Lexicon of Painting Industry Terms

Single-component paints and lacquers (also called 1-pack), not needing a hardener to cure.  1K paints typically dry in average ambient temperatures and typically include most aerosol spray paints and lacquers.

Two-component paints and lacquers (also called 2-pack), need a hardener to cure.  Hardeners are usually isocyanates that combine with the base paint or lacquer to form very durable coatings.

A substance that when added to paint will speed up the rate of cure.

A very quickly evaporating solvent with an ether-like odour.  Acetone is a key ingredient in some car paint thinners.

A polymer used to increase the gloss and durability of car paint.  Most water-based car paints contain acrylic.

Another word for hardener.

Chemicals added to a paint formula to improve certain characteristics.  Additives can be used for many purposes including improving paint flow, preventing foaming and altering gloss levels.

A type of primer used on difficult surfaces to improve the adhesion of subsequent coats.  The material used over an O.E.M. or cured insoluble finish to increase the adhesion of the topcoat.

The drying process used for single-component paints and lacquers by exposure to air at room temperature.  Air drying differs from forced drying, which uses an external heat source to accelerate drying.

A paint spraying system that atomises paint at high pressure.  Airless spray is a low-volume high-pressure (LVHP) system in contrast with pneumatic (HVLP) systems that combine low-pressure paint with high-volume compressed air.

Minute particles of light-reflecting aluminium added to paint to create metallic effects.  The size and gloss of the particles can be varied to give different effects.

The general conditions (particularly light, temperature and humidity) found in an environment.  Ambient conditions need to fall within given parameters and be kept stable for most filers, primers and top coats to function, dry and cure correctly.

Describes any substance that is water-based.

Turning the wrist or elbow at the end of each pass to apply the paint or lacquer more lightly at the ends.  Arcing helps to blend the new paint more effectively with the old, creating a gradual transition that can be easily buffed to a fine finish.

The process of turning a liquid into tiny droplets, as used in paint spraying.  Turbulence introduced into an airstream or a sudden loss of air pressure will cause atomisation.

Application of higher temperatures to accelerate drying and curing of a coating.  Baking is often used to dry 1K paints and lacquers, where no chemical process is required to complete the curing process.

Any surface not having a coating such as filler, primer, paint or lacquer.  Bare substrate will often be exposed when repairing a surface and will require suitable priming to protect the bare substrate, ensure good adhesion and deliver a consistent finish.

Also known as colour coat, the basecoat is applied on top of a primer and before the topcoat.  The basecoat provides a strong, even coverage of colour but needs an additional finishing clearcoat to provide high gloss, durability and protection against fading caused by sunlight.

A two-stage finish consisting of a colour coat and a clearcoat.

The component in a paint that binds together its pigments and additives.

Bleeding occurs when soluble dyes and pigments in old paint are dissolved by solvents in a new layer and stain the new colour.

Blending is either the mixing together of two substances or colours to make a third substance or colour, or to taper the overlaying of one coating with another in such a way that the differences cannot be detected.

Water droplets or hollow bubbles of air forming in a paint film.  Blistering can happen immediately following paint spraying or after a period of time.

Milky or cloudy patches caused by moisture being absorbed and retained by a paint film during the drying process.  Blushing occurs in the presence of high humidity, where moisture condenses on the wet paint film. It can be prevented by increasing the temperature and reducing the humidity of the paint spraying area and by using a slower-evaporating thinner or retarder.

A two-component activated polyester putty used to repair damaged surfaces of vehicle body parts.  Body filler is easily applied to damaged areas by hand and can be shaped and sanded to restore the appearance of the damaged area. Colour coats and topcoats adhere well to fully cured body filler providing it is free of moisture.

A two-component activated polyester putty used to repair damaged surfaces of vehicle body parts.  Body filler is easily applied to damaged areas by hand and can be shaped and sanded to restore the appearance of the damaged area. Colour coats and topcoats adhere well to fully cured body filler providing it is free of moisture.

