Acrylic

A type of resin used in solvent borne and waterborne industrial and decorative coatings and inks. Often reacted with other resin types to achieve the right properties.

Additive

A liquid or powder added in small, carefully controlled quantities to a coating, usually in production, which makes important, changes to the performance of the coating in application and/or performance. Their uses include keeping heavy pigments for settling, speeding up drying, preventing skinning in the can, adjusting electrical conductivity for spraying, helping film flow, making the surface of the film more or less slippery, slowing down weathering and reducing smell.

Adhesion

With the exception of strippable coatings used for the temporary protection of polished metal, coatings must have good adhesion, sticking to the substrate despite knocks and atmospheric attack. Adhesion on a porous substrate such as paper may require the binder to be partly carried into the substrate to seal it. Substrates should be thoroughly clean for maximum adhesion, and may need a degree of surface roughness to be provided, as, for example, when domestic gloss paint is rubbed down with abrasive paper or steel is shot blasted before coating.

Air Drying

A coating system, which dries at normal temperatures. Some dry just by the evaporation of solvents, whilst others also cure by reaction with the oxygen in the air.

Alkyd

A type of resin used particularly in decorative gloss paints some (generally lower performance) industrial coatings and inks. It may air dry or to be staved to cure. It is generally solvent borne, but can be used in water born systems.

Anilox

A roller with a fine, even patterning used to pick up and meter ink onto a flexographic printing plate.

Application

The ease with which a coating can be applied to the substrate by the customers' processes.

Attritor

 A piece of dispersion equipment which can quickly disperse some liquid coatings in a single operation. Filled with small ceramic or steel beads, the coating is loaded and ground in the beads by a rotating impeller. The heat generated is removed by a water jacket.

Bead Mill

A piece of secondary dispersion equipment for liquid coatings in which the coating, pre-dispersed on a high speed mixer, is pumped through a tube packed with beads rotated by a central agitator. The tube may have its axis vertical or horizontal, and is cooled by water to keep the temperature controlled. More viscous products can be processed in similar 'rod mills' in which the beads are replaced by a number of steel rods lying parallel to the axis of rotation of the main shaft.

Binder

A binder is generally a "resin", a high molecular weight hydrocarbon which forms the integral film of a coating by curing. Resins may be thermoplastic (PVC), which means that they can be cycled through solidifying/softening without significant chemical change; or they may be thermosetting (e.g. epoxy) resins which change their chemical structure on curing to a solid film which cannot be re-melted. A few binders are wholly or partly inorganic, such as cement or ethyl zinc silicate.

Blade Mixer

A primary dispersion machine for viscous coatings and pastes. Litho inks, putties and fillers are commonly processed. One or more blades - often of a 'Z' shape, rotate and knead the paste. Dissipating heat is difficult, so the process can be slow.

British Coatings Federation (BCF)

The British Coatings Federation is the trade association for the paint and ink industry of the United Kingdom. BCF promotes the interest of the industry, and provides and interface between companies, government, other organisations and the general public.

Carbon Black

The most intense black pigment, virtually pure carbon, made from the incomplete combustion of petrochemical oils of gases.

CEPE

The pan-European trade association of the coatings industry, the Confederation European des Associations de Fabricants de Pientures, d'Encres d'Impriemerie et de Couleurs d'Art includes as sits members the national trade associations and, as Corporate Associate Members, many of the major pan-European coatings producers. It promotes the interests of the industry, particularly with the Community and other international organisations. Health, safety and environmental issues are of particular concern.

Charcoal

A black, porous material left over when wood or bones are burned without a full air supply. Consists almost entirely of carbon.

Chemical Resistance

Some coatings have to be used in interior or exterior situations in which they have a resist chemical attack on themselves and protect the substrate from attack. Epoxy resins are frequently used as the binder for such coatings. An associated problem is stain resistance, particularly important in white goods and other equipment to be exposed to curries and pickles.

Cladding

Coated profiled sheets of steel or aluminium used for walls or roofs of buildings.

Classifying

A process of grading particles of power according to particle size. Sieves or air vortexes may be used, particularly to remove 'fines' that may cause problems in application equipment.

Clearcoat

The top, clear, coat of a car paints system. Used in vehicle refinishing, as well as for original painting of cars.

Coating System

Two or more layers of coatings, generally different coatings serving different purposes: for example, suitable pre-treatment followed by a primer to provide adhesion and corrosion resistance, then an undercoat to obliterate and bring the colour closer to the final shade required, and a topcoat to provide the aesthetic appearance over the life of the coating.

