Glossary

GLOSSARY




A     (back to index)
Acrylated Rubber Resin binder produced from the copolymerisation of styrene and acrylic monomers
Acrylic A synthetic resin produced by polymerising various acrylic or acrylate monomers. This resin is used in coatings which have good colour and gloss retention.
Aeration Air bubbles can be formed during stirring, shaking or application of mainly water based paints which can result in a bubbled dry film.
Air Drying Paint Paints which dry by absorption of atmospheric oxygen, the reaction being catalysed by metallic driers e.g. alkyd paints.
Airless Spraying Method of application which uses hydraulic pressure to atomise the paint. Airless spraying is a very fast and efficient method of application.
Alkyd A synthetic resin made by reacting naturally occurring drying oils and other chemicals. Alkyds can be modified to meet varying requirements on speed of drying, adhesion, flexibility, etc.
Anti-Condensation Paint A paint that, under intermittent dry and humid conditions, minimises the effects of condensation of moisture.
Anti-Corrosive Paint A paint formulated to prevent corrosion of steel substrates.
Artificial Weathering The testing of coatings in which ageing is accelerated by exposure to a cycle of ultraviolet radiation and moisture.
B      (back to index)
Base Part of a multi-component paint (Normally 2 component) - e.g. the epoxy component of a 2 pack epoxy-polyamide coating. Base Normally is the larger volume of the two components.
Binder The constituent of the paint which serves to bind together the various constituents as well as securing adhesion to the surface.
Bituminous Paint A paint formulated with coal tar or bitumen as the resin; usually single pack with good moisture resistance.
Bitty Film A film containing traces of foreign particles or “bits”, which project above the surface of the film giving it a rough appearance.
Blast Cleaning Use of abrasive materials such as garnet, steel grit or shot propelled by compressed air to remove mill scale, rust or old paint from steel. This is the most effective form of surface preparation.
Bleeding Discolouration of a new applied coating caused by staining components of previous coatings "bleeding" to the surface. Usually associated with coatings applied over coal tar or bitumen or paints containing inferior organic pigments.
Blistering Localised delamination of a paint film in the form of blisters from the underlying surface.
Blooming The formation of a thin film on top of a glossy paint film thereby reducing the gloss and dulling the colour.
Brushability The ease with which a coating can be uniformly applied to a surface using a paint brush.
C      (back to index)
Chalking The result of photochemical breakdown of the surface layer of binder with consequent release of pigment.
Chipping The removal of paint and surface contaminants from a substrate by means of impact from a manual mechanical sharpened tool.
Chlorinated Rubber A non-convertible binder used to produce single pack paints, with good resistance to acids, alkalies, humidity.
Cissing The partial creeping back or contraction of the wet film into craters which causes small areas of substrate to become visible.
Coal Tar Epoxy A combination of epoxy/curing agent and tar products which give a very water resistant film.
Cobwebbing The formation of fine filaments of partially dried paint during spray application making it unacceptable for this type of application. Normally associated with Chlorinated Rubber paints.
Contrast Ratio The hiding power of a paint film. Expressed as a ratio of coverage over white against coverage when applied over black.
Conventional Paint They are single pack and react usually with atmospheric oxygen when drying and curing. Synthetic resins such as alkyd come into this category.
Corrosion A process by which metal is corroded by chemical or electrochemical influences.
Coverage The spreading rate of a coating.
Crocodiling The formation of wide criss-cross cracks in a paint film similar to a crocodile hide.
Curing Agents Normally the additive component of a two pack coating.
D      (back to index)
Dry Spray A rough, powdery, non-coherent film produced when a spray-applied atomised coating dried before reaching the surface.
E      (back to index)
Emulsion Paints A collection designation for water-based paints where the resins are emulsified, e.g. latex paints consisting of polyvinyl acetate, poly-acrylates etc. In all emulsion paints, the solvent/thinning agent is water and the paints dry as soon as the water evaporates so that the emulsified droplets of resin join together and form a solid film.
Epoxy A resin based on polymerised Bisphenol A containing epoxide groups.
Etch Primer A paint containing an acid which gives an etching effect for use on aluminium and zinc coated steel to improve the adhesion of the subsequent layer of paint. Etch primers must only be applied to bare metals and in very low film thicknesses.
F      (back to index)
Feathering The abrasive smoothing of the firm edge of a film of paint to ensure that patch "repairs" etc. adhere well to the existing coating.
Filiform Corrosion A type of corrosion proceeding under a coat of paint, varnish or related product, in the form of threads, and generally starts from bare edges and local damage in the paint coat.
Filler A product used for filling cracks or voids in a substrate.
Film Thickness The thickness of a continuous layer of paint applied to a substrate.
Flash Point The lowest temperature at which the vapour of a flammable material (solvent) will be ignited by a spark or open flame.
Flotation Separation of one pigment which appears to 'float' to the surface which results in streaks in the surface of the film.
G      (back to index)
Grinning Through The effect observed when a paint has insufficient opacity to obscure the underlying coating or substrate.
H      (back to index)
Hard Settling The accumulation of solids on the bottom of a container of paint which are very difficult to reincorporate.
Hardener A cross-linking agent used to cure a resin or paint system.
High Build Paints Paints which can be applied at high film thickness, normally over 100 microns dry film thickness.
Holidays Defects characterised by an applied paint having areas of insufficient thickness even to the point where parts of the surface may remain uncoated.
I      (back to index)
Intumescent Paint A paint that when heated by a flame swells to form an insulating char. This insulates the substrate from the surrounding heat and provides extra time for evacuation of a building, prior to structural failure of the steel.
J      (back to index)
Jet Fire A fire scenario normally associated with hydrocarbon fuels which has a flame projecting from a small orifice with the fuel under pressure. Very severe fire as there is both temperature and erosive effects of the flames.