A mildly abrasive soft paste used to eliminate fine scratches in a topcoat.  Buffing compound can be applied by hand or with a buffing machine, but whatever method is used it is important that the buffing pad is kept moist with buffing compound to prevent it from overheating and melting the topcoat.

The thickness of a film of primer, paint or lacquer applied to a surface.

Bubbling of the paint during oven drying.  This is caused by air trapped in weld joints or poorly applied filler expanding in the heat.

Burn through happens if a topcoat is polished or buffed too hard or for too long, revealing the colour coat or primer.

A synthetic polymer-based alternative to car wax.

A variation of a colour influenced by another colour.  For example, a blue may have a slightly red or green cast making it a distinguishably different colour while still defined as blue.

Hardeners used in body fillers and 2K paints and lacquers are also known as catalysts or activators.  A catalyst is a substance that when added to another substance will cause it to change its nature without the catalyst being itself affected.

A natural polymer or resin derived from cottonseed oil, used as an ingredient in some paint coatings.

Deterioration of a painted surface, giving a white, powdery appearance.  Chalking is caused when UV radiation from sunlight degrades the paint film’s binder or resin. The exposed particles of pigment then become loose, resulting in the powdery appearance.

Checking is when tiny cracks or splits appear on the surface of a lacquer.  This is caused by a too-heavy build in the lacquer or the film not being formed properly.

Chemical stain occurs when reactive chemicals in the paint are exposed to air pollution.  Acidic pollutants caused by acid rain, coal and high sulphur emissions are some of the pollutants that cause chemical spotting, which takes the form of discolouration or circular, oblong or irregular spots.

A topcoat that contains no (or only transparent) pigment, used to improve the gloss and lustre of the paint layer.  Clearcoats also provide added protection against scratches and chips, and contain additives that filter out the harmful UV rays in sunlight that cause deterioration and fading.

A hazy appearance seen in a liquid or film.  Clouding can happen if much pressure is applied during the final application of a clear coat.

Also known as the paint layer, the colour coat provides a strong, even coverage of colour.  It also carries the aluminium or mica particles that create metallic paint effects.  Colour coat requires a finishing top coat to add gloss and lustre and to protect it against damage from dust, scratches and UV radiation.

Paints with a greater colour-fastness are more resistant to fading when exposed to UV radiation.  Some pigments (particularly red and white) fade or discolour more quickly under UV radiation. Additives in paints and clear coats help prevent this.

A good colour match is achieved when no perceptible difference can be seen between two colours under identical conditions.  Colours react differently in different lighting conditions, when applied to different surfaces and when viewed from different angles.

Colour retention is the ability of a paint to retain its original colour over a period and under different environmental conditions.

Small samples of OEM colours from vehicle manufacturers that establish the required colour to match the factory-original paint colour and set a standard that should be adhered to when colour matching.  A small sprayed-out sample of OEM colour. This is the established requirement for a given colour code.  This is the colour the car is supposed to be from the factory.

A colour formulated to match the OEM standard when a different paint type is used.  For example, the OEM paint might be an acrylic enamel and the Colour Version will be the correct formula to colour match it when using a lacquer.

A mixture of ground pigments, solvent and resin to produce colours.

Colours that sit opposite each other on the colour wheel.  The colour wheel can be used to determine what colours can be used as a contrast yet remain complementary to each other.

Use of an abrasive material to improve the smoothness and gloss of a topcoat.  Compounding can be carried out manually or with a polisher.

The ratio of pigments to resins used in a paint formulation.

The effectiveness of a pigmented paint to evenly cover and conceal an underlying surface.  Pigments vary in coverage from colour to colour, with red having the lowest and white having the highest. White can contain a higher percentage of opaque pigments without altering its colour, whereas red quickly becomes pink in appearance when these are added.

Holes forming in a film of paint due to contamination.  Common sources of contamination include oils, greases, waxes and silicone residues.  These might be environmental or due to contaminated paints.