Coil Coating

Painting (and/or laminating with sheet plastic) metal in coil from before forming the metal into cladding or finished components. Also known as refinishing.

Construction 

The construction market is made up of users who coat new articles and components for use by the construction industry. Metal and wood are the main materials that are coated. Articles produced include cladding for walls and roofs (often coil coated), windows and joinery. Most coatings are spray applied or coil coated. Curing is generally by stoving for smaller items, and by air drying for larger items.

Correct Colour

On some coatings systems, such as primers and undercoats, high levels of colour accuracy are not important. In most topcoats and inks, however, accurate colour is vital, and the aim is always to keep consistency of colour between batches, as well as matching the standard. On each batch, therefore, the aim is to set the colour between the last batch and the standard. Colours may be compared by eye using various standard illuminations in a light cabinet. More usually they are also compared using colour computers, which can not only measure the closeness of the match, but can calculate the amounts of stainers required to improve the match to the standard colour. A key problem in matching colours is to make sure that the match is acceptable, not just in daylight but also in, say artificial light. Colours that match in one light but do not match in other lights are said to show metamerism.

Corrosion

The process of oxidisation of a metal, generally, for paint makers, steel or aluminium. Seen on iron or steel as rusting, it may be accelerated by moisture or chemical in the air. It has been estimated that the annual cost of corrosion in the UK alone is about £3 bn. A year.

Corrosion Resistance

The ability of a coating system to slow corrosion, often achieved by the inclusion of pigments based on metallic zinc or compounds of zinc, lead or calcium. Good adhesion and water resistance of the coating is generally also important, to prevent access of moisture to the metal substrate. Other systems offer corrosion resistance such as coating with zinc (galvanising), and may be used on their own or in conjunction with a coating system.

Cross-link

The process by which polymers become interlinked to form a solid, three-dimensional matrix. Chemical bonds are formed between neighbouring molecules of the polymer(s) present, by allowing them into contact by evaporation of solvent; or by heating; or by chemical reaction using a cross-linking agent.

Curing

Converting the wet or powder applied coating to a dry, continuous film by the application of heat, a reactive chemical, some form of radiation or atmospheric action.

Curtain Coating

A method of applying a liquid industrial coating by passing a substrate (which is usually flat) at a steady speed under a 'curtain' of the coating.

Cyclone

A Machine into which powder coatings are blown during manufacture, which uses an air vortex to separate oversized particles (which drop through the centre), undersized powder dust (which is blown out of the current of air) and powder of the correct particle size, which is collected for packing.

Decorative

The decorative paint market in the UK buys more than 300 million litres of paint each year, valued at over £500 million. European users consumer almost 2.5 billion litres per year. Products are designed for either interior or exterior use, although "exterior use" products can be used in interior applications. Products specifically for interior use include emulsion paints for walls and ceilings and a variety of special paints for specific applications such as in kitchens or bathrooms. Products for exterior use include gloss and masonry paint, and a wide range of varnishes and stains for wood care. The market is made up of DIY and Trade users.

Diluent

A liquid part of wet paint which does not contribute as a solvent to dissolving the resin, but nevertheless reduces the viscosity of the paint to help with application.

Dilute

To make something less strong, thick or concentrated.

Dipping

A method of coating in which the article is immersed in the coating and withdrawn at a steady rate, drawing with it a uniform coating of film.

Dispersion

The process of separating pigment agglomerations into smaller particles and mixing them into the binder.

Distile

A process for separating a mixture of liquids, during which the liquid mixture of substances is boiled, and the vapour escaping is condensed and collected. The early material collected will be the lowest boiling point component of the original mixture, whilst later materials will be of a higher boiling point.

Distributor

A business, which may or may not be owned by the coatings manufacturer, which distributes coatings and other materials, used by its target industry. They are particularly important in distributing vehicle refinish and yacht paints, and is important for marine paints, litho and screen inks. Trade paints distributed through a variety of shops and stores.

Dry Dock

A dock with closing doors into which large ships can sail and from which the water can be pumped or drained out. Essential for substantial engineering works below the water line, in particular for painting with anti-fouling paint.

Electrical Conductivity

A measure of the paint's ability to take up an electric charge, important in electrostatic spraying.

Electro coat

A type of waterborne primer for metal surfaces which is applied by immersing the substrate in the paint and applying an electric charge to it. Used primarily in the automotive industries.

