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Paint & Body Dictionary

Accelerator || A chemical substance that when added to a paint or resin will speed up the rate of cure time.

Acetone || A very fast evaporating solvent with high solvency for certain types of compounds and resins. Has a characteristic ether-like odor.

Accelerator || A chemical substance that when added to a paint or resin will speed up the rate of cure time.

Acrylic Enamel || Chemically enhanced enamel formulas, which were the mainstay of the refinish industry. Acrylic enamels use a catalyst to create chemical reactions that produce a paint film with excellent durability, chemical resistance, and gloss. Acrylic enamels are still very popular products, though these paints are being phased out in some areas due to emissions regulations. A characteristic of acrylic enamels is the paint can be polished like a lacquer to a mirror finish.

Acrylic Urethane || A coating based on urethane chemistry, which also includes acrylic chemistry as part of the cross-linked polymer backbone.

Activator || A necessary component used to provide a chemical reaction to cure paint. Another name for hardener.

Additives || Chemical substances added to a finish in relatively small amounts to impart or improve desirable properties. Examples are flatteners, flow agents, fish eye eliminators, etc.

Adhesion || The phenomenon by which one material is attached to another by means of surface attraction.

Air Cap || The front of a spray gun nozzle that directs compressed air against the paint to form and shape an atomized cloud of droplets.

Air Spray || A system of applying paint in the form of tiny droplets. The paint is broken into droplets (atomized) by a spray gun as a result of being forced into a high velocity air stream. The shape and paint density of the resulting droplet cloud can be controlled by air pressure; paint viscosity and gun tip geometry.

Alkyd || A coating based on a polyester binder. Such polyester are chemical combinations of molecules that contain more than one acid or alcohol group. An example is Dulux paint enamel.

Atomization || The formation of tiny droplets of liquid as in the paint spraying process.

Atomization is usually caused by turbulence in an air stream, or a sudden drop in pressure.

Baking || Application of heat to cure and dry a coating. In automotive refinishing, baking is used to speed up the drying of air-drying finishes and is sometimes called force drying. The metal temperature in refinish baking usually does not exceed 180 degrees.

Basecoat || A color coat requiring a clearcoat. The basecoat provides color effects and appearance, while the clearcoat provides gloss as well as UV and chemical resistance.

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

Blending || The mixing together of two or more materials; or the gradual shading of paint from one panel to adjacent areas to assure color consistency.

Blistering || The development of hollow bubbles or water droplets in a paint film. It can occur rapidly or over a long period of time after application. Blistering may occur from the presence of unreacted acid within the paint film.

Blushing || The appearance of whitish or cloudy areas in a paint film, caused by absorption and retention of moisture in a drying paint film. Very common when using lacquer based paints.

Buffing Compound || A soft paste containing fine abrasive in a neutral medium, used to eliminate fine scratches and polish topcoat.

Build || The amount of paint film deposited on a substance .The depth or thickness of which is measured in mils.

Blocking || Sanding primer or topcoats by hand with a flat sanding block. Block sanding the primer is a key technique in getting a wave-free, show-quality result in the final finish.

Bonding Adhesive || Product used to bond body panels into the body structure. Corvettes are built and repaired by bonding the major body panels.

Carcinogen || A material that has either been found to cause cancer in humans or to cause cancer in animals and therefore is considered capable of causing cancer in humans. Findings are based on the feeding of large quantities of a material to test animals or by the application of concentrated solutions to the animal skin. A material is considered to be a carcinogen if (1) it has been evaluated by the International Agency for Research on Cancer (IARC) and found to be a carcinogen or potential carcinogen; (2) it is listed as a carcinogen or potential carcinogen in the Annual Report on Carcinogens, published by the National Toxicology Program (NTP) latest edition; (3) it is regulated by OSHA as a carcinogen; or (4) if one positive study is published.

Catalyst || Sometimes referred to as activators, catalysts contain chemicals that interact with the resins of the base paint, allowing it to cure.

