A
Abrasion: Gradual wearing away due to mechanical action, e.g. foot traffic, scrubbing, etc.
Abrasive blast cleaning: Pre-treatment to remove rust, millscale and ingrained dirt from surfaces by means of compressed air and abrasives (sand or shot).
Acid: Group of chemicals with low pH and strong corrosive action. React with alkalis violently.
Acid Curing: Curing process through addition of acidic compounds. Two pack clear or pigmented finishes are mainly used on wooden floors and furniture.
Acid Resistance: Ability to with stand attack by acid without film breakdown.
Acrylic Resin: Water white synthetic resin produced by polymerisation of certain acrylic esters. Available as solid resin, as solution in organic solvents and in emulsion form.
Additive: Group of chemical ingredients used in minor proportions in paint in order prevent certain problems or to impart specific properties.
Adhesion: Property of a coating to adhere or bond onto a surface. Surface roughness and absence of oil, grease and wax promote adhesion. Chemical pre-treatment is sometime essential to ensure good adhesion of coatings to certain metals.
Air Drying: Drying taking place at ambient temperature and in full contact with air.
Airless Spraying: Spraying process without the use of compressed air. The material is being atomised and conveyed by pumped pressure, resulting in greater penetration, improved adhesion, large material savings and a better spray pattern free of turbulence. Very viscous materials can be applied by this process.
Algae: Micro organism, classified as plant, occurring in fresh or salt water and moist ground.
Aliphatic: A straight, open carbon chain configuration in organic compounds, e.g. Paraffins.
Alkali Resistance: Ability to withstand attack by alkali without film breakdown, specifically saponification.
Alkyd Resin: Synthetic resin based on phthalic anhydride and a polyol, usually modified with oil. Also available modified with other materials, e.g. styrene, acrylic, phenolic resin.
Anti-Corrosive: To prevent corrosion, e.g. the rusting of metals. Anti-corrosive metal primers are essential to protect metal as first coat.
Anti-Fouling: Preventing marine growth on ship’s bottoms.
Application: The actual process of applying a coating to a surface. A variety of application methods is in use, e.g. blushing, spraying, dipping, roller application, etc.
Aqueous: Water based. In this type of coating the solvent, principally, consist of water, as distinct from solvent based finishes, where no water is present.
Aromatic: Organic chemical compounds with closed ring structure, derived from benzene.
ASTM: American Society for Testing Materials.
Atomizing: The creation of a fine spraymist from a spray gun by compressed air and the sprayhead design.
Automotive Finish: Finish applied to motor cars and trucks. Coatings for motor cars are highly specialised and very demanding in respect of colour matching. A distinction is made between car finishes and car re-spray finishes.
B
Bactericide: A cf. Biocide, specifically used to kill bacteria.
Barrier coating: Other description for cf. sealer, e.g. anti-bleed sealer.
Batch: A quantity of material, manufactured in one operation from raw materials and (or) intermediates and bearing the same batch identifications.
Binder: Film forming component of paints, not containing water or organic solvents.
Biocide: Chemical compound, capable of killing micro organisms.
Bitumen: A dark colour binder obtained as a residue from a distillation of crude mineral oil.
Blast cleaning: cf. Abrasive blast cleaning.
Bleeding: Discolouration of white and pastel paints due to solvent action on binder, dye, or pigment in the base coat or substrate.
Blistering: Formation of blisters in a paint film, usually caused by expansion of trapped moisture or solvents underneath the film by heat.
Blushing: Milky appearance on (clear) Nitro-cellulose lacquers caused by water deposition followed by precipitation. A result of cooling below the dew point by very fast evaporation of solvents in conditions of high relative humidity. Also referred to as blooming.
Bond: 1. cf. Adhesion, 2. Force of attraction between atoms.
Boot topping: Marine paint applied to the section of a ship’s hull between the light and deep load line.
Breathing: Allowing the passage (transmission) of water vapour through a paint film.
Brightness: Total reflectance, sometimes also referred to as lightness. White paints, pigments and extender pigments are being tested for brightness. A high value indicates a pure white color.
Brittle: Paint film condition, where continuous expansion and contraction of substrate results in cracking. Opposite of flexible.
Brushability: Brush application properties of a paint.
Brushmarks: Lines of brush strokes left after brushing in a paint film, due to inadequate flow and levelling properties.
B.S.I.: British Standards Institution.
Buffing: Polishing operation using high speed buffing bands or rubbing compounds.
Build: Dry film thickness obtained in one application.
Burning off: Removal of all layers of paint by means of a blow lamp and a specially shaped scrapper.
C
Caking: 1. Sintering together of powders in bags, 2. Pigment settling in the can to a hard, dry layer.