Electrophoretic Coating

The process of applying electrocoat.

Electrostatic

Describes a process in which something acquires an electrical charge and is as a result attracted to an article of opposite charge, or replaced by an object with the same charge. In coatings industries this property is usually used in the application of both powder and wet paints, and in ink jet printing. The coatings particles are electrically charged as they leave the gun/jet head and are attracted to the earthen substrate. As the coating thickness builds up on the substrate, its attractiveness to the coatings particles diminishes and, especially with powder a fairly even film thickness can be achieved.

Emulsion

A stable mixture of two liquids, which will not dissolve in one another. In making emulsion paint, water and various solvents, which mix with water are the 'continuous phase' which holds tiny droplets of liquid resin polymer dispersed.

Engineering

The engineering market is made up of users who coat articles and components fabricated out of metal. Powder coatings are frequently used, as well as wet paint. Some primers are applied by dipping, but most coatings are sprays applied.

Environmental Science

Scientific study of environmental issues. It is important to achieve objectivity and the best possible solution to environmental science is a developing branch of science, which studies the environmental impacts of products, processes and their alternatives. It includes life cycle analysis, which examines the environmental impact of products from their cradle to the grave.

Epoxy

A family of resins of many types, usually with very good adhesion and chemical protection, but only moderate resistance to light.

Evaporation

Occurs when part of the liquid in a coating becomes a vapour (either at normal temperatures or with heating) and disperses, generally in the atmosphere.

Film

The process of removing solid and semi-solid impurities from a liquid coating by use of paper or cloth filters. One of the important jobs of a paint maker is to prevent the impurities getting there in the first place.

Finishing Tanks

Mixing tanks with a relatively slow agitation in which liquid coatings.

Flexibility

Most substrates move - paper and plastics demand that inks be particularly flexible - but even wood, steel and concrete move with temperature changes or when the surface is knocked. Brittle coatings which fly off at times like this would be useless. Some resins are naturally more flexible than others and may be used in blends to give the coating flexibility. Additives called plasticisers are also often used. Care, however, is need to balance out the amount of flexibility in the formulation with other properties of the coating such as hardness and ease of cleaning.

Flexographic (Flexo)

Flexo printing is a form of relief printing which uses a flexible plate. Firstly ink is transferred from the ink bath to the printing plate via the anilox roller. The substrate, which is usually plastic film or carton board for the printing industry, is fed from a reel through the machine in a continuous web.

Furniture

The furniture market is made up users who coat wooden furniture using clear or pigmented coatings. Coatings may be applied by roller, spray or curtain, and are cured by air drying, heat or UV.

Gloss

The proportion of light reflected from a beam of light falling at an angle on the surface. Gloss may be reduced by increasing pigmentation, changing the types of pigment used (for example, by the use of matting agents), or by chemical additives.

Gravure

The image area is etched or engraved into the metal surface of a printing cylinder. These etched "ducts" are filled with ink as the cylinder rotates. Excess ink is removed from the non-image area with a doctor blade. Ink is transferred to the substrate by the pressure between the printing cylinder and the impression roller.

GRP

GRP is defined as Glass Reinforced Plastic - a plastic that has been reinforced by the addition of glass fibres. This makes the plastic strong, light weight and more durable than a standard plastic. GRP’s bulk strength and weight properties are also very favourable when compared to traditional metal alternatives. GRP can be easily moulded and is used for the construction of anti-slip sheeting, roofs, cladding, boats plus more. 

Hardness

Coatings should not scratch or mark easily. The most extreme example is paints for the bows of icebreakers, which use extremely hard pigments to enable them to stand up to months of cutting through pack ice. Another form of marking can occur when coatings rub together, particularly in printing and packaging applications. Rub resistance may be improved by using small amounts of waxes as additives.

Health & Safety Data Sheets

A document providing storage and handling instructions for raw materials and finished trade and industrial coatings, and inks. Particular hazards, if any will be described in detail, together with first aid instructions.

Heat Set

A litho printing process using reels of paper ('webs'), in which the ink is cured quickly before the web is rewound by infra red heat.

High Solids

Coatings in which the solid or potentially solid parts (mainly resins and pigments) from a large part (usually over 75%) of the coating's volume.

