1(ix) Paint terminology and definitions

abrasion resistance

Resistance to frictional rubbing.

abrasive blast cleaning

A method of preparing surfaces before painting by the use of abrasive, such as grit propelled either through nozzles by compressed air or from wheels by centrifugal force onto the surface.

accelerator

A substance that increases the rate of reaction during film formation.

acid-resistant paint

A coating material designed to resist attack by acids under specified conditions.

acrylic

A type of synthetic polymer used as the binder for high-performance waterborne paints and sealants. Some acrylic polymers are used in auto finishes, appliance coatings, etc.

acrylic primer

A coating material, based on a waterborne acrylic resin, used to prime wood, masonry or metal.

adhesion

The degree of attachment between the film of a coating material and the substrate with which it is in contact. The latter may be another film (intercoat adhesion) or the substrate material.

aeration

The presence of air in a liquid paint.

aerosol paint

A specially formulated coating material packed under pressure in specially designed cans.

after-tack

A film defect in which the painted surface, having once reached a tack-free stage, subsequently develops a sticky condition.

ageing

Degeneration occurring in a coating during the passage of time and/or heating.

air-drying

The process by which a liquid paint film is allowed to dry under ambient conditions of temperature and relative humidity.

airless spraying

Application of paint by means of equipment consisting of fluid pump, hose and spray nozzle to produce atomisation of the paint without the use of compressed air or other propellant.

algicidal paint

A coating material incorporating special additives to discourage the growth of algae on the surface of the film.

alkali-resistant paint

A coating material designed to resist attack by alkalis under specified conditions.

alkyd

A synthetic resin used in solventborne paints. An alkyd resin is made by reacting a drying oil with a hard, synthetic material.

alligatoring

The formation of wide criss-cross cracks in a paint film. (Same as crocodiling).

aluminium wood primer

A coating material containing a portion of aluminium pigment that is used as a barrier coat to overcome bleeding from resinous woods or timber that have been treated with wood preservatives.

anti-condensation paint

A coating material designed to minimise the effects of condensation of moisture under intermittently dry and humid conditions.

anti-corrosive paint
anti-corrosive composition

A coating material used to retard the corrosion of metals and, more particularly, specially formulated to retard the rusting of iron or steel.

anti-fouling paint
anti-fouling composition

A coating material applied to the bottom of ships to discourage the growth of barnacles and other organisms.

barrier coat

A coat used to isolate subsequent coats from the preceding coats of substrate to prevent adverse physical or chemical interaction.

basecoat

The first decorative coat of a multicoat coating system.

binder

The non-volatile portion of the vehicle of a coating material that binds the pigment particles together and the film as a whole to its substrate.

biocidal wash

A solution containing fungicides and/or algicides that is applied to a substrate before painting to kill existing fungal or algal contamination or to prevent their development.

bittiness

The presence of particles of gel, flocculated material or foreign matter in a coating material.

bitumen

A viscous liquid or a solid, consisting essentially hydrocarbons and their derivatives, which is soluble in aliphatic solvents and is substantially non-volatile and softens gradually when heated.

bleaching

The total loss of colour of a coating usually as a result of weathering or chemical attack.

bleeding

Discoloration caused by migration of components from the underlying film.

blistering

The formation of dome-shaped projections or blisters in the dry film of a coating material by local loss of adhesion and lifting of the film from the underlying surface.

blocking

Unwanted adhesion between adjacent surfaces of articles that develops when these articles are left in contact.

bloom

A deposit resembling the bloom on a grape that sometimes forms on the gloss film of a coating, causing loss of gloss and dulling of colour.

blushing

A milky opalescence that sometimes develops as a film of lacquer dries and is due to the deposition of moisture from the air and/or precipitation of one or more of the solid constituents of the lacquer; usually confined to lacquers that dry solely by evaporation of solvent.

bridging

The covering over of an unfilled gap such as a crack or corner with the film of a coating material. This introduces a weakness in the coat that may lead to an eventual cracking of the dried paint.

bringing forward

In repainting. Repairing local defective areas with the appropriate coating materials so as to bring them into conformity with the surrounding areas before applying the finishing coats.

