Autobody Terms



Abrasive – A coarse material, such as wet or dry sandpaper that is used to rub against the surface to be altered in order to: 1.) Make it smooth, 2.) Make it rough, 3.) Remove the surface material.

Acid Core – Solder in a tubular wire

Acrylic – A plastic like material used in the manufacturing of paint to increase gloss and durability.

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

Adhesion – The attachment between two surfaces or coatings i.e. the primer improves the adhesion of the paint to the surface.

Air Brush – A very small spray gun used for spraying smaller areas as in custom painting artwork and pin striping.

Air Dry – When paint is capable of drying at room temperature without the need of heating or the addition of a catalyst.

Air Hose – A rubber, plastic or cloth woven hose used to carry compressed air from it’s storage tank or compressor to be used for the operation of air tools (like sanders or spray guns) and/or breathing apparatus.

Air Line – This term can be used meaning air hose but is mostly used to describe the hard piping that carries the air from the compressor to the regulator/filter where the air is cleaned and the pressure is controlled and where the hose is attached to carry the air to the tools.

Air Pressure -The amount that air is compressed, which is typically measured in “pounds per square inch” (PSI) for use in US auto body industry. However, this pressure can also be measured in other ways including “bars” which equal 14.2 PSI or in “kilonewtons per square centimeter” (Kn.sqcm)

Air Pressure Drop – Is the amount that the air pressure drops between the compressor and the tool being used. This drop is usually a brought about and determined by the initial pressure of the air leaving the compressor, the internal diameter of the pipe or hose carrying the air and the length of the pipe or hose.

Air Storage Tank or Receiver – The air from the compressor is usually pumped into a vessel that holds the air ready for use. The size of this tank is important when the use of the air is beyond the capacity of the compressor to generate. The storage of air can allow the user to use the tool for a longer duration before the need to stop and wait for the compressor to replenish the supply of compressed air. This becomes less of a factor when the compressor is of sufficient size to handle the application.

Air Supplied Respirator – A respirator that provides safe breathing air to a painter while working with paints. The air supply provides not only breathing air but positive pressure on the edges of the mask to eliminate any contaminates from the outside air. (Also known as supplied air or positive pressure).

Airless Spray – A system of applying paint in which the paint, under high pressure, is passed through a nozzle and broken into droplets (atomized) when it enters the lower pressure region outside the gun tip.

Alligatoring – When paint cracks into large segments resembling alligator skin. Similar to “cracking, crazing or checking.”

Aluminum Oxide – Sharp and hard abrasive.

Ambient – Usual or surrounding conditions.

Ambient Temperature – Temperature of the air surrounding an object.

Anionic Electro Deposition – One of the electro coating (E-coat) methods in which the body is charged positively and the paint negatively. Frequently used OEM primer application.

Anodizing – An electrollic surface treatment for aluminum which builds up an aluminum oxide coating to provide better adhesion.

ANSI – American National Standards Institutes. A privately funded, voluntary membership organization that identifies industrial and public need for national consensus standards and coordinates their development. Many ANSI standards relate to safe design/performance of equipment and safe practices or procedures.

Arcing (the spray gun) – the action of turning the wrist or elbow at the end of each pass of paint while doing blends or panel repair. This causes a lighter application of paint at each end of the pattern.

Aromatics – A type of solvent based on benzene ring molecules. Aromatics are often used as diluents. Example are benzene, xylene, and toluene.

Aspiration Hazard – The danger of drawing material into the lungs, leading t inflammatory response.

Atomization – When a paint or other liquid is broken into small droplets allowing for even distribution through a spraying process.


Back Sanding – Technique of sanding a surface to taper the paint film away from the metal repaired area. Also known as feathering.

Basecoat – Highly pigmented paint which requires a coating of clear for protection, durability and gloss.

BC/CC – Base Coat / Clear Coat is the two step process for applying the color first then the shine in the form of the clear coat.

Binder – An agent that helps keep pigment suspended in solution.

Bleeding – When a substrate tends to allow it’s color to matriculate through the to coat. This condition is prevalent in some fillers that will allow their colored hardener to “bleed” through the primers and colors that are applied over the filler.