K      (back to index)
L      (back to index)
Lacquer A fast-drying clear coating that dries only by the evaporation of solvent.
Latex A suspension of resinous particles in an essentially aqueous medium.
Livering Early stage of gelling that is characterised by the thickening of a paint caused by a chemical reaction between basic pigments and acidic constituents of the binder.
M      (back to index)
Mist Coat A very thin coat of paint usually applied to reduce bubbling of a coating over a porous substrate, sometimes called a sealer coat.
Mixing Ratio The ratio in which components in multi pack paints must be mixed prior to application.
Mudcracking Visible cracking in thick films of paint caused by shrinkage tension during drying, especially observed with zinc silicates.
N      (back to index)
Non-Convertible Describes a paint which dries by solvent evaporation only, e.g. Chlorinated rubber, vinyls etc.
O      (back to index)
Oleo-Resinous Generally refers to resins composed of vegetable drying oils in conjunction with hard resins, which dry by reaction with atmospheric oxygen.
Opacity The ability of a paint film when applied at a given thickness to obliterate the substrate or previous coat from view.
Orange Peel The dimpled appearance of a sprayed film caused by its failure to flow out to a level surface.
Overspray Sprayed paint which misses the surface to be coated.
P      (back to index)
Peeling Loss of adhesion resulting in detachment and curling of the paint film from either previous coatings or the substrate.
Pickling A treatment for the removal of surface contaminants from steel by immersion in an acid solution.
Pigments Powders which give the paint its required anticorrosive or coloured properties.
Pinholes Small holes in through a dry film which form during application and drying of paint.
Polyester Paint A coating using synthetic resin resulting from the condensation polymerisation of various polyacids and polyols.
Polyurethane A synthetic resin containing hydroxide groups cured with an isocyanate hardener (though single pack moisture-cured polyurethanes are available). When an aliphatic isocyanate is used good gloss and colour retention result.
Pot-Life The period of time after the mixing of reactive components of a multi-component paint system, during which the mixed paint can be used without detriment to its application properties or ultimate performance.
Pressure Pot A pressure vessel containing paint and fitted with a compressed air supply to force paint to a spray gun.
Primer Paint intended for protection of metals against corrosion or for preparing a surface for subsequent topcoats.
Q      (back to index)
R      (back to index)
Resin That constituent of the paint which serves to bind together the various constituents as well as securing adhesion to the surface.
Runs Paint film defects in the form of sagging paint in narrow ribbons flowing downwards on vertical surfaces, usually caused by applying the coating above the recommended film thickness or overthinning.
S      (back to index)
Sagging Excessive flow of paint on vertical surfaces causing imperfections with thick lower edges in the paint film, not as excessive as runs.
Saponification A coating defect caused by the reaction of the binder with the substrate or attack of the film by an alkali resulting in a "soapy" film.
Sealer Paint used to seal the substrate or previous coats and prevent interaction between subsequent coats applied.
Sheen Gloss level between 10-30% when measured on an 85° head.
Shop Primer Rust preventing paint, for short term exposure, to be applied to abrasive shot blasted steel. Intended to protect the blast cleaned surface against corrosion during the construction period only.
Silicone Resins Resins based on polymers containing silicon, carbon and hydrogen.
Skinning The formation of a tough, skin-like covering on liquid paints and varnishes when exposed to oxygen.
Solvent-Free Coatings Coatings (normally two components) which contain no solvent.
Spot Priming The priming of small areas of a previously painted surface where the substrate has been exposed.
Spreading Rate The coverage of a material normally expressed as m2/litre
Substrate The surface to which a coat of paint is applied.
T      (back to index)
Textured Paint A coating which by action of application or by incorporation of aggregates has a rough surface to the paint film.
Thinner Any volatile liquid used for reducing the viscosity of coatings; may consist of a simple solvent, a diluent, or a mixture of solvents and diluents.
Thixotropic Paints Paints that have a semi-solid or gel consistency when undisturbed in the tin, but flow readily when stirred or shaken or when under the brush or roller. Thixotropic paints permit the application of thick coats without the risk of sagging.
Tie-Coat A coat of paint applied to a previous coat to improve the adhesion of subsequent coats or to prevent other surface defects e.g. bubbling of a subsequent coating.
Touch-Dry The stage during drying when the coating no longer feels sticky when lightly touched.
Two-Pack Paints based on binders which cure by the chemical reaction between two components.
U      (back to index)
V      (back to index)
Vinyl A synthetic thermoplastic resin used to make single pack paints which dry by solvent evaporation.
Vinyl esters Resins produced from polymerised vinyl monomer where the double bonds are at the ends of molecular chain. These react completely on polymerisation, giving a chemically resistant structure. Because cured vinyl ester resins contain only terminal cross-linking, the entire length of the molecular chain is available to elongate under stress and thus absorb mechanical or thermal shocks. The end result is a tough chemical resistant material especially when pigmented with glass flake.
Volume Solids Percentage of the total volume of the paint made up of non-volatiles.
W      (back to index)
Wash Primer A paint containing phosphoric acid which gives an etching effect for use on aluminium and galvanized steel to improve the adhesion of the subsequent layer of paint.
Water Spotting The spotting or bleaching effect caused by the interaction of water with the paint film surface during drying.
X      (back to index)
Y      (back to index)
Z      (back to index)
Zinc Phosphate A phosphate pigment with corrosion inhibiting properties.
Zinc-Rich Paints Paints containing large proportions of metallic zinc in the dry film, giving extremely efficient anticorrosive properties due to the cathodic protection effect of the zinc.
Zinc Silicate Paint Zinc paints based on either a water soluble or solvent based silicate binder giving very good protection against corrosion.

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