Fine line cracks visible in the surface of the paint.  Crazing is caused by applying the colour or clearcoat too heavily, trapping solvents under the surface as it dries.

A method of paint spraying that applies the second layer at 90 degrees to the first layer, with very little flash time between coats.  Crosscoating is often used with paints that have a high build.

Tiny cracks visible in the surface of the lacquer.  Crow’s feet are most commonly caused by applying too thick a layer of lacquer, not allowing sufficient flash time between coats and force drying a primer or colour coat. They can also happen if you add too much hardener to the primer or colour coat.

Curdling is when paint or lacquer only partially cures.  Curdling is generally caused by using incompatible materials, preventing a proper cure.

Two-component fillers, primers, paints and lacquers undergo a curing process, after which they reach maximum hardness and chemical resistance.  Curing is different to the drying process of single-component paints. While it is affected by environmental conditions such as temperature and humidity it is also a chemical process. Curing typically takes more time than drying and a two-component finish may feel dry before it is fully cured.

Large areas of sagging or paint runs.  Curtaining is caused by improper paint application.

An abrasive medium suspended in a paste used to remove oxidised paint or scratches.  Cutting compound is available in a range of grit sizes appropriate to the level of paint ‘cutting’ required.

The pattern of aluminium pigments or mica flakes in a metallic paint finish.

Loss of adhesion between two bonded layers.

The comparative lightness or darkness of a colour.  When matching colours, depth is the first adjustment made to bring the mixed colour closer to the original.

The temperature point where water vapour condenses in the air.  At the dew point, water vapour becomes heavier than air and falls onto surfaces, creating dew. The dew point varies depending on the relative humidity of the air.

Gradual decline in the gloss level of paint.  Die-back occurs as the solvents in the paint or lacquer continue to evaporate after polishing.

The colour that paint appears when it is viewed directly rather than at an angle.

Dirt nibs occur when specks of foreign matter enter the paint film while it is wet.  If they are small enough, dirt nibs can often be removed by careful scuff sanding and polishing.

Lacquer particles that remain suspended due to a solvent being too weak to completely dissolve them.

A measurement of how clearly an image is reflected in a paint film.

An additive used to enable or accelerate the paint drying process.

Paint dries as the solvents evaporate.  Not the same as curing.  Drying time varies depending on the type of paint, the solvents and other additives added to it, and the ambient temperature and humidity. Different ‘dry’ levels include ‘tacked off’, ‘touch dry’ and ‘fully dry’.

The final thickness of a coating after full drying and curing.

A fine black powder applied to a surface during sanding to highlight imperfections and sanding marks.

Abrading a surface without a lubricant such as water.

When paint loses so much solvent while airborne that it cannot flow across the surface.  Dry spray occurs when the solvent used evaporates too quickly for the ambient temperature and humidity. The result is a less glossy, and sometimes slightly grainy texture.  Dry spray can be corrected by using a slower-evaporating solvent.

How well a coating performs over time when exposed to wear, weather and sunlight.  A paint or lacquer with good durability will not easily chip, flake, discolour or fade.

The result of topcoat solvents penetrating the undercoat, giving a wrinkled appearance around the repaired area.  Edge mapping may be caused by excessive sanding of the topcoat, exposing the bare substrate.  It can also be caused by incorrect or incompatible filling or priming, or by the filler or primer not being fully cured before the topcoat is applied.

Use of an electrical current to direct paint particles from the spraying equipment to the surface.  In electrostatic paint application, the spraying equipment is positively or negatively charged and the surface is charged to the opposite polarity so that the paint is attracted magnetically to the surface.  This reduces mess and waste due to overspray and creates a more evenly dispersed paint layer across the entire surface.

In paint shop terminology, enamel is any paint that isn’t a lacquer.  Enamel paints remain hard for a long time, whereas lacquers will gradually soften.