Blending – A spraying technique that tapers the finish or color so that slight differences cannot be distinguished. Merging one color into another. Tapering the color allows the old finish to show through the new color.

Blistering – Effect of pressure from either air, solvent, or moisture under a coating causing a swelling or blister in the finish; i.e. water blister.

Blushing – A cloudy appearance in the finished paint surface caused by excessive moisture in the air when spraying was carried out.

Body Filler – An activated polyester type material used on bare substrate or over primer to fill in dents in damaged auto body parts.

Breaking Back – Term used to describe the action that takes place when the layers being described are not feathering smoothly into the surrounding material. When a new paint is blended into old then buffed the new/soft material can “break back” if compounded causing a visible flaw.

Bridging – Occurrence where a primer will not fill a sand scratch or imperfection. This may not show in the prime coat but will show in the topcoat. Also a term used to describe paint applied to a surface that extends to an adjacent panel when the film thickness becomes thick enough for the paint to “bridge” the gap.

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


CFM – Cubic Feet Per Minute – The measure of the volume of compressed air passed through an air line.

Carbon Black – A black pigment manufactured by collecting the carbon resulting from incomplete combustion of natural gas.

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.

Catalyst – A substance that changes the rate of a chemical reaction when it is mixed with another substance and that does not change or react itself. A catalyst differs from a curing agent in that the catalyst is not itself chemically consumed in the reaction while curing agent is consumed.

Caulking – Sealing used in joints to prevent the passage of fluid (commonly moisture) or gas.

CC – Short for Clear Coat

Chalking – The result of weathering of a paint film resulting in a white powdery appearance.

Checking/Crowfoot – Tiny cracks or splitting in the surface of a paint film usually seen in a lacquer, caused by improper film formation or excessive film build.

Chemical Cartridge Respirator – A respirator using various chemical substances to purify inhaled air of certain gases and vapors.

Chemical Stain/Spotting – Circular, oblong or irregular spots or discoloration of areas of finish caused by reactive chemicals coming into contact with air pollution (coal and high sulfur emissions), acid rain and snow.

Clear – A finishing coat, such as a coat of paint without pigment (hence “clear”) which protects or covers a color coat and acts as a lens that enhances color and depth.

Color – The effect of light of varying wavelengths on the human eye. In paint, color is created by various tinted pigments.

Color Version – A color matched in a different quality finish, to match the same OEM standard; i.e., a color matched to an acrylic enamel in lacquer.

Compressor – A mechanical device used to compress air. An electric motor ( or a gas or diesel engine) is used to drive a pump which usually consists of a cylinder and a piston assembly. A Two Stage Compressor will have two such assemblies. Air is drawn into the cylinder and compressed by the piston. This compressed air is then either compressed again in the other cylinder or is passed to the storage tank or air receiver.

Coverage – The area which a given amount of paint will cover satisfactorily.

Cratering – The forming of holes in a film due to contamination.

Crazing – Fine cracks on the surface of the paint. Can be caused by old age, or re-coating a synthetic paint before the finish coat has dried properly. Also, an excessive delay in applying a second coat of synthetic where the first coat has started to cure.

Cross Coat – Applying paint in a crisscross pattern. Single coat applied in one direction with a second single coat applied at 90 degrees to the first.

Curdling – The gelling or partial cure of paint due to incompatible materials. This usually occurs during the mixing process.

Curing – A process of drying or hardening of a paint film.

Curtains – Large sagging or runs of paint due to improper application.

Custom Painting – Unique painting, frequently with special effects or designs, normally designed by owner of vehicle or individual painting the vehicle.

Cut-In – Painting of the edges of parts before installation.

Cutting – The use of T-Cut or compound to polish paint to a high gloss. See polishing.


DA – Dual Action – refers to a power tool used for sanding.

Defined Orientation – The dispersion of metallic or mica flake with a definite pattern.

Delaminating – The peeling of a finish having improper adhesion.

Depth – Lighter or darker in comparing two colors. The first adjustment in color matching.

Die-Back – The gradual loss of gloss due to continued evaporation of solvent after the paint work is finished. This problem was a big problem in paint jobs that used paints that had a large percentage of solvent trapped below the surface. Lacquer is know for it’s ability to “die back.”

DOI – Distinctness of image. A measurement of the accuracy of a reflection in a paint film.