broken colour

The general multi-coloured effect brought about by the automatic merging of wet paints of various colours or by manipulation that produces random effects.

brush marks

Ridges remaining in a dry paint film after brush application.

bubbling

The appearance of temporary or permanent bubbles of air or solvent vapour or both in the applied film.

build

Thickness of dried paint film.

burning off

The removal of paint by a process in which the paint is softened by heat, such as from a flame, and then scraped off while still soft.

catalyst

A substance that increases the rate of a chemical reaction, but that remains chemically unchanged at the end of the reaction.

chalking

The process by which the binder in a dry film degrades, leaving a loose removable powder on the surface. Often applied to the presence of chalk on an exposed paint film.

checking

Breaks in the surface of a paint film that do not render the underlying coating or substrate visible.

cheesy

A state of dry intermediate between surface dry and hard dry.

chipping

The removal of paint and surface contaminants from a substrate by means of impact from a sharpened tool.

cissing

The recession of a wet paint film from a surface leaving small areas uncoated.

coat

A continuous layer of a coating material that results from a single application.

coating material

A film-forming material used to cover a substrate for protective or decorative purposes.

coating system

A coating material or sequence of coating materials applied in a specified number of coats to impart protective, decorative or other properties to a substrate.

cobwebbing

The formation of fine filaments of partly dried paint during the spray application of a fast drying paint.

cohesion

The forces that bind together into a coherent whole the particles of film.

colourant

A concentrated agent that may be added to paints to make a range of colours.

compatibility

Of a product with the substrate. The ability of a coating material applied to a substrate to give a dry adherent film without causing undesirable effects either on the properties of the product or the nature of the substrate.

consistency

The apparent viscosity of a paint under application of a shearing force.

copolymer

The product obtained from polymerisation of two different monomers.

cracking

The presence of breaks in a coating or coating system, such that the underlying coating or substrate is visible.

cratering

Residual effect of burst bubbles. (See also cissing.)

crazing

The formation of minute criss-cross cracks on the surface of a paint film.

crocodiling

The formation of wide criss-cross cracks in a paint film. (Same as alligatoring).

curing

The process of condensation or polymerisation of a material by heat or chemical means resulting in the full development of the desired properties.

de-nibbing

Removing, by rubbing with fine abrasive paper, any small particles of foreign matter that stand proud on the surface of a paint film.

degreasing

The removal from a surface, prior to painting, of mineral oils, greases and similar substances by means either of a solvent, such as trichloroethylene, or an emulsifying agent.

de/scaling

The removal of mill scale or laminated rust from steel or other ferrous substrates.

discoloration

Any change in colour of an exposed film caused by chalking, dirt collection or fading, darkening or tonal changes in the original colour.

dispersing agent
dispersant

An additive used in the manufacture of coating materials to facilitate the dispersion of the solid components in the liquid phase.

drag
brush drag

The resistance to the brush encountered when applying a coating material.

dry film thickness

The arithmetic mean of a series of dry film thickness measurements.

drying

The change of a coating material from the liquid to the solid state, due to the evaporation of solvent or physico-chemical reactions of the binding medium or a combination of these processes.

durability

A measure of the ability of a coating system to withstand the environment in service.

efflorescence

A deposit of salts that remains on the surface of masonry, brick or plaster after water has evaporated.

eggshell finish

A coated surface that exhibits diffuse reflectance, which is intermediate between a semi-gloss finish and a matt finish.

elastomer

A macromolecular material that, after substantial deformation by a weak stress at room temperature returns rapidly to its initial shape and dimensions when the stress is removed.

electrostatic spraying

A method of spraying in which an electrostatic potential difference is applied between the article to be coated and the atomised coating material particles whereby the latter are attracted to and deposited on it with minimal loss of overspray.

emulsion

A stable suspension of fine particles or globules of one liquid in another.

emulsion cleaner

Liquid wetting material for removing oily residues and detritus from surfaces prior to applying a protective coating material.

emulsion paint
latex paint

A coating material in which the medium is a dispersion of an organic binder in water.

enamel paint

Pigmented organic polymeric binders that simulate the appearance, flow, smoothness and gloss of fused inorganic coatings.

