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Auto Body Glossary

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2K – Is when two components are mixed to use a material.  For example, 2K primer is the primer and a catalyst.  

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

Acrylic urethane – Is a coating based on urethane chemistry which also includes acrylic chemistry as par of the cross-linked polymer backbone.

Additives – Are chemicals added to a paint to improve or create certain specific characteristics, i.e. flex agents.

 

Air-drying – The process of drying fully during exposure to air at normal temperatures.

Alligatoring – is when paint cracks into large segments resembling alligator skin.

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

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

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

Back sanding – is a technique of sanding a surface to taper the paint film away from the metal repaired area.  This may also be known as “feathering”.

Basecoat (BC)/Clear – A paint system in which the color effect is given by a highly pigmented basecoat.  Gloss and durability are given by a subsequent clearcoat.

Bench – A heavy metal platform used to restore a vehicle’s structural geometry to factory specifications.  This is done by securing a portion of the vehicle to the platform, then pulling appropriate areas of the vehicle into place using special clamps, chains and hydraulic wrenches. 

Binder – Is an agent that helps keep pigment suspended in solution.

Bleeding – Is when a substrate tends to allow it’s color to matriculate through the top 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 – Is 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 – Is and effect of pressure from air, solvent or moisture under a coating causing a swelling or blister in the finish.

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

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

Breaking back – Is a term used to describe the action that takes place when the layers being described are not feathering smoothly onto 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 – Is an 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.

Catalyst – Is 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 a curing agent is. 

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

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

Clearcoat – The clearcoat imparts gloss and protection to a basecoat clearcoat system.  It is essentially pigment-free paint which enhances the color and depth of the color coat.

Compounding – The action of using an abrasive polishing material either by hand or by machine.

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

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

Cross coat – Is applying paint in a crisscross pattern.  Single coat applied in one direction with a second single coat applied at 90° to the first.

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

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

Die-back – Is the gradual loss of gloss due to continued evaporation of solvent after the paint work is finished. 

Direct Gloss (DG) – A topcoat paint which contains pigment and resin and gives the required gloss level without the need of the application of a clearcoat.  A DG Paint film has good weathering and durability characteristics.

Double header/double coat – The process where two coats are sprayed without waiting for the first to “flash-off” and which is used to build up a thick layer of paint. 

Dry Film Thickness (DFT) – Is the thickness of paint after it has dried and/or cured.  This is measured in mils.

Dry Spray – Is a 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 a poor finish.  This may also be caused by air pressure that is too high.

Drying – The process of change of a coating from the liquid to the solid state by evaporation of solvent, chemical reaction of the binding medium or a combination of these processes.  When drying take place during exposure to air at normal temperature it is called “air drying”; if it can be accelerated by the application of a moderate degree of heat it is called “force drying” or “low bake”

Edge to edge repair – a term denoting a complete panel repair as opposed to a touch-up or spot repair.

 

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

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

Featheredge Splitting – Are fracture 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 – Is the sanding process where a painted surface is worked until there is not step or lip where the paint and metal meet.

FEE (Fish Eye Eliminator) – Is an additive used in paint to prevent the occurrence of fish eyes in a freshly painted surface.

Fish Eyes – Are small craters which will appear in the paint if silicone or wax has not been removed from the panel being sprayed.

Gloss – Is the degree to which a painted surface possesses the property of reflecting light in a mirror-like manner.

Hardeners – Are the chemicals added to paint that make the paint harden as opposed to drying.

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

Mapping/ringing – Is 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 – Is the temporary covering of areas not to be painted.

Matte finish – Is a finish with no gloss.

Metallic – A term used for finishes incorporating fine metallic particles, usually aluminum, in paint.

Mica – A naturally occurring mineral based on silica, which after treatment is used as an effect pigment in coatings.  Their special property is that light falling on a mica particle, depending on the angle of illumination, reflects the light with a change in color.  Because of this they are sometimes referred to as “pearls”.

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

Motor manufacturer’s primer – Is an undercoat system applied by the manufacturer to the metal surface of a commercial vehicle or to new automobile panel parts to give protection during transit, storage etc. and which, depending on its type, age and condition, may be able to support the finishing system.  It may consist of more than just a simple primer coat.

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

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

Opacity – Is the ability of a coat of paint to obscure or cover an underlying surface.

Orange peel – Is a common problem which occurs when the wet paint does not flow properly on the panel after spraying and is similar to the texture on the surface of an orange.

Pigment – Is the coloring matter in paint.  A pigment is different from a dye in that a pigment is insoluble in the media in which it is used.

Prep – Is the process of washing, degreasing ad lightly abrading a panel prior to applying paint. 

Pretreatment (metal) – Is the chemical treatment of unpainted metal surfaces before painting, for enhanced adhesion and corrosion resistance.

Primer – Is the first layer of a coating system applied to an unpainted surface.  Its role is to protect the substrate and to prepare it for the application of a surfacer or topcoat.  It must therefore have above all, excellent adhesion to the substrate and to the coating which will follow.

Primer sealer – Is an undercoat which improves the adhesion of the topcoat and which seals the old painted surfaces that have been sanded.

Primer/surfacer primer/filler – Is a pigmented composition which acts as a primer and at the same time has filling properties such that it may be sanded to provide a smooth surface for the color coat that is to follow. 

Putty – Is a plastic material with a high mineral filler content.  It is used for filling holes or gaps.

Rubbing compound (Polishing Compound) – Is an abrasive paste that smoothes and polishes paint films.

Sealer – Is an undercoat which improves the adhesion of the topcoat and which seals old painted surfaces that have been sanded. 

Solid color – Is a coating which contains colored pigments only i.e. does not contain pigments such a aluminums and micas.

Solvent – A liquid, usually volatile, which is used to reduce viscosity.  This is essential in both manufacturing and application processes.  Solvents evaporate during application and drying of paint and therefore do not become a part of the dried film.  In conventional coatings the solvents are organic compounds (Alcohols, Esters and Ketones) while in waterborne systems there is a mix of organic solvents with water. 

Substrate – Is the uncoated or unpainted surface.

Tack rag – Is a cotton fabric, such as cheesecloth, lightly impregnated with a resin, used to remove dust from a surface after rubbing down and prior to further painting.  Tack rags should be stored in an airtight container to conserve their tackiness.

Tape marking – Is the imprint caused by applying masking tape on a newly-applied paint film before it has had time to harden.

Thinner – Is a blend of volatile organic solvents added to the paint to reduce it to the correct viscosity for application.

Three coat color – Is a topcoat color which consist of 3 parts; a basecoat, a midcoat and a clear.

Tint and blend – Is the process of mixing toners to match the existing paint finish, then blending or overlapping the color into the adjacent panel to avoid color match problems.

Tinter – Is any colored pigment or paint mixture used to make small adjustments in color, or to the mix the color in the first place from a mixing scheme.

Top coat – Is the final layers of a coating system whose role is primarily decorative.  However, the topcoat often imparts protection to the ultra violet light present in sunlight.

Two-pack – Is a paint or lacquer supplied in two parts which must be mixed together in the correct proportion before use.  The mixture will then remain usable for a limited period of time.

UV absorbers – Are chemicals added to paint to absorb Ultraviolet radiation present in sunlight.

Undercoats – Are first coats of primer, sealer or surfacer.


 

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