Any filler, primer, paint or clearcoat that is cured by the addition of epoxides, generally in the form of a hardener or activator.  Epoxy fillers and coatings are popular because they offer good adhesion, cure quickly to a very hard finish and are highly resistant to chemicals.

Chemical treatment of a substrate to remove rust and to improve corrosion resistance and primer adhesion.

The speed at which solvents are removed from a wet paint film by evaporation.

Paints that are supplied pre-matched to manufacturer’s car colour codes.  While an FPC may cost more than mixing colours from a standard palette in the paint shop, the time they save and the accuracy of the colour matching are strong factors in their favour.

A gradual reduction of colour intensity or gloss.  The primary cause of fading in car paints is UV radiation from sunlight. Colours at the warm end of the spectrum (especially red) are particularly prone to fading.

Sanding a broken paint edge to taper it to a smooth finish.

Merging a new paint layer with the original underneath by applying an indistinct spray pattern along its perimeter.

A primer coat with a high-build formulation that fills minor surface imperfections while preparing the surface for a colour coat.  Where imperfections are minor, filler primer can be used in place of fine surface filler and like a filler, it can be easily sanded to create a smooth, paint-ready surface.

A device that measures the thickness (build) of a coating.

A crater-like depression in a wet paint film.  Fish eyes appear when wet paint is repulsed by a surface contaminant such as oil or silicone.  Depending on the type and level of contamination, the underlying layer may or may not be visible through the fish eye.

The pattern of aluminium or mica flakes in a metallic paint finish.  Matching the flake orientation of an original paint finish requires selection of the correct flake type and size. The application process can also influence flake orientation.

When large pieces of filler, colour coat or topcoat lose adhesion with the layer below and fall off.

The temperature at which a flammable vapour will ignite in the presence of a spark or naked flame.

The time it takes for solvents to evaporate from paint to the point where consecutive coats can be applied.

Additive used to reduce or eliminate gloss from paint.

Additive used to increase the flexibility of a paint layer.  Flex agent is often used when painting over plastic or rubber surfaces, to enable the paint to move with the substrate without cracking.

Floating is when separated pigments migrate to the surface of a wet paint film.

The colour that paint appears when it is viewed at an angle rather than directly.  The colour of a finish when viewed from a side angle, other than direct.

The ability of a wet paint film to form a level, smooth surface.  Additives can be used to improve the flow of paints with high viscosity.

A tapered shaft that opens the air valve when the air gun trigger is squeezed, allowing the paint to flow.

Accelerating the paint drying process by applying heat.  Force drying can be carried out in a baking oven (for large areas and whole vehicles) or with radiant heaters for spot repairs.

A paint spraying gun that uses a paint reservoir mounted above the main body of the gun to feed the paint by gravity.

A highly pigmented colour coat used to improve hiding.  A ground coat is generally followed by a translucent coat of the same colour.

A mist coat of a different colour applied to primer before sanding.  As sanding progresses, the guide coat will remain longer in low spots and imperfections to indicate where further sanding is required.

When a finger drawn lightly across the surface doesn’t leave a mark and the paint is ready for another coat.

The second component of a 2K filler, primer or paint.  When hardener is mixed with the main component a chemical reaction starts an irreversible curing process.  It is important that hardener should be added in the correct proportion and thoroughly mixed to ensure a complete and satisfactory cure.

A paint film’s resistance to surface damage.  Paint hardness is measured by 14 of the hardnesses used for graphic pencils – 6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, and 6H.

The ability of a colour coat to mask the colour or pattern of an underlying surface.  Measured by determining the minimum thickness at which a film will completely obscure a black and white pattern, hiding power may differ between wet and dry coats.

Paints containing more than 50-60% solids by weight.  Solids are defined as pigments, resin or film formers. Paints with a high solids ratio contain lower levels of volatile organic compounds (VOC).

Paints containing higher levels of pigment than resin.  Paints with higher strength or pigment concentration are more effective at hiding.