epoxy paint

A coating material based on an epoxy resin.

epoxy resin

A synthetic resin containing epoxide groups and in which the final polymer is formed as a result of a reaction taking place substantially at the epoxide groups.

erosion

Attrition of the film by natural weathering that may expose the substrate.

etch primer
washprimer
pretreatment primer
self-etch primer

A coating material often supplied as two separate components that are mixed immediately prior to application and have limited pot-life. The mixed coating material contains balanced proportions of a chromate-based inhibitive pigment, phosphoric acid and a synthetic resin binder in a mixed alcohol solvent, generally a polyvinyl butyral.

etching

Cleaning and roughening a surface using a chemical agent prior to painting in order to increase adhesion.

evaporation rate

The time taken for a given quantity of a volatile liquid, such as a solvent, to pass completely from the liquid to the vapour state under specified conditions.

exothermic

A heat generating reaction.

extender

Generally colourless, relatively transparent pigments used in conjunction with pigments to impart particular physical properties to a paint or coating.

fastness to acid

The ability to retain chemical and physical properties after exposure to acids under specified conditions.

fastness to alkali

The ability to retain chemical and physical properties after exposure to alkalis under specified conditions.

fastness to heat

The ability to retain chemical and physical properties after exposure to heat under specified conditions.

fastness to light

The ability to retain chemical and physical properties after exposure to natural or artificial light of specific characteristics and under specified conditions.

fat edge

An accumulation of a coating material in the form of a ridge at the end of a coated surface that may arise during drainage especially after dipping.

feather edging

Tapering, usually by abrading, the thickness of the edge of a dry coating system, such as the edge of a damaged area, prior to repainting.

feathering

The operation of tapering off the edges of a patch coat by laying-off with a comparatively dry brush.

felting down

The operation of flatting down the dry film of a coating material by means of a pad made of felt or similar material charged with a very fine abrasive powder and lubricated with water or other suitable liquid.

filiform corrosion

A form of corrosion under coating materials on metals characterised by a thread-like form advancing by means of a growing head or point.

filling

The application of a defective surface of a product of suitable consistency to form, when dry, a smooth surface suitable for painting.

film

A continuous layer resulting from the application of one or more coat(s) to a substrate.

film formation

The process by which coating materials, when applied to a substrate, are transformed into a cohesive layer.

finish

The final or only coat in a coating system.

fish eyes

Quasi-circular areas of substrate that are exposed through the film of a coating material that have at their centre a source of contamination.

flaking

Lifting of the coating materials from the substrate in the form of flakes or scales.

flash dry

The stage of drying at which most of the volatile solvent, or water in a water-thinnable paint, has evaporated and which is often characterised by a marked change in appearance.

flash point

The minimum temperature of liquid at which the vapours given off are sufficient to form a flammable mixture with air under specified conditions of test.

flash-off

The evaporation of sufficient of the solvents in a sprayed coat that is allowed to occur before proceeding either with the application of another coat or with stoving.

flashing

The development of patches glossier than the general finish that develop in the film of a coating material, especially at joins or laps in the coating.

flatting down
rubbing down

Abrading the surface of a dry coating material with fine, dry or wet abrasives to produce a smooth dull surface.

flexibility

The degree to which a coating material is able to conform to movement or deformation of its supporting surface without cracking or flaking.

flow

The degree to which the wet film of a coating material can flow out during and after application to produce a uniform smooth surface.

flow coating

The application of a coating material either by pouring or by allowing it by flood coating to flow over the object to be coated and allowing the excess to drain off.

flushing

The application of coating material to the interior of hollow articles by introducing the coating material and subsequent draining off the excess.

force drying

A technique in which the drying of the film of a coating material is accelerated by exposing it to a temperature higher than ambient but below that normally used for stoving materials.

frosting

A translucent, finely wrinkled surface effect that occurs during drying and which may be produced deliberately to mask imperfections on the substrate or to achieve other desirable visual properties.

fugitive

A description of colouring matter that readily suffers partial or total loss of its original colour on exposure to light or weather.