Can stability: Also called storage stability or shelf life is the period for which a packed paint remains suitable for use under normal storage conditions.
Capillary: Narrow fine bore tube or passage in a substrate.
Catalyst: Chemical substance, which promotes a chemical reaction, without itself taking part in this reaction.
Cathodic protection: Application of a direct current at the anode equal to or exceeding the corrosion current. A system of corrosion protection.
Caustic: Chemical action of cf. alkali, e.g. caustic soda.
Cellulose lacquer: A fast drying lacquer based on Nitro Cellulose, very popular as finish for furniture and spraying of cars.
Cement: White to Grey powder with alkaline reaction. Building material, which after hydration hardens. Use in cement plaster (mixed with cement and water) and concrete (mixed with sand, water and aggregate).
Chalking: Loose pigment formation on the surface on exposed paint films, due to localised loss of binder strength. Incipient film erosion, usually following loss of gloss.
Checking: Film breakdown in the form of (often separate) cracks, which do not penetrate down to substrate. Incipient form of cracking.
Chemical rust removal: Removal of rust by means of (mainly) acidic chemical compounds of pickling.
Chlorinated rubber: Binder extensively used in chemical resistant paint and swimming pool enamels.
Cissing: Partial creeping back and contraction of a wet paint film with the formation of uncovered areas. Also referred to as crawling, this defect is largely due to inadequate wetting.
Clear coating: A coating without pigment or extender pigment. Low gloss clear coatings may contain small amounts of matting agents.
Coagulation: Kick out and precipitation of the binder in a paint, usually caused by overthinning or freezing (aqueous paints).
Coal tar: Liquid by product from the thermal decomposition of coal, mainly used in combination with of epoxy resins.
Coal tar epoxy: Heavy duty industrial coating based on coal tar and epoxy resin and used to protect pipe-lines and chemical plant.
Coating: 1. Surface coating or organic coating modern description for paint. 2. Thin layer of surface active material applied to pigments and to a lesser extent extender pigments.
Cob webbing: Defect on spraying of lacquers based on highly polymerised binders with very volatile solvents. Instead of spraymist threads similar to cob webs are produced.
Cohesion: The power of force by which particles of homogeneous substances are held together, sometimes referred to as internal adhesion.
Cold curing: Curing in the absence of heat, e.g. acid cured floor finish.
Colour: Visual sensation, dependent on the wavelength of light reflected from objects. Light is a composite of various spectrum colours. An object is seen as red if all spectrum colours are being absorbed out only the red portion is reflected.
Colour changes: Variation in colour which can be lighter or darker, caused by chemical attack or sunlight.
Colour matching: Preparation of a colour in paint to match a dry or wet sample. In practice carried out by an experienced operator (colour matcher).
Compatibility: Ability of two materials to blend without any sign of separation of film defect.
Concrete: Building material made of sand, cement, aggregate and water, very often reinforced with a skeleton or mat of steel. Special additives are employed to promote curing and strength of concrete.
Condensation: 1. Chemical reaction in synthetic resin manufacture, characterised by the formation of water. 2. Condensation of water such as in bathrooms and in confined areas on ships.
Consistency: Viscosity of thick materials, e.g. pastes, sealants and compounds.
Copolymer: Polymer manufactured from a mixture of different monomers.
Corrosion: Electrochemical conversion of base metals to their oxides. Corrosion is promoted by high levels of industrial impurities or salt in the air which accounts for the high corrosion rate in coastal and industrial areas. Corrosion can only take place when both water and oxygen are present. The major problem with corrosion is the gradual eating away of the metal with a corresponding reduction in strength. Especially on steel structures this can be fatal if not treated properly and timely.
Covering power: Other description for spreading rate, not to be confused with hiding power or opacity. Covering power is the area covered by a given volume of paint, irrespective of opacity.
Cracking: Film breakdown showing large cracks, penetrating at least one coat. Advanced stage of checking.
Cratering: Formation of small craterlike depressions in a film.
Creosote: Wood preservative based on phenol and phenol derivatives, derived from wood or coal tar.
Cross linking: Three dimensional macromolecular growth.
Curing: Drying, more specifically of non decorative finishes.
Curing agent: Agent, which promotes of curing.
D
Dampness: Wet patches on walls, ceilings or floors due to water ingress.
Damp proofing: Procedures applied to (mainly) walls to cure dampness.
Deck paint: Marine paint used to coat ship’s decks.
Decorative paint: Paint used to decorate houses, flats, schools, etc. as distinct from of industrial paint.
Degreasing: Removal of oil, fat and grease, for which a variety of methods are in use.
Density: Density is the mass per unit volume of a material, nowadays given as kilograms per cubic metre.