Spray equipment delivering paints at pressures of 10psi or lower at the air cap combined with a greater volume of air.  HVLP systems minimise paint wastage, mess and VOC emissions.

A base coat’s resistance to absorption of the top coat.  If the top coat is absorbed by the base coat its evenness of tone and gloss are affected. A base coat with good holdout properties is therefore important.

The amount of water in the air, either as a suspension (vapour) or precipitation (droplets).  Absolute humidity is the amount of moisture in one cubic metre of air in the given conditions.
Relative humidity is the amount of moisture in the air compared with the saturation point – the point at which the air can no longer hold the moisture as a suspension and precipitation occurs.
Humidity will greatly affect the drying time of all paints, and water-based paints in particular.

An evenly-spaced increase in length, quantity, weight or volume.

Infra-red is the part of the colour spectrum immediately below the visible light range.  An infra-red lamp is a source of heat that can be used to cure paint.

The ability of two coats of paint to stick to each other.

A failure of intercoat adhesion can generally be attributed to

  • incompatibility between the two coats
  • contamination in or on the surface of the first coat
  • overcuring of the first coat

A hardening agent widely used in two-component (2K) fillers, primers, colour coats and top coats.

Jelling occurs when paint starts to dry or cure before application, rendering it unusable.

A quick-drying combination of solvents and nitrocellulose or acrylic resins.  Although providing a thicker coat than enamel, lacquer remains susceptible to attack by similar substances and the solvents used in their formulation.

Reduction of colourant or mass tone intensity by adding white or silver pigments.  Let down allows a coat’s cast and strength to be seen.

When solvent soaks into a soluble undercoat and swells, causing the topcoat to wrinkle.

A paint film with low build is too thin to protect the substrate or withstand environmental conditions.

A final coat of paint, applied at a lower air pressure.  A low-pressure coat is used to blend a new paint coat with an old or to create a more uniform finish.

Paint spraying systems that deliver lower volumes of paint at a lower pressure.  LVLP systems deliver a highly atomised spray and waste less material, making them ideal for lacquers and clear coats.

Covering parts of a vehicle to protect them from overspray.  Masking tape is a low tack pressure-sensitive tape, often made from crepe paper, that adheres temporarily to most surfaces and can be removed without leaving residue.  This can be used to create sharp spray lines or to hold down the edges of plastic or paper sheets to mask larger areas.

The appearance of a paint colour before it has been diluted or thinned.

A document that contains information on the contents of a material, highlights potential health, safety and environmental hazards and advises precautionary measures.

Paint containing small flakes of aluminium or mica pigments.  Metallic colours are increasing in popularity for use on vehicles and are now more commonly seen on commercial vehicles as well as cars.

A visual effect where colours only match under certain light sources or viewing conditions.

A solvent used in some paint reducers and thinners.

A pigment used as tiny flakes to create a shimmering effect in paint films.  Mica is a shiny silicate mineral with a layered structure, found as minute scales in granite and other rocks, or as crystals.

Equipment used to apply paint electrostatically.  A mini bell contains an electrically-charged spinning disk.  As paint is applied to the disk it is atomised through centrifugal force.

A fine layer of thinly-sprayed paint is applied before the main coat.  If a mist coat is applied and allowed to tack-off slightly it provides better adhesion for the main coat.  A mist coat can also be used as a guide coat.

The proportion to which ingredients are blended to make a spray-ready paint.  For example, a mix ratio of 4:1 requires 4 parts of one ingredient to 1 part of another. Mix ratios can be by volume or by weight.

Uneven distribution of metallic or mica particles in a paint film, resulting in a blotchy effect.

Mottling can be caused by

  • insufficient flash-off time between the base coat and clear coat
  • a basecoat that is applied too wet
  • holding the spray gun to close to the surface or using an uneven spray pattern
  • using the wrong thinner or not mixing the paint uniformly

A lacquer made with natural cellulose resin from cotton.