full coat

The thickest coat that may be applied in a single application to give a film which, when dry, is free from defects.

full gloss
gloss finish

The film of a coating material that, when dry ,has a smooth almost mirror-like surface.

fungicidal paint

A coating material that discourages the growth of surface moulds on the dry film. This property is normally conferred by the use of special additives, although certain pigments may themselves contribute to the fungicidal property of the paint.

galvanising

A process whereby suitably pretreated steel is given a coat of zinc by immersion in the molten metal.

gelling

Deterioration of a paint by the partial or complete changing of the medium into a jelly-like condition.

glaze coat

A translucent or transparent coating material, sometimes coloured, applied thinly with the object of enhancing, but not obscuring the ground coat.

glazing putty

A type of putty based on an inorganic filler and linseed oil used for fixing glass panes in wooden frames.

gloss

The reflecting characteristics of the surface of a coating or coating system.

grinning through

The showing through of the substrate due to the inadequate hiding power of the coating material.

grit blasting

Abrasive blast-cleaning using grit as the particulate material. Grit may be of alumina, waste metal slags, iron or steel.

hair cracks

Fine cracks in the topcoat of a finishing system.

hardener

A cross-linking agent used to cure a resin or paint system.

hiding power
covering power opacity
obliterating power

The degree to which a coating material obscures the colour of the substrate to which covering power opacity it is applied.

high build coating

A paint that enables the application in one coat of a relatively thick film of paint without sagging or running.

high solids

A term applied to coating materials in which, by the choice of suitable ingredients, the content of volatiles present is kept to a minimum, consistent with the maintenance of satisfactory application properties.

highlighting

Emphasising or creating the impression of relief by making certain parts of a finished surface lighter than the general colour of that surface.

hold out (1)

The ability of the film of a coating material to dry to its normal finish on an absorptive substrate.

hold out (2)

The relative tendency of different undercoats to affect the gloss when coated with a finishing coating material.

holidays

Defects characterised by a film having areas of insufficient thickness even to the point where parts of the surface may remain uncoated.

hot spot

Localised area of high absorbency.

hot spraying

The spraying of a coating material that has been reduced in viscosity by heating rather than by addition of solvents. By such a process it is possible to apply coating materials with higher solids contents and, therefore, obtain better build.

hungry surface

An abnormally absorptive surface requiring an excessive amount of paint to give a continuous film.

hydrophilic

Attracted to water.

hydrophobic

Repelled by water.

illuminant

The light that is emitted by a light source or that falls on a surface.

inert pigment

A pigment that remains relatively inactive or chemically unchanged in paints under specified conditions.

inhibitor

A material used in small proportion to slow a chemical reaction.

intumescence

Foaming or swelling of a coating as a result of application of heat.

isocyanates

A class of organic compounds embodying the NCO group that react with polyesters and polyethers to form polyurethane resins.

ladders

In paint films. A ladder-like pattern due to a miss in laying off paint that allows a strip of brushmarks in the opposite direction to remain undisturbed and visible.

lap

The zone where a coat of paint extends over an adjacent freshly applied coat.

latex

Originally a natural rubber latex; now also applied to dispersions of various synthetic resins.

laying off

The final operation in the brush application of coating materials, whereby unevenness in the film surface is reduced by light brushstrokes.

lead-based paint

A coating material that contains lead-based pigments in substantial quantities.

leafing

The action involving the floating and slight overlapping of certain metallic and other pigment particles, in the form of thin flakes, in the surface of the film of a coating material.

levelling

The flowing out of a coat of wet coating material to give a smooth surface.

lifting

Softening, swelling, or separation from the substrate of a dry coat as the result of the application of a subsequent coat.

lightness

The proportion of light that a surface reflects, irrespective of hue and saturation.

linseed oil

The drying oil obtained from the seeds of the flax plant Linum Usitatissimum.

loose scale

Mill scale that has been loosened by rusting and may be lifted from the steel surface by means of a scraper.

masking

Application of a temporary cover to that part of a surface that is not to be painted.

mastic

A generic term used to describe a plastic filler, stopper, putty, or adhesive.