Downdraft Booth – A spray booth in which air movement is from the ceiling through the floor.

Double Header (Double Coat) – The process where two coats are sprayed without waiting for the first to “flash-off”. Used to build up a thick layer of paint.

Driers – Substances which, when added in small proportions to oil-based paints results inappreciable reductions in their drying times at ordinary temperatures.

Dry Film Thickness (D.F.T.) – The thickness of a paint after it has dried and/or cured, measured in mils.

Dry Spray – Condition caused by holding the spray gun too far away from the work. The compressed air tends to dry the paint too quickly giving rise to poor finish. Could also be caused by too high an air pressure.

Drying Time – The period between applications of the paint and the drying condition, determined by specified test conditions.

Dust Free – Condition when a paint film has dried enough that it will no longer allow dust to penetrate and stick to the finish. Also know as “Out of Dust”.


Elasticity – The flexibility of the paint film, much needed on plastics and fiberglass.

Enamel – A gloss finish which dries slowly by evaporation of the solvent.

Epoxy – A type of paint, adhesion or plastic noted for high mechanical strength, good adhesion and chemical resistance.

Etch Primer – A primer which etches itself into a surface for good adhesion. Used on Aluminum, fiberglass, meter, etc.

Evaporation – The process where the solvent leaves the sprayed paint during the drying process.

Exempt Solvent – Solvents that do not react with sunlight to form precursors to smog, so their use is thus free of legislative control. Water, Acetone, and a few chlorinated compounds are now considered exempt.

Extender Pigment – An inert, usually colorless and semi-transparent pigment used in paints to fortify and lower the price of pigment systems.

Extenders – Extenders are an added property to allow paint film to take longer to dry, allowing the operator to cover larger areas without the fear of the paint film drying too quickly.


Factory Package Color (F.P.C.) – Car colors that are produced and packaged by paint companies for specific car color codes for use at the refinish level.

Fading – A gradual change in color or gloss in a finish.

Featheredge Splitting – Fractures or cracks along the featheredge which occur during drying or shortly after the topcoat has been applied over primer surface. This problem occurs due to poor preparation, use of too fast solvents in primer, improper flash times and/or too aggressive solvents in topcoat.

Featheredging – The sanding process where a painted surface is worked until there is no step or lip where the paint and metal meet.

FEE – Fish Eye Eliminator

Ferrous – Describes any metal composed of or containing iron.

Film Build – The wet or dry thickness of applied coating measured in mils; also see Dry Film Thickness.

Filter – A device which removes contaminates from another material. for example lumps may be filtered out from paint or water may be filtered out from the compressed air.

Fish Eye Eliminator – Additive used in paint to prevent the occurrence of fish eyes in a freshly painted surface. Sometimes referred to as FEE.

Fish-eyes – Small craters which will appear in the paint if silicone or wax has not been removed from the panel being sprayed.

Finish Coat – The top or gloss coat.

Flash-off – The initial period when most of the solvent in the paint evaporates.

Flash Point – The lowest temperature at which a material, such as solvent, gives off sufficient vapor to ignite.

Flash Time – The time between paint application and consecutive coats, and/or force dry.

Flat – Lacking in gloss.

Flatting – The act of using abrasive paper to rub and smooth a panel or painted surface or the addition of a “flattening agent” to the paint in order to remove the gloss in the finished coat.

Flex Agent – Material added to paint for additional flexibility, usually used for rubber or plastic flexible parts.

Floating – Characteristics of some pigments to separate from solution and migrate to the surface of pain film while still wet.

Flop (Side Tone) – The color of a finish when viewed from a side angle, other than direct.

Flow (or Flow Out) – The ability of a liquid paint film to spread out evenly after application to produce a surface free from application irregularities such as orange peel.

Flow Coat – A coat of color or clear that is applied.

Fluid Cup – The container on a spray gun which holds the paint. Can be mounted above the gun (gravity feed gun) or below (suction feed) or separated from the gun and the paint is fed by a tube to the gun (pressure feed).

Fluid Needle – Part in a spray gun that opens and closes fluid passages.

Fluid Tip – Part of a spray gun that meters and directs the fluid stream.

Fog Coat – A paint coat applied at higher than normal air pressure.