Descaling: Removal of mill scale from steel for which a variety of methods are in use.
Detergent: Surfactant with the specific function of penetrating and removing dirt from fibres and surfaces.
Dew point: The temperature at which water vapour reaches saturation point and starts to condense.
Diluent: A non solvent, e.g. hydrocarbons in lacquer thinners.
Diluent ratio: The extent to which true solvents for a specific binder can tolerate diluents without kickout.
Dipping: Application of surface coatings by immersion of objects followed by controlled withdrawal and draining.
Dirt retention: Tendency of paint films to retain dirt, e.g. soot, spume, etc.
Discolouration: Change in color.
Distemper: ]Water based paint, available as dry or cold water distemper and as paste (oil bound distemper). Both types have largely been replaced by P.V.A. and acrylic paints.
Drier: Material added to oil or alkyd based coatings with the object of promoting drying.
Dry film thickness: The thickness of a paint film when dry, expressed in micrometers (previously called microns).
Dry hiding: Hiding power contributed by certain extender pigments or other ingredients in paints, formulated at pigment levels over the cf. critical pigment volume concentration. This type of opacity develops as the paint dries and is mainly utilised in aqueous finishes.
Drying: Film formation, the conversion from liquid paint to a solid layer after having been applied to a substrate.
Drying time: The time taken for a paint to dry to a specific condition.
Dry rot: Specific fungus causing decay of wood with a high water content.
Dry spray: Prematurely dried paint particles in spraymist.
Durability: Exterior life of a coating also referred to as weathering resistance. The period over which paint will give exterior protection without unacceptable film failure. Durability is one of the most important properties of a paint since it will determine repainting cycles.
E
Efflorescence: Crystalline deposit of plaster salts on walls caused by water ingress from outside.
Eggshell: Gloss similar to that of the shell of an egg.
Elasticity: Distensibility (deformation) with complete recovery. The modules of elasticity is the ratio of applied stress to resultant strain. Highly flexible and elastic material have a low modules of elasticity.
Emery: Hard mineral abrasive, extensively used on emery paper and tape.
Emulsion: Dispersion of immiscible liquids.
Enamel: Paint with a very high gloss level and excellent flow properties.
Epoxy resin: Synthetic resin based on epichlorhydrin and bisphenol A (diphenylolpropane). Exhibits a combination of good chemical and mechanical resistance.
Etching: Chemical action of acids on metals.
Etch primer: Also called wash primer. A primer with etching properties. Strictly speaking not a primer, since it only gives temporary corrosion protection, but is mainly used to improve adhesion of subsequent coats of paint. Available in both 1 and 2 pack form.
Evaporation: Change from a liquid state to a vapour without heat application.
F
Fading: Opposite of darkening. colour becoming lighter and paler on exterior exposure or under attack by chemicals.
Fastness of color: Permanence of colour under a variety of conditions, e.g. exposure to light, alkali, line, etc.
Filler coat: Aqueous prime coat with good filling properties used as first coat on walls in water based paint system.
Film: Paint film, the dry layer after a paint has dried.
Film formation: Binder conversion from the liquid state to a dry film. We distinguish between chemical and physical film formation. In the former the binder undergoes a change in chemical composition by oxidation, polymerisation and cross linkage. Physical film formation is purely the evaporation of the solvents in which the binder is dissolved or dispersed.
Film thickness: The thickness of a paint film applied to a substrate. Wet film thickness is as applied, dry film thickness is when dry. Practically in all cases the dry film thickness is less than the corresponding wet film thickness.
Finishing coat: The final coat in a paint system.
Fire retardant coating: A coating specifically formulated and used to prevent flame spread on objects prone to fire, e.g. stage props and thatch roofs.
Fish Eying: Formation of round shiny spots in a paint film.
Flaking: Final stage of film breakdown, where flakes of paint lift away from the substrate. Also called scaling.
Flame cleaning: Metal cleaning process for removal of mill scale and rust by means of an oxyacetylene burner.
Flash point: Temperature at which vapours above a liquid can be ignited by a flame.
Flash rusting: A special type of corrosion in the form of brown rust stains when blast cleaned steel is primed with an aqueous primer.
Flat oil plant: A matt finish, usually based on oils or an oleoresinous varnish, largely replaced by water based products.
Flexibility: Ability of a surface coating to allow ( moderate) expansion and contraction in the substrate without film breakdown. Opposite of brittleness. Not to be confused with elasticity.
Flocculation: Re-aggregation of dispersed primary pigment particles , a notorious paint problem.
Flow: The property of a paint to flow out to a smooth film. Also referred to as levelling properties.