matt

The description of a painted surface that scatters or absorbs the light falling flat on it so as to be substantially free from gloss or sheen when viewed at any angle.

metallic paint

A coating material that upon application gives a film with a metallic appearance. The effect is normally produced by the incorporation of fine flakes of metals such as copper, bronze or aluminium, that are non-leafing or leafing; the latter giving a more lustrous appearance.

metameric match

A match in colour between paints under one illuminant but not under others.

milkiness

A whitish or translucent appearance in the normally transparent film of a varnish.

mill scale

The layer of iron oxides produced during the hot rolling of steel.

mist coat

A thin coat of paint, not intended to form a protective film, but to enhance the adhesion of subsequent coats.

moisture-curing coating material

A coating material in which the film cross links and hardens when exposed to atmospheric moisture.

mud cracking

A network of deep cracks that form as the film of a coating material dries, especially when it has been applied to an absorbent substrate. Mud cracking is associated primarily with highly pigmented waterborne paints.

multi-colour paint

A coating material, usually for application by spraying, to produce a mottled or flecked appearance in two or more colours.

nibs

Small pieces of foreign matter, pieces of gelled coating material, coagulated medium, etc. that project above the surface of the film of a coating material.

non-volatile content

The quantity of material remaining after removal of the volatile constituents of a paint; may be expressed by mass or volume (volume solids).

orange peel

The uniform pock-marked appearance, in particular of a rolled film, resembling the peel of an orange due to the failure of the film to flow out to a level surface.

organic pigment
pigment-dyestuff

A coloured pigment, insoluble in water but sometimes partially soluble in organic solvents, based on an organic compound sometimes with an inorganic component physically or chemically incorporated.

paint

A pigmented material that, when applied as a liquid to a surface, forms, after a time, a dry adherent film.

paint remover

A material which, when applied to a coated substrate, softens the coating material so that it can be removed easily.

peeling

The spontaneous removal in ribbons or sheets of the film of a coating material from the substrate due to loss of adhesion.

pencil hardness test

A method for assessing the hardness of the dry film of a coating material in which pencils of increasing hardness from 4B to 6H are pushed in turn across the surface until an indentation is obtained.

petrifying liquid

An obsolescent product, consisting of a dilute emulsion of drying oil and/or resins in water; formerly used as a sealing coat before the application of an oil-bound water paint to a porous substrate.

phosphating
bonderizing
phosphate treatment

Pretreatment of steel or certain other chemical solutions containing metal phosphates and phosphoric acid as the main constituents, to form a thin, inert, adherent, corrosion-inhibiting phosphate layer that serves as a good base for subsequent paint coats.

phosphorescent paint

A luminous paint containing pigments (phosphors) that absorb energy at one wavelength and emit it over a period in the form of light, at a longer wavelength in the visible spectrum.

picking up

The joining up of a wet edge.

pickling

A process by which rust and mill scale are removed from steel by immersion in an acid containing inhibitor followed by thorough washing and drying before painting.

pigment

A substance, usually in the form of fine particles, that is practically insoluble in the medium and is used because of its optical, protective or decorative properties.

pigment binder ratio

The ratio, expressed as mass/mass, of the total pigment (white and/or coloured pigment plus extender) to the binder in a coating material.

pigment volume concentration

The concentration, by volume of a pigment in a paint or in a mill-base or in a dry film, usually expressed as a percentage of the non-volatile component.

pinholing

The formation of minute holes in the wet film of a coating material that form during application and drying due to air or gas bubbles in the wet film that burst, giving rise to small craters that fail to coalesce before the film has set.

pink primer

A primer based originally on white and red lead pigments. Now used loosely to describe wood primers, pink in colour, but based on pigments other than lead.

pitting

The formation due to corrosion of small cavities in a metal substrate.

plaster primer

A primer with resistance to alkali that is used for priming plaster, cement and renderings.

pock-marking

The formation of irregular and unsightly depressions that form during the drying of a coating material.

polymer

A substance, the molecules of which consist of one or more structural unit(s), repeated many times.

popping

Of a film. The formation of eruptions in the film of a coating material after it has become partially set so that the craters remain in the film.