Galvanized – Refers to steel treated with a zinc coating.

Glaze – A very fine polishing material used to gain gloss and shine.

Gloss – The shine or reflection from a painted surface.

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.

Ground Coat – Also known as background coat. A special color undercoat which is used with Pearl coat finishes. A special color coat used on single stage in order to achieve a match.

Guide Coat – A light coat of contrasting color sprayed on prior to sanding a panel. This this layer of paint is removed while sanding and acts as a guide showing low and high places in the surface indicating when the panel is prepared properly.

Gun Body – Part of the spray gun to which all required parts are bolted or attached.


Hardeners (or catalysts) – The chemicals added to paint that make the paint harden as opposed to drying. These chemicals usually contain isocyanates.

High Build Primer – Primer that is usually used over body fillers in order to achieve a smoother surface. High build primer will usually have more of a solid content than a non-high build primer and thereby increase the film build created by each coat sprayed.

High Solid – Paints and undercoats which have more pigment and resin (film formers) than their regular equivalent.

Holding Tank (storage tank) – The tank on a compressor used as a reservoir to store the compressed air. The larger the tank the longer an air consuming tool (like a spray gun) can be use before the compressor must come on to recover the depleted air.

Hold-Out (Color) – The ability of an under-coat to stop or greatly reduce the topcoat from soaking into it.

Hot Spray – The technique of applying paint at an elevated temperature. which reduces the viscosity so that higher solid materials can be sprayed, and allows application with less solvent.

HVLP – High volume. Low pressure. Describes a paint gun that uses a high volume and low pressure of atomizing air to apply material to a surface. This provides higher transfer efficiency and lower overspray.


Induction Period (Time) – An allotted amount of time upon mixing of components for compatibilization. The process is common among the use of epoxy/polyamide coatings.

Initiator – A chemical added to help start a chemical reaction such as polymerization or curing.

Innercoat Adhesion – The ability of one coat of paint to stick to another.

Intermix – The mixing of specific colors by adding different components or colorants to produce a usual mixture at the paint store or shop level.

Iridescents – All colors that contain aluminum, mica, or other particles that impart a metallic appearance to the color. Iridescent colors must be matched carefully at all angles in order to achieve an acceptable appearance.

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.


Jelled – A thickening of paint to an unusable form due to drying or curing.


Lacquer – A paint type made up of pigment, resin and solvent that dries quickly due to the evaporation of the solvent.

Let Down Panel – Panel made by a paint technician with different methods of application and amounts of material, resulting in different shades of the same color.

Leveling – Elongation of paint film occurring from the time the paint particles form a wet film on the surface to the time the film hardens and dries. Paint is said to have good leveling properties when orange peel or texture disappears as a result of elongation. Also known as Flow.

Lifting – The soaking of a solvent into a soluble undercoat causing swelling, then causing the topcoat to wrinkle from underneath, lifting off the surface.

Linnish – A term used to describe a sanding or grinding process when preparing a surface prior to painting.

LVLP – Low volume, low pressure (See HVLP).


Makeup Air – A system that brings and heats air from the outside to a desired air flow and temperature. Also known as Air Makeup System.

Mapping or Ringing – The shriveling of an edge of a repaired area so that an outline of the repair shows through the top coat of paint. In most cases this is caused by the solvents attacking and reacting with the feathered edge of the repair.

Masking – Areas which are not to be painted are covered with a material, usually paper, tape or plastic, that prevents spray from coating the surface.

Matte Finish – A finish with no gloss.

Metal Conditioner – An acid-type cleaner which removes small amounts of rust and corrosion left from mechanical metal cleaning (blasting or sanding), etches the metal for better adhesion, and forms a film which can inhibit further corrosion.

Metallic – Paint containing particles of metal or other solid substance that makes the finish sparkle.

Mica Color – Colors containing various sizes and/or colors of mica. Mica flakes have several optical characteristics allowing light to reflect, pass through and absorb. When added to color alone or with metallic flake, causes the color to look different depending on the angle of view.

Microfiber – Is the terminology used to describe ultra-fine manufactured fibers and the name given to the technology of developing these fibers. Fibers made using microfiber technology, produce fibers which weigh less than 0.1 denier. The fabrics made from these extra-fine fibers provide a superior hand, a gentle drape and incredible softness.