Fluorescence: Property of certain substances to alter invisible light to light within the visible range as long as being exposed to specific radiations.
Foaming: Visible manifestation of entrapped air in paint and varnish during manufacture.
Force drying: Drying of paint films at elevated temperatures of approximately 80-90°C, also referred to as low bake.
Fouling: Marine growth on ship’s bottoms and other underwater structures.
French polish: Alcohol solution of shellac, once popular as finish on furniture. Applied by hand. Nowadays largely replaced by sprayed lacquers and polyesters.
Fungicidal wash: Solution of a fungicide used for washing down fungus infested areas before repainting.
Fungicide: Biocide with specific function of killing fungi.
Fungus: Plant micro organism, reproduced by spores. Mould (mildew), yeast and mushrooms are fungi.
Furniture finish: Coatings mainly used on furniture, e.g. lacquers and polyesters.
G
Galvanised Iron: Zinc coated iron, available in flat sheet, corrugated or I.B.R form. Different thicknesses of zinc metal are produced of which the heavier coating is referred to as the coastal quality. Applied by a hot dip process.
Gel: Colloidal dispersion of a liquid in a solid.
Gloss: Specular reflection as distinct from. Diffused Reflection, an important property of paints, which contributes to aesthetic value.
Gloss retention: The property of a surface coating of maintaining gloss on exterior exposure. Indicative of quality level and normally expressed as a percentage of original gloss.
Glue: Protein derived from animal skins and bones. Contributes to good application and rheological properties of distempers, but nowadays largely replaced by other binders.
Grit blasting: cf Abrasive blast cleaning.
GRP: Abbreviation for Glass Reinforced Polyester, widely used in boat construction.
H
Hammer finish: Industrial effect finish resembling beaten metal. Aluminium pigment based, this finish uses specific solvents and spray viscosities. Popular on flat surfaces, e.g. steel cupboards and control panels. Both air drying and baking types are being used.
Hard dry: Final stage in drying of paint, also referred to as bone dry or through dry. In practice, the stage where painted objects can be handled or packed without damage to the coating (dry to handle).
Hardness: Physical property of a paint film which can be measured by several measuring instruments. Related to toughness and wear resistance.
Heat resistance: Ability of a surface coating to withstand specific temperatures without film breakdown.
Hiding power: Also called opacity or obliterating power is the ability of the paint to obliterate or hide the surface to which it is applied. Depends on type and level of pigmentation and is expressed in square metres per liter.
High build coatin: Coating with a high (dry) film thickness obtainable in one application.
Homopolymer: A polymer derived from one monomer as distinct from cf copolymer.
Humidity: Climatic condition, indicating the presence of moisture in the air.
Hydrophilic: Affinity for and compatibility with water cf Lyophilic.
Hydrophobic: No affinity for and compatibility with water cf Lyophobic.
I
Immersion: Complete submergence, e.g. immersion degreasing.
Impact resistance: Resistance of coating to dynamic impact by a falling weight, expressed by height of fall and mass of weight (cm - kg).
Impurities: Undesirable matter in paints and varnishes, which includes dirt, sand, skins, hard pigment agglomerates, gel particles etc.
Incompatibility: Inability of two materials to blend without any signs of separation or film defect. Materials can appear compatible when mixed but can exhibit film incompatibility.
Industrial finish: Coating specifically used by industry to protect the products of their manufacture e.g. appliance finish, automotive finish.
Inflammable: Easily set on fire, flammable.
Inhibiting Pigment: Rust preventing (anti-corrosive) pigment e.g. red lead.
Inhibitor: Chemical substance added to acid based rust and scale removers in order to prevent attack on bare metal.
Ink: Material used for printing, writing or marking. Although similar in many respects to paints, inks are classified as and manufactured by a separate industry.
Intercoat adhesion: The adhesion of two surface coatings of a paint system to one another.
Interior coating: Coating, exclusively formulated for and used on interior surfaces. Exterior application would result in breakdown.
Interval: Period of time between application of two consecutive coats of paint.
Intumescent coating: A coating, which under heat forms an insulating foam layer, which retards or prevents flame spread to the substrate.
ISO: 1. International Standards Organisation. 2. An isomer of.
K
Kerosine: Illuminating Paraffin.
Knifing filler: Paste filler also referred to as Plamuur (Dutch) of Spachtel (German). Applied by broad knife to fill unevenness in substrates prior to application of the finishing coat.
Knot: Semi circular areas in sawn wood from branches or lumps in tree trunks, invariably a source of rosin exudation.
L
Lacquer: Fast, physically drying surface coating. This type of film formation is also called reversible or non convertible and is entirely based on evaporation of solvents.