Solvents that will not react with sunlight to cause ozone or smog.

Acronym of original equipment manufacturer.  OEM coatings are formulated by or on behalf of the manufacturer to exactly match the appearance and performance of the original coatings.

An uneven or dimpled irregularity in a paint surface, closely resembling the peel of an orange.  Orange peel in paint may have a slight texture, or may feel smooth to the touch while looking textured.  It is commonly caused by incorrect spraying techniques.

An orientation coat is used on metallic colours as the final colour coat to even out the metallics (prevent mottling and striping).

Paint spray that travels beyond the limits of the painted area.  Overspray can be reduced by using an electrostatic spraying technique, but masking should be used to protect surrounding areas that do not require painting.

Repainting of an entire car, in contrast with spot repairs.  While spot repairs save time and money where damage is confined to small areas, overall painting is preferable if it is less localised.
All car paint and clearcoat fades, picks up small chips and becomes dull over time. Overall painting can restore the car to a ‘brand-new’ look with no slight changes between the original and repainted panels.

Partly extending a new coat over the surrounding original coat to make it easier to blend the two during the polishing stage.

To add more thinner or reducer to a paint than would normally be required.  Paint is sometimes deliberately over-reduced to lower its viscosity, help to blend it in or to create a special paint effect.

Chemical reaction between oxygen and another substance.  Some paints cure by oxidation.  Oxidation can also cause paint to fail over time, and cause rust on ferrous metals and tarnishing on non-ferrous metals such as aluminium.

When solids settle to the bottom of a paint can or spray gun reservoir.

Loss of adhesion between two coatings.

Solvents that will react with sunlight to cause ozone or smog.

Particles added to paint to influence colour, opacity, corrosion resistance, strength, etc.

Pin-prick sized imperfections in a coating.  Pinholing is caused by air bubbles or solvents trapped within the coating.

Imperfections caused by excessive pressure, friction or heat during polishing.  Polish marks are particularly prevalent with machine polishing and may take the form of swirls.  They can be prevented by applying minimum pressure, reducing the rotational speed, constantly moving the polisher across a surface and not letting the polishing pad dry out or get too warm.

A paste-like substance used with a polishing pad to remove minor imperfections from the surface of clearcoat and create or restore a high-gloss appearance.  While polishing compound is similar to cutting compound it is far less aggressive.

The length of time in which two-component materials such as body filler and 2K paints are usable. Also known as working time or usable life.

When sprayed paint dust particles land on the painted surface in the form of a powder.

A sealed paint container with a compressed air infeed that forces the paint along a hose to a pressure-feed spray gun.  A pressure pot can hold a larger volume of paint than the reservoir on a gravity feed or suction feed gun, making it more suitable for larger painting projects.

A paint spray gun connected to a separate pressurised paint container (pressure pot) by a hose, rather than having an integral paint reservoir.  A pressure-feed gun is more versatile than a gravity feed or suction feed gun as it is lighter, can be sprayed from any angle without affecting the paint feed, and with a higher-capacity paint reservoir, can be used for larger scale paint jobs without refilling.

The three colours that combine together to make any colour – magenta (red), cyan (blue) and yellow.  While the three primary colours will make any colour, other colours such as black and opaque white are generally used in colour mixing. Black contains a much higher level of pigment intensity and is needed to achieve darker shades, while opaque white helps improve hide.

A coating applied to bare substrates and difficult materials before applying a colour coat.  Primer helps to improve adhesion between the bare substrate and the colour coat, increase corrosion resistance, and hide contrasting colours.

A primer that additionally seals old painted surfaces to prevent them from absorbing colour coat.  An undercoat which improves adhesion and colour of the topcoat, and which seals old painted surfaces that have been sanded; usually does not require sanding.

A primer with high-build characteristics, designed to fill imperfections and to be sanded to a smooth finish.

Small wrinkles in the surface of a paint film, caused by the use of incompatible additives.