Clearcoat || A paint containing no pigment or only transparent pigment, which provides gloss and durability when used as protection over a basecoat.

Color Coat || The single stage or basecoat that provides the visible color of a coating system.

Color Match || Achieved when the applied color duplicates all aspects of the original color? Appearance in hue, value and chroma.

Color Sanding || The sanding of a paint film to prepare for buffing or recoating.

Compounding || Use of an abrasive material, either by hand or by machine, to smooth and bring out the gloss of the applied topcoat.

Cross-coat || A method of painting application often used with high solids paint. The technique involves a side-to-side application followed by a top-to-bottom application with very little flash time.

Delamination || The loss of adhesion between two layers of paint, causing material to separate from the painted surface or substrate.

Dew Point || The temperature at which water vapor condenses from the air. The dew point varies with the relative humidity.

Dirt Nibs: Small specks of foreign material in a dried paint film. Then can be removed by scuff sanding and polishing.

DOI (Distinctness of Image): A measurement of the accuracy of a reflection in a paint film.

DFT (Dry Film Thickness): The resultant film thickness of a coating after it has reached its final state of dry or cure.

Dry Sanding: A method of abrading the surface by hand or machine without the aid of any lubricant (water).

Dry Spray: Sprayed paint, which loses so much solvent in the air that it becomes too dry to flow out over the surface. This normally occurs when the chosen reducer is too fast for the atmospheric conditions. Dry spray has a lower gloss than the normally sprayed surface and typically more orange peel.

Durability: Refers to the retention of gloss and performance properties in a paint film during the use of exposure to sunlight.

Enamel : A term covering a wide range of paint formulations based on enamel resins. These paint products range from spray-can to bulk paints for industrial or automotive refinish applications, and are normally air-dried, with no catalyst added. Cheap refinish enamel is notable for slow-drying, poor surface quality, and marginal durability. Although some low-line enamel products can be enhanced with available catalysts, these products are the realm of bottom-barrel cheap paint work.

Epoxy: A type of paint, adhesive or plastic noted for high mechanical strength, corrosion resistance good adhesion, stability, and chemical resistance.

Etching Primer : A primer with chemicals that etches into the bare metal for better adhesion. It is sometimes referred to as self-etching primer.

Evaporation: The change from liquid to a gas. When solvents leave a wet paint film, they usually do so by evaporation.

Evaporation Rate: The speed with which any liquid evaporates.

Filler : Any material designed to fill surface flaws. Generally a term for polyester body fillers, but also sometimes used generically to cover spot putty, glaze, and even primer surfacer.

Film Thickness Gauge: A device used to measure the coating thickness (film build) on a substrate. Magnetic units are used to measure the thickness of ferrous metals; electronic units are used on non-ferrous substrates.

Fisheye : Surface defects exhibiting small circular depression devoid of paint, usually caused by surface contamination with oils or silicones. If fisheye becomes apparent when spraying, a fisheye eliminator additive can be added to the paint.

Flake Orientation: The appearance of the metallic particles in a paint film during and after dry or cure. Selection of the correct aluminum flakes in the color mixing formula, proper application, etc., will lead to good flake orientation and thus to good color match and appearance.

Flash Point: The temperature at which the vapor of a liquid will ignite when a spark is struck.

Flash Time: The time between paint application and consecutive coats, and/or force dry. In other words: The time required for the majority of quick-evaporating solvents in the material being sprayed to evaporate or “flash” from the surface.

Fluid Needle: Parts in a spray gun that opens and closes fluid passages.

Flowout : The desirable characteristic of droplets of sprayed material to meld together and level on the surface once the product is applied. Air pressure, gun atomization, the amount of material being applied, and the “speed” and/or quantity of the solvents all affect the flowout.

Force Dry: A method of accelerating the drying of paint by using heat.