Lacquer thinners: Mixture of active solvents, diluents and latent solvents (alcohols) used to dilute nitro cellulose lacquers.
Latex: 1. Natural rubber emulsion. 2. Synthetic resin dispersion.
Leafing: The property of aluminium flakes to move to the top of a wet paint film and align themselves to a continuous bright finish paint (mirror).
Levelling: The property of a paint to flow out to a smooth finish, free from brushmarks.
Light fastness: Resistance to colour change when exposed to light. Property of pigments and paints, incorporating pigments.
Lime: Calcium oxide (quick lime, unslaked lime) and calcium hydroxide (slaked lime) used in certain plasters and lime wash.
Lime wash: Preparation for coating plastered surfaces, prepared form quicklime and water. Oil, rosin, salt and tallow are used as additives to improve water resistance.
Linseed oil: Drying oil, widely used in the paint industry. Prepared from flax seed, available from various parts of the world. Good durability is a feature but pronounced yellowing properties are a draw back. Available as boiled linseed oil and in polymerised form stand oil.
M
Machine cleaning: Cleaning of substrates by mechanical means e.g. needle gun, as distinct from hand cleaning.
Maintenance coating: A paint, mainly used in chemical plant, especially on vessels and tanks.
Marine varnish: Varnish specifically used in a marine environment such as on ships and yachts. Must have good water resistance in addition to exterior durability.
Marproof: The property of a surface coating to withstand marring and scratching without change. Mainly applicable to baking enamels.
Masonry paint: Coating used on exterior walls, also available in textured varieties.
Mastic: Bituminous based sealant.
Matt: Without gloss, also referred to as Flat.
Membrane: Fabric used as reinforcement of (mainly) waterproofing and roof coatings. Membrane made of fibreglass, polypropylene or polyester is sandwiched between coats of paint.
Metal Primer: Anti-corrosive primer, necessary as first coat on metals.
Methylated spirit: Denatured alcohol, unfit for human consumption. Available with a characteristic blue mauve colour.
Micaceous Iron Oxide: Special (extender) pigment, used in structural steelworks paints in which it prevents ingress of moisture. Also referred to as M.I.O
Micron: Unit of length equal to 0.001 mm. Correct name is micrometer.
Migration: The movement of specific substances out of a paint film e.g. plasticizer migration. Direction can be towards the surface or towards the substrate.
Mil: Unit of length equal to 0.001 inch = 25 micron. Also called Thou.
Mildewcide: A biocide, specially used to kill mildew. Since mildew is a fungus, fungicide would be a more appropriate description.
Mild scale: Layer of oxides left on steel by the steel production process. It is generally held that mild scale must be removed prior to painting.
Mineral spirits: Very popular aliphatic hydrocarbon fraction, extensively used in the paint industry. Also called White spirit or Mineral Turpentine.
Miscibility: Ability of liquids to fully mix with each other without signs of separation.
Mist coat: Thin, dry spray coat applied to a substrate prior to application of a full wet coat. A mist coat enhances adhesion and helps in cases of uneven porosity.
Mixer: Machine used for mixing, blending, dissolving and compounding.
Moisture vapour transmission: Movement of moisture in vapour form through a paint film, one of the features of resin is dispersion paints. This property allows to damp substrates without paint failure and is also called ‘breathing’.
Mould growth: Physical evidence of mould growing on walls and ceilings under conditions of high relative humidity, high temperatures, moisture (dampness) and presence of nutrients (e.g. in flour mills).
Mud cracking: Specific type of cracking, which develops in thick paints and fillers, when applied in heavy layers.
N
Nitro Cellulose: Also referred to as cotton or cellulose nitrate. Very popular cellulose ester binder for lacquers. Both ester and alcohol soluble grades are available in a range of viscosity types.
Non-ferrous: Metals and alloys not based on iron, e.g. Aluminium.
Non skid: A coating, which prevents skidding or slipping on smooth, slippery surfaces.
Non Yellowing: The relative resistance of white finishes to change colour to an off white colour on exposure.
O
Odourless paint: Paint without the characteristic paint smell on drying.
Oil: 1. Mineral oil, derived from crude petroleum. 2. Essential oil, obtained from plants. 3. Fatty oils, triglycerides from animals or plants. This category is extensively used in coatings as raw refined and polymerised oil, as well as modifier for alkyd resins.
Opacity: cf Hiding power.
Orange peel: A surface defect of spray applied coatings, resembling the skin of an orange. Caused by spraying at too high a viscosity or using too fast a spraying thinner.
Overspray: Part of the atomised spray coating bypassing the article to be coated.
Oxidation: Chemical reaction with oxygen.