MIG (Metal Inert Gas) Welder – Welder designed to provide a strong weld and not damage thinner metals now on vehicles using different combinations of gas to shield the arc from environmental conditions.

Mil – A measure of paint film thickness, equal to one one-thousandth of an inch (0.001 inch).

Mist Coat – A coat of paint that is applied very lightly in order to achieve a predetermined effect, for instance mist coating metallic can make the particles stand up and achieve a brighter appearance.

Mold Release Agents – Soils which must be removed by a pretreatment prior to refinishing plastic parts to insure adhesion. Internal mold release agents are processing aids needed in the manufacturing of a plastic part. External mold release agents are substrate components at or near the surface which can interfere with paint performance.

Mottling – Blotches in paint caused by uneven metallic or mica particles in the finish.

M.S.D.S. (Material Safety Data Sheets) – Used in locating information on the properties of paint materials.


Nib – A small high spot in a paint job that is usually caused by a dust particle or some other foreign object that adheres to the wet paint and is then painted over causing the “nib”.

Nib File – A small tool used to level high spots in a paint job. These tools are used for runs as well as dust nibs.

NIOSH – National Institute for Occupational Safety and Health. NIOSH evaluates medical, biological, engineering, chemical, trade and other information relevant to hazards and recommends preventative measures to reduce or eliminate adverse health and safety effects from these hazards.

Nitrocellulose Lacquer – Lacquer paint whose resin is formed with cellulose, a natural resin made from cotton.


O.E.M. – Original Equipment Manufacturer.

Opacity – The ability of a coat of paint to obscure (or cover) an underlying surface.

Open Coat – A type of sandpaper coating in which abrasive particles are scattered in a low density to prevent it from clogging up.

Orange Peel – A common problem which occurs when the wet paint does not flow properly on the panel after spraying. Similar to the texture on the surface of an orange.

Orbital Sander – Type of sander that uses circular (orbit) motion to accomplish the sanding of different materials.

Overall Painting – A type of refinish in which the entire car in completely refinished.

OSHA (Occupational Safety and Health Administration) – A federal agency which sets safety and health regulations for most of the U.S. industries and businesses.

Overlap – The amount by which each subsequent pass of the spray covers the previous pass.

Over Spray – Paint which during application, will stick to adjacent panels not being painted or that paint which blows into the air during spraying.

Oxidation – Chemical reaction between oxygen and another substance, causing paint film curing, paint film failure or metal rusting.


PSI – Pounds Per Square Inch, the pre-metric measure of pressure, still in everyday use in industry. The metric equivalent is Kilonewtons per square centimeter. Also measured in Bars (or Barometer) is equal to 14.2 pounds per square inch.

Paint – A mixture of pigment, binder and solvent used to decorate and protect metalwork.

Paint Strainer – A filter used to clean paint as it is poured into the gun cup.

Painter Variables – Painter controlled range or reduction, air pressure, speed of travel, flash time, etc.

Panel Painting – Refinishing of a complete panel, fender or door, etc., as opposed to spotting or blending.

Paper Grade – A measure of the roughness of the abrasive paper. For example, a grade of 80 would be very course, while 600 or 800 grade of paper would be very fine. Grades range from 40 (production paper) or 80 wet or dry, up to 1500 superfine grade.

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

Pearls – Finishes which include mica flakes in addition to the pigment and binder.

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

PEL – Permissible Exposure Limit. Occupational exposure limit established by OSHA. Time weighted average limit or maximum concentration exposure limit.

ph – A measure of the acidity or basicity of a substance in aqueous solution. 7 is neutral. Below 7 is acid and above 7 is basic. The scale is from 0 (strong acid) to 14 (strong basic).

Phosphating – The formation of a layer of zinc, iron or manganese phosphate crystals on the surface of the part to be painted. Phosphate coatings are used to increase corrosion resistance and improve paint adhesion.

Phosphoric Acid – An acid commonly used as a catalyst to speed up the cure of some baking finishes, usually alkyd/nitrogen resin combinations. Also a cleaner for ferrous metals.

Photochemically Reactive – Organic solvents that react with ultra violet light to form oxidants such as ozone and smog.