pot life

The period, after mixing the components of a two-pack paint, during which the paint remains usable.

powder coating material

A coating material, usually containing pigments, resins and other additives, that is applied in the form of a powder to a suitable substrate after cleaning to give protection in the period before and during fabrication.

pretreatment

The chemical treatment of unpainted metal surfaces prior to painting.

primer

The coating material used to provide a priming coat.

primer surfacer

A pigmented material, essentially a thin filler and/or sealer, designed particularly for smoothing up slightly uneven substrates in preparation for the subsequent application of a coating system.

priming coat

The first coat of a coating system applied to a prepared surface.

print resistance

The ability of a coating material to resist taking on the imprint of another surface placed on it under normal conditions of practical use.

pulling

Excessive resistance to the movement of a brush during the application of a coating material due to its viscous nature.

pulling up

The softening of a coat, by the application of a subsequent coat, to such an extent that it makes brush application difficult and in extreme cases causes an objectionable intermingling of the two coats.

putty

A dough-like preparation that is applied by a knife and that normally hardens on exposure to air.

radiation curing

The drying and hardening of coating materials by exposure to radiant energy. Specifically the term implies activation of a chemical cure by ultraviolet radiation or electron beams.

radioactive paint

A luminous paint containing radioactive materials that cause the phosphors to emit light.

rag rolling (1)

The process of forming, in a scumble or glaze coat over a painting ground, a textured or variegated pattern by rolling a rag or washleather over the surface.

rag rolling (2)

Printing a pattern on a dry coated substrate by means of a rag or washleather charged with colour. The rag is crumpled in the form of a roller to produce the pattern.

resistance weld primer

A coating material that is applied to an unpainted metal substrate for temporary protection against corrosion and that does not have to be removed prior to resistance welding.

retarder

A substance added to slow down a chemical or physical change. A slowly evaporating solvent may be added to a coating material to delay the set of the film after application and to improve the application properties or to give a better film, such as one with improved flow.

roller coating

A process by which a coating material is applied mechanically to sheet metal that is passing between horizontal rollers, one of which is kept coated with a film of liquid coating material.

sagging

Excessive flow of paint on vertical surfaces causing imperfections with thick lower edges in the paint film.

sanding

An abrasive process used to level a coated surface prior to the application of a further coat.

sanding sealer

A coating material that has the special property of sealing or filling but not necessarily obscuring the grain of a wooden substrate. When dry the surface is suitable for sanding.

saponification

A defect resulting from attack on a binder by alkali.

scuffing

Very light abrading with a fine abrasive paper of a dry coat prior to application of a subsequent coat.

scumble glaze

A transparent preparation used in the scumbling process.

scumble stain

A semi-transparent stain for application over an opaque ground work of paint.

sealant

An organic or silicone-based material capable of providing a flexible, impermeable barrier between two surfaces.

sealer

A product used to seal substrates to prevent materials from bleeding through to the surface, to prevent reaction of the substrate with incompatible topcoats or to prevent undue absorption of the following coat into the substrate.

semi-gloss finish

A painted surface that gives a level of gloss between an eggshell finish and a full gloss.

settling

The sedimentation of solid constituents, such as pigments and extenders, from a coating material while standing in a container.

sheen

A finish that appears to possess gloss when seen at glancing angles to the surface, but which, when viewed at an angle normal to the surface, appears matt.

shelf life

The period of time a paint may be stored in sealed unopened containers without the paint showing any significant deterioration in quality.

sherardising

A method of coating ferrous articles by heating for several hours in intimate contact with zinc dust.

shop primer

A protective coating material for application to a component that is subsequently to be finished on site.

skinning

The formation, in a container, of an oxidised film on the surface of a paint.

solids content/solids

The mass, expressed as a percentage of the original mass of coating material, which, under specified conditions, remains to constitute a dry film.

solvent

A liquid, single or blended, which is volatile under normal drying conditions and in which the binder is completely soluble.

solvent cleaning

Removal of oil or grease from a surface prior to painting by the action of a suitable solvent.

solventborne material

A material that is dispersed or dissolved in suitable organic solvents.

solventless paint

An organic coating material containing no volatile thinner.