P
Paint: A composite product which when applied in the liquid state to substrates by a variety of methods forms a thin protective and (or) decorative coat thereon. Nowadays referred to as surface coating or organic surface coating.
Paint film: The dry coating left on a substrate after drying of a paint. Composed of pigment, binder and any other solid ingredients used in the paint.
Paint remover: A (mainly) thick substance used to remove old layers of paint. Based on a very strong active blend of solvents, sometimes combined with alkaline materials, surfactants, wax, thickeners and destructive chemicals.
Paint roller: Application tool for paint to large areas, consisting of a hollow core covered with fibre or plastic foam and held in a handle. Both natural fibres e.g. lambs wool and synthetic fibres e.g. acrylics are used in different lengths (nap). Plastic foam rollers are preferred for application of textured finishes.
Penetration: Test method for the determination of the consistency of pastes, sealants, compounds and bitumen. Needles or cones are forced into the material to be tested under controlled conditions and the resulting depth of penetration is measured.
pH value: Hydrogen Ion concentration.
Pickling: Removal of rust and millscale from metals by liquid chemical (acid) treatment. Carried our in pickling baths by immersion.
Pigment: White or coloured powder, which when mechanically incorporated, gives colour and opacity to paints.
Pinholing: Surface defect, mainly in stoving enamels, usually caused by an incorrect solvent balance or inadequate flash off period. The minute holes formed fall to level our and close before the film is cured.
Pink Primer: Woodprimer, which traditionally is being supplied in a pink shade.
Pitch: Dark coloured residue from the distillation of coal tar or fatty acids.
Pitting: Localised cavities in metal caused by corrosion.
Plaster: Mixture of cement, sand and water used as a wall covering on interior and exterior surfaces. Can be modified with lime or plaster of paris to adjust specific properties. Plaster can be smooth (floated), textured (Tyrolean Plaster) or with relief (Spanish Plaster).
Polyester: Synthetic resin based on the reaction of dibasic acids and (mainly) dihydric alcohols.
Polyurethane: Important group of synthetic resins based on the reaction of isocyanates with polyols (NCO and OH Groups). Excel in toughness, adhesion to difficult substrates e.g. GRP and abrasion resistance.
Poly Vinyl Acetate: Very popular type of synthetic resin, mainly used in aqeous dispersion form in PVA paints. Copolymers with acrylics and poly ethylene (EVA) are available. Commercially marketed since 1949.
Pot Life: The period over which a two component coating after mixing will remain suitable for use.
Porosity: Surface condition of a substrate, full of pores, which will cause suction and will affect application properties of paint. Excessive and uneven porosity requires sealers as first coat.
Power tool cleaning: Machine cleaning.
Pre Treatment: Processes applied to (mainly) metal substrates prior to painting e.g. rust and scale removal degreasing.
Primer: First coat applied to a substrate in a normal coat paint system. A primer must contribute lasting adhesion apart from other specific properties, depending on type of substrate (control of corrosion, dry rot, etc.)
Putty: A non-load bearing glazing sealant, originally composed on linseed oil and whiting.
Q
Quality: Level of appearance and (or) performance.
R
Ready mixed paint: Obsolete term to indicate a product, which does not require thinning and is ready for use (RFU).
Red lead: Orange anti corrosive pigment, one of the most effective rust preventing pigments. On account of high relative density red lead had a tendency to settling. Red lead forms lead soaps with most binders, which promote wetting of substrates, improve water resistance and flexibility.
Red oxide: Iron oxide pigment, available in the natural as well as synthetic form. Colours vary from (dirty) yellow undertone reds to deep blue undertone reds. Iron oxide has limited anti corrosive properties. Synthetic types have superior properties e.g. tinting strength, purity and texture.
Resin: A solid or semi-solid, amorphous substance mainly obtained as exudation product from trees (natural resin) of synthetic resin. A distinction is made between Fossil and recent resins.
Retarder: A high boiling solvent added to retard the drying process of physically drying coatings e.g. benzyl alcohol.
Rheology: Science of flow and deformation of materials e.g. viscosity.
Roller application: Application of paint by means of cf Paint rollers.
Roof paint: A coating specifically formulated for and used on roofs, which embrace galvanised iron roofs, asbestos cement roofs, concrete tiles and clay tiles. The two most popular types are based on alkyds and acrylic dispersions.
Rusting: cf Corrosion.
Rust removal: Essential aspect of surface preparation of metal prior to painting. Both removal by hand and by machines are practised.
S
SABS: Abbreviation for South African Bureau Standards.
Sandblasting: Abrasive blast clean, using specific grades of sand as abrasive.