Glaze : Materials used to fill minor imperfections to improve the surface quality of body filler. Glazing putty was traditionally a single component acrylic, but today, catalyzed polyester putties are commonly used. Fine grain and easy sanding are the primary characteristics of glazing putty.

Gloss: The ability of a surface to reflect light. Measured by determining the percentage of light reflected from a surface at certain angles.

Gravity-feed Gun: A paint gun with the paint reservoir on the top of the gun, which allows the paint to flow into the spray area by gravity.

Guide Coat: A reference coat. For example: a thin coat of dark or tinted color applied over a primer to provide a visual check for low areas when sanded.

Hardener: A necessary component specifically designed to ensure cure of an enamel finish. Another name for an activator.

Hiding or Hiding Power: The ability of a paint film to mask the color or pattern of a surface. May be measured while the paint is still wet or after it has dried, and these measurements may differ. Hiding power is measured by determining the minimum thickness at which a film will completely obscure a black and white pattern.

High Solids: Paints are described as having high solids when they contain more than 50-60% solids (by weight). High solids paints have lower VOCs.

Holdout: The ability of a surface to keep the topcoat from sinking in and causing a decrease in appearance or gloss. Usually in terms of primer sealers.

Humidity: A measure of the amount of water vapor in the air. Absolute humidity reflects the quantity of moisture in the air compared to the maximum possible moisture content of air at the same temperature. Relative humidity is expressed as a percentage. Humidity has a great effect on the drying time of paints, in particular waterbornes and lacquers.

HVLP : Stands for High-Volume/Low-Pressure. It refers to the design of modern spray equipment originally introduced to meet air-quality regulations by reducing air-borne overspray.

Isocyanate: A hardening agent used with acrylic urethane and other 2-component reaction type paints. It reacts with acrylic polymer, etc., to form a very durable coating.

Lacquers: Paints that dry by evaporative loss of solvent. The film remains susceptible to attack by the same or similar solvents. Lacquers can be based on nitrocellulose or acrylic resins. The old standard for custom paintwork. Lacquers are a distinct paint type characterized by fast drying times and the ability to be easily polished to a beautiful luster. Poor chemical resistance and durability are the downside, often resulting in surface cracking and fading.

Low Film Build: The condition of a paint film when it is too thin to provide protection to the substrate or withstand environmental conditions.

Metallic Paint: Paint, which contains metallic pigment, usually in the form of tiny flakes. Generally these are aluminum or mica, and are used to increase the eye-appeal of the finish.

Mica (Pearl): A pigment used to increase the eye-appeal of the finish.

mil: A measure of paint film thickness, equal to one one-thousandth of an inch (0.00l inch).

Mist Coating: A light spray coat of high solvent content material for blending and/or gloss enhancement and metallic control in single-stage color, sometime known as drop coat or dust coat.

Mix Ratio: The proportion of ingredients to be blended together to make a ready-to-spray paint.

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. . Usually caused by improper air pressure, mixing ratio, solvent speed, gun technique, or a combination of the preceding.

Over-reduce: To add more thinner or reducer to a paint than is normally necessary for application. This is sometimes done in order to lower the paint viscosity, to aid in blending, or to achieve a special color effect.

Overspray : Atomized particles of the refinish materials being sprayed that become airborne and do not flow onto the panel being sprayed. Overspray becomes debris, which can ruin the finish or detailing of areas that are not being painted, and can settle as unwanted dust on adjacent panels to be painted in a poorly evacuated paint booth.

Pigment: Small particles added to paint to influence properties such as color, corrosion resistance, mechanical strength, etc. Pigments may be colored, semitransparent, black, white or colorless. They must be incorporated into a paint system by some dispersion process.

Pinholes : Surface flaws in the form of small pin-sized holes in the paint, often resulting from excessive solvents, inadequate flash time, or surface contamination. Also in body filler.

Polyester Resin : Resin type used for fiberglass work, and the material basis for the Corvette fiberglass body.