spatter paint

A coating system that produces a textured surface, usually in the form of large spots or droplets and usually includes a ground coat of the same material or colour.

spirit

In the paint industry, this term is somewhat loosely used, but generally refers to commercial ethyl alcohol normally sold as industrial methylated spirit.

spirit lacquer
spirit varnish

A lacquer based on a solution of resin(s) in industrial methylated spirits.

spiriting off

The final operation in a French polishing process by which the last traces of vegetable oil are removed by drawing a rag, dampened with methylated spirit, rapidly and repeatedly over the surface.

split spray

An undesirable asymmetrical spray pattern giving rise to the application of bands of paint of uneven thickness.

spotting in
spot finishing

The correction, after flatting down, of small defective areas in sprayed coating materials.

spraying

A method of application in which the atomised coating material is directed on to the substrate to be coated.

spreading rate

The area, in square metres, covered by one litre of paint at a nominated dry film thickness.

stabiliser

A substance added, usually in small proportions, to retard undesirable chemical or physical changes.

stain
oil stain
spirit stain
water stain

A solution or suspension of colouring matter in a vehicle, designed to colour a substrate by penetration without hiding it. True stains are classified as water stains, oil stains and spirit stains according to the nature of the vehicle.

starved surface

A substrate that by virtue of its surface structure causes a visibly deficient film of a coating material to the extent that it is not sufficient to provide a uniform continuous coat.

steam cleaning

Removal of surface contaminants by the action of steam jets.

stippling (1)

Evening out a coat of paint and removing brushmarks and other imperfections immediately after application by systematically dabbing the surface with a stippling brush.

stippling (2)

Producing a speckled or textured effect, either by applying spots of a different colour or by disturbing the surface of the paint coat, such as with a stippling brush or rubber stippler.

stopper

A stiff paste used for filling holes, cracks and similar defects in surfaces.

stoving

The process of drying and hardening a coating material by heating either:

(a) by a convection oven in which the heat transfer takes place largely, but not exclusively, by convection; or

(b) by radiant heat, in which the heat transfer takes place largely, but not exclusively, by radiation. This is often known as infra-red stoving.

streaking

The formation of irregular lines or streaks of various colours in a paint film caused by contamination or improper incorporation of colourant.

stripping

The removal of old paint, distemper or other coating materials with or without the aid of solvents or heat.

substrate

The surface to which a coat or paint or varnish is applied.

sugar soap

A product that, after mixing with water, gives an alkaline solution for washing down sound paintwork before painting.

surface profile

The micro-roughness of a surface, generally expressed as the average height of the major peaks relative to the major valleys.

surfactant
surface-active agent

A substance that has the fundamental property of reducing the interfacial tension between a solid and a liquid or a liquid and air.

tack

Slight stickiness of the surface of the film of a coating material, apparent when it is pressed with a finger.

tack-free

Free from tack, even under pressure.

textured paint

A coating material that by its composition or method of application gives a textured finish.

thermoplastic
roadmarking
composition

A coating material consisting of pigments, extenders, mineral aggregates and resins road marking that is applied in the molten state as markings on roads.

thinner

A volatile liquid, single or blended, added to paint to facilitate application by lowering the viscosity.

thinning ratio

The recommended proportion of thinner to be added to a coating material to render it suitable for a particular method of application.

thixotropic paint

A coating material that, while free-flowing and easy to manipulate under the brush, sets to a gel within a short time when it is allowed to remain at rest.

throwing power

A measure of the ability of a coating material to be applied by electrodeposition in the deep and semi-enclosed regions of an object, such as within the box sections of a motor vehicle.

tie-coat

A coat applied to a previous coat to improve the adhesion of subsequent coats.

tint-base

The basic paint to which colourants are added as required to make a wide range of colours.

tinter

A coloured pigment or pigments dispersed in a medium compatible with paint vehicles, added in relatively small proportions to already prepared paints to modify their colour.

titanium dioxide pigment

One of a range of white pigments, widely used in coating materials, that are based on titanium dioxide in two crystalline forms: anatase and rutile. The two forms differ in their effects on hiding power and weathering resistance; these effects may be modified by treatment, such as with silica or alumina.