Sanding: Abrading with abrasive paper (sandpaper) or tape (emery tape). Sanding can be done dry or (with water) by hand or machine. Sandpaper is available in a large range of grit sizes from very coarse , very fine to suit all sanding requirements.
Sanding sealer: Nitro cellulose based sealer , mainly used on wood to fill and even out unevenness. Sand before applying further coatings.
Scaling: cf Flaking.
Scrub resistance: Ability of a coating to be scrubbed (under controlled conditions) by a scrubbing brush without film breakdown. Mainly tested on aqueous coatings and must not be confused with washability.
Sealer: 1. Coating applied to porous substrates to eliminate excessive or uneven suction. 2. Coating to insulate a base coat e.g. antibleed sealer. 3. Coating to bind loose or active old coatings e.g. lime wash bonding sealer.
Self cleaning: Exterior painted surfaces which due to a (controlled) degree of chalking, present a more or less permanently clean appearance.
Semi gloss: Degree of gloss, not classified as low gloss. On an arbitrary scale (60° gloss) we can distinguish: 1. Flat (matt) below 10, 2. Eggshell flat 10 - 20, 3. Eggshell gloss 20 - 30, 4. Semi gloss 30 - 50, 5. Gloss 50 - 70, 6. High gloss over 70
Settling: Movement of pigments and (or) extender pigments towards the bottom of paint containers on storage cf caking.
Set to touch: Drying stage of coatings when a light finger movement does not disrupt the film and no tacky feel is apparent.
Shade: Specific detail of a colour in respect of depth e.g. a darker shade of blue or purity e.g. a cleaner shade of red.
Shelf life: Also called storage stability or can stability. The period over which a packed paint remains usable under normal storage conditions.
Shingle: Flat roof tile made from wood, an asphaltic composition, slate or asbestos cement.
Shop primer: A primer applied indoors, prior to despatch and erection.
Shot blasting: cf Abrasive blast cleaning.
Skinning: Premature oxidation of paint in partially full containers, producing a skin on the surface.
Soft wood: Wood varieties, e.g. pine, lighter in colour, softer in texture, more open grained and with a lower content of oily constituents than hard wood.
Solids: The non volatile portion of a paint, consisting of binder, pigment, extender pigment and any other solid ingredients.
Solubility: The ability to form a solution in specific solvents (including water).
Solvent: Volatile, mainly organic liquid capable of dissolving a substance. Water is classified as a solvent in aqueous coatings, even although it does not always dissolve the binder. The function of a solvent is to dissolve, disperse or dilute binders, to control film formation in physically drying paints and to dilute coatings to application viscosity.
Specification: A list of chemical and (or) physical properties sometimes combined with formulation details specified for a particular paint.
Specific gravity: Nowadays correctly called relative density, the mass per unit volume of a material .
Spray gun: Paint application tool for industrial finishes, which atomises a diluted paint and expels same by air pressure onto substrates. Mainly used for fast drying and baking finishes.
Spraying: Paint application process, utilising a spray gun and compressed air. A distinction is made between normal spraying, pressure pot spraying, hot spraying, electrostatic spraying and airless spraying, the latter without the use of compressed air.
Spreading rate: cf Covering power.
Staining: Discolouration of painted surfaces by dissolved salts form e.g. iron, natural dyes from e.g. cedar wood or contaminants of substrates e.g. soot, nicotine, smoke.
Surface area: The total surface area of a given quantity of pigment. Large surface area pigments (e.g. carbon black) exhibit high oil absorption and opacity.
Surface dry: Another description for cf Set To Touch.
Surface preparation: Essential aspect of any painting operation for new work or re-decoration. It includes rust and scale removal, degreasing, removal of loose and perished layers of old paint, filling, sanding and dust removal.
Swelling: Increase in volume of a substance by absorption of a solvent or water e.g. rubber in benzene.
Synthetic enamel: An enamel based on a synthetic material (resin) as binder.
Synthetic resin: A resin prepared from pure chemical substances. If modified with natural substances, the description of semi synthetic resin should be applied (e.g. oil modified alkyd).
T
Tack: The property whereby contact with a (solid) surface results in an immediate resistance to separation.
Tack free: Stage of drying of coatings when a firm pressure with the index finger exhibits no tacky feel.
Tar: Brown to black material obtained by destructive distillation of coal or wood. Used in combination with epoxy resin in chemical resistant finishes.
Test Benzin: Very popular hydrocarbon solvent used in the paint industry. Also called mineral turpentine or turps substitute.
Texture: A raised profile in a paint film, which can be obtained by incorporation of aggregates and (or) fibres or by a highly bodied thixotropic structure.
Thickness: 1. cf Film thickness. 2. common description for viscosity.
Thinner(s): Mixture of solvents to dilute a coating, e.g. lacquer thinners.