A 1k putty is used to spot-repair small areas.  Spot putty (also called knifing putty) is applied with a plastic or metal spatula and sanded smooth. Unlike epoxy car body fillers, its single-component formula means it doesn’t need to be mixed before use, but neither does it have the same adhesion, strength or chemical resistance.

The dispersion of metallic or mica flakes with no specific pattern.  Random orientation means that the flakes are not all aligned in the same direction or on the same plane. If that were the case, the metallic effect would only be evident when the surface is viewed from one direction.  With random orientation, different flakes reflect light as the position of the surface or viewer change, creating a metallic or sparkling effect.

A solvent used to reduce the viscosity of a paint or clearcoat so that it is sprayable.

To replace or repair a painted surface.  Refinishing either follows car body repair or is to restore damaged paintwork and generally involves partial or full replacement of the primer, colour coat and clearcoat.

The application of measured heat to melt and restructure slightly damaged paintwork.  Slight marring of paintwork can occur from (for example) the acid in bird droppings etching the surface. Providing the paintwork isn’t too old or the damage too severe, reflow may restore the paint without respraying.

A solvent used to slow down evaporation from paint film.  High ambient temperatures and airflow can accelerate evaporation, which can cause problems.  Using retarder can rectify this, although too much retarder can also affect the coating’s performance and characteristics.

Excessive paint application to a vertical surface will cause the paint to sag.  Sagging happens not only immediately after excessive paint has been applied (and before solvent evaporation has increased the paint’s viscosity) but also during the baking process.

Slight and even microscopic marks left in the surface of filler, primer and topcoats.  Sanding marks may remain invisible until the final gloss coat is applied when they will reflect light differently to the surrounding surfaces.  To prevent sanding marks from spoiling the finished effect, sanding should be carried out in progressive steps of grit from coarse to fine (not straight from coarse to fine).  Dry guide coat can also be used to highlight sanding marks during the sanding process to ensure they are all eliminated before the next coat is applied.

A coating applied before a topcoat to enhance adhesion, increase hold-out and provide an even surface for the topcoat.

A secondary colour is the combination of two primary colours to create a third colour.  For example, magenta (red) and cyan (blue) mixed together make purple.

A gritty appearance caused by very small, insoluble particles in the paint.

A variation of a colour on the light-dark spectrum.

A paint-spraying gun that uses airflow over an opening to draw paint up a tube from a reservoir mounted below the main body of the gun.  While gravity-feed guns are increasing in popularity, siphon-feed guns have their advantages, including an uninterrupted view of the spray area from above and behind the gun.

Paints that contain no metallic pigments.  Solid colour paints are more opaque than metallic paints, are less expensive, easier to match and apply and offer better hiding characteristics.

The part of a paint formulation that does not evaporate.

A liquid chemical such as a volatile organic compound (VOC) that will dissolve other components in a paint or other coating.  Solvents are used to reduce the viscosity of paint to an even consistency so that it will easily atomise and flow across the surface.  Once the paint has been applied to the surface the solvents evaporate, leaving the solids as the dry paint film.

Solvent-based chemicals used to clean, degrease and decontaminate surfaces before treatment.

Blisters that form in a paint film due to trapped solvent.  If solvent popping occurs, the paint film should be left to dry and cure completely and then sanded down to a stable surface.

Long cracks in a paint film.  Splitting may be caused by excessive use of hardeners, insufficient flash time between coats, force-dried or too-thick undercoats, incorrectly mixed paint or exposure to extreme temperatures or moisture.

Repairs to small areas, only requiring localised filling and repainting.  Spot repairs are preferred if the damage is localised, as only a small area needs to be refinished. Where there is damage to several areas of the car body, overall painting may be preferable.

The shape of the area made by the spray as it touches the paint surface.  The spray pattern can be adjusted on a spray gun – and some paint aerosols – from a small, round spot to a large, flat oval.  The required spray pattern will depend on the nature and size of the refinishing.