Pickling – Also known as Wrinkling, Puckering or Shriveling. Fault condition where the surface of the paint wrinkles like the surface of a prune.

Pigment – An insoluble finely ground powder, either natural, synthetic, inorganic or organic that provides color, hardness, durability, hiding and corrosion resistance to paint.

Pin-Hole – Paint imperfection resembling a hole about the size of the head of a straight pin, caused by solvent entrapment or air bubbles.

Plasticizer – A substance added to paint when spraying or coating plastics. This enables the paint to become more flexible and move with the plastic. This additive stops the paint from drying rigid and avoids cracking.

Polishing – The action of rubbing a painted finish to a very high gloss (or shiny) finish.

Poly – A prefix meaning many.

Polyester – A polymer formed from a reaction between many pairs of polycarboxylic acid and alcohol molecules.

Polyester Putty – A fine plastic filler used to fill surface imperfections prior to painting.

Polyethylene – A common thermoplastic polymer.

Polymer – Large molecules built up by the combination of many small molecules through a chemical process called polymerzation. These molecules can consist of many thousands of atoms in chains or networks of repeating units.

Polymerization – The formation of a polymer from monomers by chemical reaction. There are several types of polymerization processes.

Polyolefin – Plastic materials used to make flexible plastic bumpers.

Polypropylene – A common polyolefin thermoplastic.

Polyurethane – A chemical linkage in finishes, plastic parts and flexible parts. Polyurethane paint are known for their durability.

Popping – A paint defect that results in the surface having small bumps or craters that are caused by solvent trying to escape from the lower layers after the surface has “skinned” over.

Pot Life – The time in which a paint is sprayable after mixing. This usually refers to paint that has been mixed with a catalyst or activator. This time can vary from a few minutes to several hours depending on the chemicals and the ambient temperature.

Powder Coating – A coating that is applied to the surface as a finely ground powder then heated above it’s melting point and flows together creating a consistent film.

Pressure – Feed Gun – A spray gun in which the paint cup is pressurized which assists the flow of paint to the fluid tip.

Pressure Pot – A sealed paint cup with a paint gun which puts a measured amount of air pressure into it. This them forces the paint to the gun for atomization.

Primary Color – Red, yellow and blue. These colors resemble no other color and cannot be formed by mixtures of any other colors.

Primer – A type of paint which has little color content but which helps the bonding process between metal and color coats.

Primer/Sealer – An undercoat which improves adhesion of the topcoat and/or seals the surface so that the paint isn’t absorbed. Paint is usually applied to the sealer without the need for sanding as long as it is applied within the time window prescribed by the sealer/paint manufacturer.

Primer/Surfacer – A heavily pigmented primer used to fill in sanding marks and small surface imperfections.

Putty (Spot) – Materials used to fill imperfections in a substance. Composed of a lacquer or polyester resin. Applied with a squeegee/spreader and sanded smooth.

PSI – Pounds per square inch

PVA – Polyvinyl Acetate


Quarter Panel – Usually the metal panel that stretches between the rear door and the rear of the car. Some cars will also name the panel that the front fender bolts to the quarter panel. For instance VW Beetle calls the front and rear panels that the fenders bolt to the “Quarter panels.”


Re-coat – The action of going over a surface already coated.

Reducer – Solvents used to thin enamel paints.

Resin – A clear or semi-clear part of a paint film which gives solids or film build. Resin gives the finish shine, gloss, durability, adhesion, handling and drying characteristics.

Retarder – A slow drying solvent used to slow down evaporation and hence slow the drying of a paint coat.

Rubbing Down – See Abrasive, and Wet and Dry.

Run – Excessive amount of coating failing to adhere uniformly over the surface, thus flowing unevenly in a small area.


Sag – Same as run.

Satin Finish – A semi-gloss finish.

Scotchbrite – A fine wire wool used to prepare a surface for painting. Available in several grades such as fine and superfine.

Sealer – A coating sprayed prior to the top coats that can help with color coverage but normally will be used for helping to hide sand scratches and also help prevent the top coats from shrinking into a more porous substrate like primer.

Sealer or Isolator – A coating needed to cover synthetic paint to allow a re-coat with any other material except synthetic.