Thixotropy: Reversible isothermal sol-gel transformation. Paints exhibiting Thixotropy will reduce viscosity on application of shear and revert back to the original state once shear has ceased.
Through dry: cf Hard dry.
Tinter: Another description for stainer, tinting paste or colorant.
Tinting: Another description for colour matching, the process of preparing specific colours from white tint bases and tinting pastes (colorants). This process can be done manually as well as semi-automatically.
Touch dry: cf Set to touch, also called Surface Dry.
Touch up: Application of paint to small isolated, painted areas to cover blemished or damage.
Transparent: Allowing free passage of light. Transparent finishes do not contain pigments or extender pigments, but can incorporate soluble (coloured) dyes.
Two Pack Finishes: Coating supplied in two separate containers, which must be intermixed just prior to application e.g. epoxy enamels.
U
Ultraviolet Radiation: Electromagnetic radiation lying just outside the visible spectrum and largely responsible for the breakdown of coatings on exposure.
Undercoating: Intermediate coating in a decorative paint system, applied over a primer and underneath a finishing coat. Its main function is to even out undulations in a substrate and to form a firm base for the finishing coat. Very often being sanded to improve these properties.
V
Varnish: Clear (unpigmented) surface coating, producing a transparent finish. The most important varnish type is the oleoresinous varnish with the solid part consisting of a combination of a drying oil and a resin.
Veneer: Thin sheet of wood laminated to cheaper materials such as plywood or blockboard.
Vinyl resin: Group of synthetic resins, all based on vinyl - CH2 = CH , e.g. vinyl acetate, vinyl chloride.
Viscosity: Resistance of deformation of fluids . Also called coefficient of internal friction. A distinction is made between dynamic viscosity (poise) and kinematics viscosity (stoke).
Voids: Open spaces between grinding medium in a ballmill, also called interstices. The volume of voids is of importance in calculating correct mill charge volume.
Volatile: Capable of converting to the vapour phase.
W
Washability: The ease with which various marks can be removed from painted surfaces e.g. dirt, soil, perspiration. Not be confused with of (wet) scrub resistance.
Washprimer: An industrial coating primarily used to ensure good adhesion to specific metals and to give also temporary corrosion protection. Semi transparent hence the ‘washy’ appearance. Also referred to as etch primer and available in both one and two pack versions.
Water absorption: The amount of water required by pigments and extender pigments to reach a specific consistency. The test is usually done with water combined with fixed amounts of specific dispersing and wetting agents.
Waterproofing: The process of rendering a structure waterproof, more specifically application of coatings and membranes to flat roofs.
Water repellent: A coated surface or coating which repels water. Clear silicone water repellents are much favoured for exterior wall surfaces.
Water resistance: Ability of a coating to withstand immersion in water without defects, such as whitening and softening. Marine finishes must exhibit good water resistance.
Weathering: Exposure of paints to the vagaries of the weather resulting in eventual breakdown and loss of protective value.
Wet edge time: The period over which an area of freshly applied paint can be joined without film defects with an adjacent application.
Wet film thickness: The thickness in microns of a paint film, immediately after application.
Wet rot: Specific fungal attack on wood with a high water content.
Wet sanding: Sanding with abrasive paper or cloth, with water or soap solution. Wet sanding gives smoother surfaces and prevents softening of the film.
Whitening: Defect of varnish films with low water resistance. Water is absorbed by the film, which causes swelling, a milky appearance, softening and loss of adhesion.
White rust: White corrosion product of galvanised iron exposed to the weather.
White spirit: Very popular hydrocarbon solvent used in the paint industry. Also called mineral turpentine or turps substitute.
White wash: Another description for cf Lime wash.
Wire brushing: Manual rust removal using a brush with steel wire bristles.
Wood filler: Oil based filler, applied by brush or spraying to fill large open pores in wood.
Wood preservative: Chemical composition to preserve wood from deterioration and attack by insects. Applied at the sawmill by either pressure or vacuum processes.
Working properties: Application properties of sealants, more specifically putty under different climatic conditions.
Wrinkling: Formation of wrinkles in paint films caused by application of heavy coats in direct sunlight.
Y
Yellowing: Gradual darkening of certain binders on drying. In white coatings, this colour change causes whites to take on various shades of broken white, ivory or even cream.
Zinc Chromate: Very popular yellow anti-corrosive pigment used in metal primers.
Zinc dust: Metallic zinc used in one pack and two pack zinc rich primers. These primers confer very high corrosion protection, are very sensitive to moisture and have a high relative density.
Zinc Phosphate: White anti corrosive pigment, gaining in popularity on account of the toxic properties of chromate pigments.