High Speed Disperser

A powerful mixer for liquid coatings, which can be used for primary or complete dispersion, depending on the coating involved. A vertical shaft with a blade (which may be in a specially designed cage) can be lowered into the mixture of resins, thinners and pigments. Rotating at high speed, the blade, if positioned at the right height, can create a severe vortex, circulating the coating and dispersing the pigments.

High Viscosity Mixer

A general term for pug mixers, blade mixers and vertical mixers which can disperse pastes and heavy slurries.

Independent Distributor

A distributor, generally of trade paint, who is not owned by a coatings manufacturer.

Industrial

The industrial paint market in the UK buys nearly 300 million litres of paint each year, valued at over £700 million. European users consume over 1.6 billion litres each year. Products are often designed for users' specific applications, tailored specifically for the method of application and curing to be used, as well as for the end use of the cured coating. The market is very diverse, but further details of groups of users can be found under Protective coatings, Marine, Transport, Engineering, Construction, Furniture, Plastics, Electronics and Packaging.

Ink Jet Printing

Ink jet printing is a non-impact process - no pressure is applied to the substrate. A jet ink is fired from a "gun"! and is broken up into a stream of minute droplets of ink. These are all electronically charged to a predetermined level before passing between deflector plates which alter their individual flight paths to the substrate, and so forming the required image. Because it is non-impact, this process can print on almost any surface.

Inks

The ink market in the UK buys more than 120,000 tonnes of ink each year, valued at over £350 million. Major users include the Publishing and Packaging industries. There is a wide range of smaller users supplied by general and specialist printers, such as the commercial and promotion markets.

Inorganic

Not chemically based on or derived from hydrocarbons.

Intercoat

The ability of one coat to stick to a.other

Kettle

Coatings industry dialect for a reactor, particularly of the type used to make alkyd resins.

Kibbling

Breaking sheets of cooled powder (or any other resin) into flakes.

Letterpress

The oldest and simplest of all the printing processes. It is a "relief process", with the image area standing out of the printing plate. Paper is then placed directly onto the inked relief surface, and by applying pressure the ink on the plate transfers from the image to the substrate.

Linseed Oil

Oil from the seed of the flax plant historically used after heat treating as a medium for varnish and coatings.

Litho

Litho printing is a planographic process. This means that the image area and the non-image area both lie on the surface on the surface of the printing plate in the same place. It works on the principle that oil and water won't mix. The printing plate is treated to produce ink-receptive areas for the image and water-receptive areas for the non-image. The plate is first wet with water, then immediately by ink, creating the desired image in the ink-receptive area.

Long Oil

An alkyd resin containg more than 60% of a vegetable oil (linseed oil, soya oil etc...)

Marine

The marine paint market is made up of users who apply paint above and below the waterline of ships and boats exteriors and also to the interior. The market can be split into three sectors, based on the size of the vessel being painted. At the top of the scale are the large passenger, cargo or naval vessels which are often international in their movements and need to be dry docked, often anywhere in the world, for major painting. In the middle are smaller boats, such as fishing boats, which can be hauled out of the water on a slipway. At the bottom of the scale are leisure craft, maintained by their owners or by specialist shipyards. Costing are applied by spray, roller and brush.

Markets

Groups of coatings users with similar needs. The groups may be subdivided into several levels of 'segments'. Key coatings markets are decorative (subdivided into DIY and trade), industrial (protective coatings, marine, automotive, heavy transport, agricultural construction and earthmoving equipment, vehicle refinishing, construction, general engineering, furniture, plastics and packaging) and inks, where markets tend to be defined by the type of printing process (flexo, gravure, sheet fed litho, cold set web offset, heat set web offset).

Material Safety Data Sheets

A document providing safety, storage and handling instructions for raw materials and finished coatings. Particular hazards, if any will be described in detail, together with first aid instructions.

Metal Oxide

Pigments used by early paint makers, made by grinding naturally occurring minerals or ores. Iron oxides were particularly important, either as relatively pure red oxide or as ochre, a mixture of iron oxide in clay. Siennas and umbers are naturally occurring mixtures of iron and manganese oxides.

Metameric

Colour effect caused by matching colours using different pigments, hence a colour change occurs under diffrent light sources.

Micron

Metric measurement equating to one thousandth of a millimetre. (25 microns = 1 mil)

Mil

Imperial measurement equating to one thousandth of an inch. (1 mil = 25 microns)

Millbase

Initial pigmented coatings dispersion (resin, solvent, pigment and additives) after primary milling and prior to secondary dispersion or thinning.