A resin-containing solvent that reduces the viscosity of a colour coat to help control metallic pigments and recoat times.

The hiding ability of a colour coat.

Variation in the colour intensity of a colour coat due to poor spraying technique.  Stripping or banding can occur if the spacing between parallel passes is inconsistent, leading to overlap or gaps; if the spray gun is held too close or not perpendicular to the surface; if the spraying viscosity or pressure is incorrect; if the flash time is too short or the paint is applied at the wrong temperature; and if the wrong thinners are used.

An easily-sanded paint that is used to fill surface irregularities prior to a final application of colour coat.

The stickiness of a paint film during the drying process.  The drying speed of an air-drying paint can be determined by the time it takes to reach a tack-free state.

A lint-free cloth coated with a slightly sticky substance, used to remove dirt, dust and lint from a surface before painting.

A mist coat that is left to become slightly tacky before a full coat is applied, enhancing the adhesion of the paint.

The point in the drying process when a paint is no longer tacky.

Paints that when dry can be softened with heat and return to their original hardness as they cool.  Lacquers are examples of thermoplastic paints. With thermoplastic paints, repairs can sometimes be carried out without having to recoat if the paint is heated first.

Paint that requires heat to harden and cure.  Enamels and urethanes are examples of thermosetting paints.

Any solvent added to paint or lacquer to reduce its viscosity to a sprayable consistency.

A thixotropic substance has a semi-solid consistency until mechanical disturbance (rapid shaking, brushing, etc.) turns it into a liquid.

Pure toner used to change paint colour.  Compared with paint mixing, adding toner to paint changes the colour without substantially increasing the volume.

Changing a paint colour by adding tint.

A highly opaque white pigment.  Titanium oxide is commonly used to increase the brightness, opacity and hiding power of white and light-coloured paints.

Tinting medium made with ground pigments, solvent and resin.

The final coat of paint or lacquer applied to a surface.  A clear topcoat protects and provides both gloss and depth of colour to underlying colour coats, and is often applied in several layers.

The percentage of sprayed paint or lacquer that is applied to the required surface (i.e. not lost to overspray or drift).  Painting systems such as low volume low pressure (LVLP) and electrostatic paint application have high transfer efficiency.

A multi-component coating applied to the cargo area of a truck to increase durability and chip-resistance.  This durable coating has many uses beyond truck beds, where surfaces require protection from mechanical, chemical and saline damage.

A filler, primer, paint or lacquer which requires mixing with a catalyst or activator before it will dry and cure.  When fully cured, two-component substances are tougher and more chemically resilient than their single-component equivalents.

Ultraviolet is the part of the colour spectrum immediately above the visible light range.  Ultraviolet radiation is present in sunlight and causes colour fading and molecular decomposition in paints.  Additives called UV stabilisers can be used to absorb UV radiation and help protect against this damage.

A primer, sealer or surfacer applied to a substrate as a first coat.  An undercoat is generally used to provide protection against corrosion and a good surface for paint adhesion.

The appearance of a paint colour once it has been diluted or thinned.  How a colour looks once it has been diluted or thinned.

Chemicals added to paint that absorbs UV radiation from sunlight.  As ultraviolet radiation decomposes the polymer molecules in a paint film, UV stabilisers are used to prolong the colourfastness and life of paint.

The components of a paint without the pigments.  The paint vehicle is a liquid combination of solvents, diluents, resins, gums, driers, etc. Some of these are removed during evaporation.

The measure of a fluid’s resistance to flow. The lower the viscosity, the more easily the liquid will flow.  The viscosity of a paint must be low enough to allow proper atomisation and flow out during spraying.

Organic chemicals that have a low boiling point at room temperature.  Volatile organic compounds are commonly used as paint solvents due to their rapid evaporation which allows paints to dry quickly.

A receptacle used to measure the viscosity of a fluid.  A Zahn cup works by recording the time it takes for the cup to empty when allowing fluid to drain through a hole in its base.