Seedy – Rough or gritty appearance of paint due to a very small insoluble particles.

Shrinking – The process where a newly sprayed paint contracts as it dries. See Sinkage.

Silicone – Ingredient in polish which is the greatest enemy of the spray painter. It prevents good adhesion when spraying.

Single Stage – A one-step paint procedure of applying color gloss and durability in one application. No clear is used.

Sinkage – The process where the paint sinks into a porous surface. Gloss is reduced by this process. It also shows imperfections such as stopper edges, scratch marks, etc.

Solids – The part of the paint, pigments and resin which do not evaporate.

Solvent – Any material used to thin paint prior to application, such as thinners.

Solvent Pop – Blisters in the surface of a film caused by trapment of solvent after the painted surface had begun to cure or dry.

Spot Repair – The process or repairing only a portion of a panel or vehicle.

Spray-gun-A device used to apply paint to a prepared surface. Professional spray equipment requires an air compressor to activate the spray-gun.

Spray Pattern – Spray from the paint gun adjusted from a very small, almost round pattern to a wide, flat, somewhat oval shape.

SS – Short for Single Stage paint which is a paint not having a Clear coat.

SSU – Short for Singe Stage Urethane.

Stopper – A body putty used to fill defects such as pinholes after filler has been used.

Striping – This is the most common problem encountered when spraying metallic. Generally caused by one of three things: insufficient overlap between coats leading to a “dry edge”, or using cheap thinners which flash-off at the wrong speed for the paint, or poor gun technique.

Stoving – The action of drying paints by means of heat, rather than by natural air-drying. Stoving is often carried out in a specially heated stoving oven or spray-booth.

Surfacer – A coating applied after the primer. Used to build up the surface and fill minor scratches. See Primer-Surfacer.


Tack Coat – First coat when spraying enamel. It is allowed to dry until sticky.

Tack Free – Time in the drying of a paint film where it is not sticky but not completely cured.

Tack Rag – A special cloth used to remove dust and other contaminants from a panel immediately before it is sprayed. The rag is impregnated with a sticky non-drying varnish.

Thermoplastic Paint – Material which with the addition of heat becomes soft and pliable, returning to solid when cooled, i.e., lacquer.

Thermosetting Paint – Type of paint that becomes hard when heated and thereafter is cured, i.e., enamels, urethanes.

Thinners – The solvent used to dilute many types of paint for spraying.

Thixotropic Agent – The thick material that settles at the bottom of a paint tin. This material must be thoroughly stirred to add body to the paint.

Three-Stage System – A three-step paint procedure. First a highly pigmented color coat is applied to achieve hiding, referred to as the ground coat. This ground coat is then followed by the intermediate coat. The intermediate coat is applied using a transparent mica in a number of single coats until the desired effect is obtained. This finish requires a transparent color or clear coat for gloss protection and durability, which is applied last.

Top Coat – See Finish Coat.

Transfer – Efficiency – The ratio in a percentage of the amount of paint actually applied to a surface compared to the amount of material sprayed.

Two-Pack Paints – A paint or lacquer supplied in two parts which must be mixed together in the correct proportions before used. The mixture will then remain useable for a limited period only.


Urethane – A type of paint or polymer which results from the reaction of an isocyanate with hydroxyl containing component. Urethanes are noted for their toughness and abrasion resistance. Also see Acrylic Urethane, Polyurethane.


Viscosity Cup – A measuring cup used to measure the degree of thickness or thinness of liquid paint.

V.O.C. (Volatile Organic Compound) – Any organic compound that evaporates and subsequently participates in atmospheric photo-chemical reaction.


Waterborne Coating – A coating containing more then five percent water in its volatile fraction.

Wet and Dry Paper – A slightly misleading name given to a waterproof abrasive paper which is almost always used WET. Mostly used for rubbing down paintwork as part of the preparation. More commonly used with a bucket of water to which some soap or washing up liquid has been added. The soap helps prevent the paper from clogging with removed paint particles.

Wet-on-Wet – This is a term describing the process of applying two paint products that doesn’t require sanding in between coats. Epoxy primer can be topcoated using a wet-on-wet process if the top coats are applied within the window of time that allows the materials to bond together without sanding.