenient handling. Emulsions used in these types of paints must be compatible with the multivalent salts and other ingredients typically found in intumescent paints. UCAR Latex 367 is capable of making stable, one-package intumescent paints.

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K
Ketone - As used in paint, these are colorless volatile thinners or solvents.

Kick-out - The precipitation of dissolved binder from solution as a result of solvent incompatibility.

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L
Lacquer - A finish or protective coating consisting of a resin and/or a cellulose ester dissolved in a volatile solvent. Sometimes pigment is added. Dries when solvents evaporate.

Latent solvent - A liquid which cannot itself dissolve a binder but which increases the tolerance of the paint for a diluent.

Latex - polymer dispersions in water that are used in paint to provide the film former.

Latex paint - A paint containing colloidal binder particles formed by emulsion polymerization. Generally applied as a waterbase coating that dries by evaporation and coalescence.

Leveling - The quality of spreading out into a smooth, level film. A paint with good leveling properties will dry without brush marks or the appearance of orange peel.

Lifting - When the solvents of the topcoat penetrate the coat underneath and cause wrinkling. Usually penetrates the undercoat and breaks the adhesion.

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M
Matte - A surface with minimal reflection. The opposite of gloss.

Mottle - A term often used interchangeably with flooding or floating.

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N
Nitrocellulose - A polymer based on cellulose (cotton) widely used in finishing automobiles from the 1920's to the 1950's. Nitrocellulose lacquers reduced the drying time for automobile bodies from days to hours. The first mass production color was "True Blue" (Pontiac 1926).

Non-volatile (solids) - Doesn't evaporate.

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O
Oil Base paints - Paints which form solid films by the air-induced crosslinking of certain unsaturated plant oils known as drying oils. Oxygen is consumed in the process.

Orange peel - An irregularity in the surface of a paint film resulting from the inability of the wet film to "level out" after being applied. Orange peel appears as a characteristically uneven or dimpled surface to the eye, but usually feels smooth to the touch.

Overbake - The result of curing paint films at too high a combination of time and temperature. The film often becomes too hard and may embrittle. Sometimes gloss is adversely affected.

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P
Paint - A material which, when applied as a liquid to a surface, forms a solid film for the purpose of decoration and/or protection. Generally, a paint contains binder, solvent(s), and pigment(s). Often other materials are present to give special properties to the paint film. Examples of such additives are rust inhibitors, light stabilizers and softening agents (plasticizers).

Passivation - The conversion of a metal surface to a less reactive state. A process used to reduce the corrosion rate of metal surfaces.

Peeling - The failure of paint film to adhere to its substrate. Peeling results when contaminated surfaces are painted or when there is an excessive difference between paint and surface polarity or thermal expansion characteristics.

Percent solids - The percent mass of a paint due to its non-liquid components.

pH value - The chemical symbol that together with a number describes the alkalinity or acidity of a solution. 7 is neutral. Below 7 indicates acid condition.

Pigment - Small particles added to paint to influence properties such as color, corrosion resistance, mechanical strength, etc.

Pigment volume concentration - The amount of pigment, by volume, in the non-volatile portion of the paint.

Plasticizer - A low molecular weight substance added to polymeric materials such as paints, plastics, or adhesives to improve their flexibility.

Polyester - A type of paint or plastic containing the chemical group (RCOOCR)_X

Polymers - (Poly meaning many; mer meaning units). Very large molecules built up by the combination of many small molecules. They often consist of thousands of atoms.

Popping - A paint defect characterized by raised bumps in the surface. Caused by solvent vapor forming within the paint after it has begun to "skin-over". The resulting vapor pressure raises the paint surface.

Powder paint - Any paint that is applied to the surface as a dry, finely ground powder and then heated above its melting point so that the powder particles may flow together.

Preservatives - A chemical added to protect the paint against microbiological attack during storage. Usually, the same additive functions as a mildewcide to prevent mildew formation of the applied film.