Polishing Compound: A material applied to a paint surface, which removes minor imperfections with minimal cutting action. Buffing restores film to a high gloss appearance.

Pressure-feed Gun: A spray gun equipped with a separate paint container that is pressurized and connected to the spray gun by means of hoses.

Primer-sealer: A primer undercoat which improves adhesion and holdout of the topcoat, and which seals old painted surfaces that have been sanded; usually does not require sanding.

Primer-surfacer: A primer designed specifically to build thickness for filling shallow surface and small imperfections in the substrate and which usually must be sanded.

Reducer: A solvent used to reduce or thin enamels, urethanes, polyurethanes and epoxies to sprayable viscosity.

Sagging: Excessive flow on a vertical surface resulting in drips and other imperfections on the painted surface. Occurs not only when the paint is wet, but also during baking in certain types of paints.

Sealer: An undercoat that enhances adhesion. Provides uniform color holdout and an even, level surface for topcoat application.

Seam Sealer : Putty-like product used to seal seams or gaps in the body. Available in solvent-based formulations, as well as water based, in bulk cans, or caulking tubes. Seam sealer is used in hidden areas of the bodywork, such as the door jambs and cowl where appearance is a secondary concern.

Shrinkage : The characteristic of paint or filler to “shrink” with time as a full cure is reached, making surface flaws and sanding scratches reappear. Common with older air-dry, lacquer-based primers and acrylic spot putties.

Single-Stage : A paint system in which the color and gloss properties are both contained in a single topcoat product.

Solids: The part of the paint that does not evaporate but stays on the surface to form a film. Usually measured on a weight or volume basis.

Solvent: A liquid, which will dissolve something, usually resins or other binder components. Commonly it is an organic liquid.

Spot Repair: A type of refinish repair job in which a section of the car smaller than a panel is refinished (often called “ding” or “dent” work). The paint is usually blended into the surrounding area.

Stabilizer: Something added to paint to prevent degradation.

Substrate : The surface any primer or topcoat is applied over.

Suction Feed : A configuration of spray equipment where the paint material is drawing into the gun from a cup at the bottom by the venturi action of the gun.

Tack: The stickiness of a paint film or an adhesive. The time it takes for an air drying paint to reach a tack-free stage is a common measure of drying speed.

Tack Cloth or Rag: A cheesecloth coated with a sticky substance used to remove dirt and lint prior to painting.

Tack Coat: The first l coat, applied full and allowed to flash only until it is quite sticky.

Thinner: Solvent added to lacquer-based reduce its viscosity to sprayable consistency.

Topcoat: The final layer of paint applied to a substrate. Several coats of topcoat may be applied in some cases.

Two-Stage: A paint system in which the color is applied as a primary product (basecoat); followed by the clearcoat to provide the gloss and reflectivity.

Two-component System: Materials such as some paints, fillers and adhesives, which require the addition of a hardener or activator to accomplish a chemical reaction, causing them to cure. Also described as 2K.

Undercoat: A first coat, primer, sealer or surfacer applied to the substrate. Frequently used to provide corrosion protection and adhesion.

Urethane: A type of paint or polymer, which results from the reaction of an isocyanate with a hydroxyl containing component. 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.

Viscosity: The flow rate of a liquid. Solvents affect the fluidity or flowability of the paint. Paint viscosity must allow proper atomization and flowout. Viscosity can be determined by measuring the time it takes for a given amount of liquid to flow through a set orifice.

VOC: Volatile Organic Chemicals. The VOC levels of the final sprayable mix of the various undercoat, paint, and clearcoat products is highly regulated in some regions.

Waterborne: A type of paint, which uses water as its primary carrier rather than typical organic solvents.

Wet-Sanding: Sanding with waterproof sandpaper using water to wash away the sanding debris. Creates a higher quality surface than dry sanding, and allows the sandpaper to last longer without clogging.

Zahn Cup: A device to measure viscosity. It is calibrated in different sizes (numbers) for different liquids.

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