toner

An insoluble salt of an organic dye.

tooth

A property of the dry film of a coating material that contains a proportion of relatively coarse or abrasive pigment that improves the rubbing properties and also the adhesion of subsequent coats.

touch dry

The state of drying when slight pressure applied by a finger does not leave an imprint or reveal tackiness.

transparent iron oxide

A red oxide pigment that colours a coating material with minimal effect on its transparency.

two-pack paint

A coating material that is supplied in two parts that have to be mixed in the correct proportions before use. The mixture will then remain in a usable condition for a limited time.

undercoat

The coat or coats applied to the substrate after filling, priming, etc. or after the preparation of a previously painted surface and before the application of a finishing coat.

universal tinter

A multi-purpose tinter that can be used both with organic solvent-thinned paints and with water-thinned paints.

vapour degreasing

Removal of grease and oils from metallic components by exposure to the vapour of a suitable solvent prior to pretreatment or painting.

varnish

A transparent coating material based essentially on resins and/or drying oil and solvent.

vehicle

The liquid portion of a coating material in which the pigment is dispersed.

viscosity

The resistance of a fluid to flow.

volatile matter

The substances that are released from coating materials by evaporation under specified conditions.

volatile organic compounds

Solvent emissions from the wet film while drying that evaporate into the atmosphere.

volume solids

Expressed as a percentage and means the volume of solid material contained in the paint that forms the dried film of the paint after application. The remainder of the paint evaporates.

washability

The ease with which soiling can be removed from a coated surface by washing.

waterblasting

Cleaning of a surface with a jet of water, with or without the assistance of compressed air, which may contain certain additives, such as corrosion inhibitors and an abrasive.

waterborne paint

A paint in which the pigment and binder are dispersed or dissolved in a continuous phase that consists essentially of water.

water-dispersible paint

A paint consisting of a stable dispersion in water with little or tendency to separate during storage.

water-spotting

The spotty appearance of the film of a coating material, caused by drops of water on the surface that remains after the water has evaporated; the effect may or may not be permanent. Water spots usually appear lighter in colour than the surrounding paint.

weathering

The exposure of a coating or coating system to an atmospheric environment.

webbing

The development of wrinkles, often in a well-defined pattern, in the film of a coating material during drying due to the irreversible swelling of a partially dried surface skin.

weld-through sealer

A mastic gap-filling material that is applied, prior to welding, to unpainted metal substrate for non-pressure sealing purposes and which does not prevent the making of a satisfactory weld.

welding primer

A coating material that is applied to an unpainted metal surface for protective purposes that does not have to be removed prior to acetylene welding and does not prevent the making of a satisfactory weld.

wet edge time
wet edge
live edge

The period of time during which the physical condition at the boundary of the film of a coating material allows the same product to be applied to an adjacent area and to be blended imperceptibly with the existing film.

wet-on-wet

A technique where by a further coat is applied before the previous one has dried and the composite film then dries as a whole.

wetting

The ability a vehicle possesses to spread uniformly and rapidly over the surface of pigment particles.

whip blasting

Light abrasive blast cleaning.

whirling

The centrifugal removal of excess paint from articles that have been coated by dipping.

white rust

Term loosely used to describe corrosion products of certain non-ferrous metals.

windowing

In coating materials for dipping. The formation of a film of the coating material across holes pierced in the component being painted.

wire enamel

A coating material, usually unpigmented, applied to copper wire to confer insulating properties when the wire is subsequently used in electrical equipment.

wrinkling

The development of wrinkles in the film of a coating material during drying, usually due to the initial formation of a surface skin.

yellowing

The development of a yellow colour on ageing.

zinc dust

Finely divided zinc metal used as a pigment in protective coating materials for iron and steel.

zinc phosphate primer

A coating material containing zinc phosphate pigment for application to steel to inhibit corrosion.

zinc rich primer

An anti-corrosive coating material for iron and steel incorporating zinc dust in a concentration sufficient to give cathodic protection whereby the dry film is electrically conductive, enabling the zinc metal to corrode preferentially to the substrate.