Primers - Undercoats which bind topcoat to substrate.

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R
Resin - Non-volatile solid or semi-solid exudation from the pine trees and plants. Also synthetically made by polymerizing molecules. Examples of natural resins are rosin and damar. Types of synthetics are alkyds, phenolics, etc.

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S
Sealer - A primer which does not allow succeeding coats to penetrate. Also seals in material that might otherwise bleed through the surface.

Seeding - A lumping of pigment or the vehicle becomes gelatinous, forming relatively large particles in the coating.

Settling - When the pigment separates from the vehicle and settles to the bottom of container.

Silicone oils - Oil liquids containing polymers of alternating silicone and oxygen atoms. They have a surface-tension lowering effect when mixed with paints. Often used to control foaming. Silicone oils can cause fisheyes if they remain on surfaces prior to painting.

Silking - The occurrence of flow lines in a paint film as a result of pigment concentration as the paint flows away from corners or holes in the part.

Skinning - The formation of a thin tough film on the surface of a liquid paint film. Usually due to reaction with the air or to rapid solvent loss.

Solids - The pigment and non-volatile vehicle components of paint. Material which remains on surface. Can be measured by weight and volume.

Solvency - The ability of a pure or mixed liquid to dissolve resin.

Solvent - The liquid or blend of liquids used to dissolve or disperse a paint. A true solvent is a single liquid that can dissolve the paint.

Substrate - A layer lying under another. A material on the surface of which a coating is applied.

Surface tension - A property of liquid or solid matter due to unbalanced molecular forces near the surface. A measurement of this property.

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T
Thermoplastic - A type of polymer that softens and melts when heated and then resolidifies upon cooling. Thermoplastics generally have linear or branched structures. Example: polyethylene.

Thermosetting - A type of polymer which does not soften appreciably when heated. Thermosets may char when heated in air. Generally they are crosslinked polymers. Examples: phenolic or epoxy resins.

Thickener - A material added primarily to control viscosity. Usually, one material serves as both protective colloid and thickener.

Thinner - A liquid used to reduce the viscosity of a paint mixture.

Thixotropy - The tendency for the viscosity of a liquid to be shear rate dependent. When the liquid is rapidly shaken, brushed, or otherwise mechanically disturbed, the viscosity decreases rapidly. Thixotropic behavior is the result of molecules or particles in the liquid forming weakly associated structures which break apart upon agitation.

Tint - To add color. A let down with white. A pastel shade of a color.

Topcoat - Usually the final paint film applied to a surface.

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U
Undercoat - Any paint applied under a topcoat. Often but not always synonymous with the term primer.

Urethanes - A type of paint or polymer characterized by the presence of ROCONHR linkages. Urethanes are noted for their toughness and abrasion resistance.

UV stabilizers - Chemicals added to paint to absorb the ultraviolet radiation present in sunlight. Ultraviolet radiation decomposes the polymer molecules in a paint film and thus UV stabilizers are used to prolong paint life.

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V
Varnish - An unpigmented binder-solvent solution applied to protect or decorate a surface.

Vehicle - The combination of binder and solvents or diluents, which are used to put the binder in a usable, liquid form.

Viscosity - The property of liquid which enables it to resist flow.

VOC - Volatile organic compound.

Volatility - The tendency of a liquid to evaporate. Liquids with high boiling points have low volatility and vice versa. Volatility affects flash-off time and fire hazard considerations.

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W
Water spotting - The occurrence of whitish blemishes on a paint film in areas where water droplets have soaked into the film.

Weatherometer - An electrical testing instrument that accelerates various weather conditions on panels exposed to ultraviolet light and water spray.

Wet film thickness - The technique of applying a fresh coat of paint over an earlier coat that has been allowed to "flash-off" but not cured. This technique minimizes difficulties with lifting or overcuring of the first coat during cure of the second coat.

Wetting agent - An aid to dispersion by addition of substances to lower the surface tension of water.