Millscale

Layer of Iron Oxide on steel surfaces that should be removed before coating.

Mixers

Machines for mixing coatings, generally at low speed to make liquid mixes or tinting/thinning. Also called stirrers.

Moisture Curing

A coating system, based on isocyanates, which cures on exposure to water or water vapour in the air to form a polyurethane.

Molecule

A grouping of atoms, bonded together to form the smallest unit of matter into which a particular chemical substance can be divided without losing its unique chemical identity. Many organic molecules such as resins occur in long, complex chains and/or rings, with carbon atoms providing much of the skeleton of the molecule.

Munsell Colours

Colour system introduced by Albert Munsell (1905).

Natural Colour System

Colour system introduced by the Scandanavian Colour Institute (1979).

Needle Gun

Hand held gun, comprising of a series of needles, which are operated by compressed air and used in steel preparation.

Nitrocellulose

Made by reacting cellulose (from wood pulp or cotton) with nitric and sulphuric acids, it is a highly inflammable resin if allowed to dry. For this reason it is always kept dampened with solvent or water. It is generally mixed with other resins and plasticisers (to give the film flexibility).

Non Convertible Coating

Coating that is soluble in it's original solvent blend.

Non Drying Oil

Oil that will not dry when exposed to air.

Non Ferrous

Metals that contain no iron.

Non Volatile

Remainder of the coating once the solvent (volatile) has evaporated.

Oil Absorption

Measure of the oil absorbed by pigments.

Oil Length

Proprtion of oil to resin in a binder.

Opacity

The ability of a coating to hide or obliterate the substrate. Film thickness increases opacity, but performance and economics may demand high opacity at relatively low film thickness', such as in litho or gravure inks. Pigments are key to opacity, with different pigments offering different degrees of opacity, by virtue of their different light refracting (bending of light beams as they pass into or out of pigment particles) or light absorbing powers, but different media will also have some effect.

Orange Peel

Surface effect that creates an appearance and texture like an orange peel.

Organic

Chemically based on or derived from hydrocarbons.

Osmosis

The transfer of liquids (water) through a coating or substrate.

Overspray

Wasted coating which goes beyond the area being painted.

Oxidation

The presence of oxygen that reacts with alkyds to help the drying process; or react with substrate to create oxide layers.

Packaging

The packaging market is made up of users who manufacture packaging out of metal, plastic or paper, and coat their packaging for decorating, information and protection. Major coatings users include can and drum makers, carton makers and plastic packaging specialists. Coatings used include paints, inks and varnishes.

Phosphating

Metal treatment comprimising of a solution of metal phosphates and phosphoric acid to form a coating which inhibits corrosion and improves the adhesion of subsequent coatings.

Pigment

A fine dry powder which, when mixed with a binder, gives a coating colour (including black or white). They are generally opaque and give opacity to the coating, and may also give other properties such as corrosion resistance.

Pigment / Binder Ratio

The ratio of Pigment to Binder.

Pigment Volume Concentration

The concentration by volume of pigment in a coating or dried film.

Pine Resin

The sticky exudation from pine trees.

Pitch

A sticky dark substance, originally the residue from distilling turpentine from pine roots. Modern pitch is the residue from the boiling of tar.

Plastics

The plastics market is made up of users who coat plastic components and furniture using clear or pigmented coatings. Coatings are generally applied by spray and cured by air drying, moderate heat or UV.

Polyester

A resin with a mix of properties which make it attractive as a general purpose industrial coating for powder, coil coating, general metal finishing and wood finishing. It has good exterior durability but lower chemical resistance than epoxy.

Polymerise

The process of forming a polymer from monomers of simpler polymers. The process may form chains, with or without branches, rings, nets or honeycomb structures.

Polyurethane

A widely used resin with good properties of adhesion, flexibility, hardness and weathering. They may be two component, moisture curing or single component resins used in stoving applications.

Polyvinyl Acetate

A polymer commonly used in emulsion paints & adhesives, also known as PVA.

Polyvinyl Chloride

PVC, a polymer used in coil coatings giving high flexibility and, in thick films, very good durability.

Potlife

Time interval, after mixing, that a coating remains usable.

Powder Coating

A coating made of finely ground particles of solid paint which are generally sprayed electrostatically to cover the article being coated. The powder coated article is then stoved, when the powder melts, flows out to form a continuous paint film before reacting chemically to become a solid inert coating.

Pre-finishing

Coating (and/or laminating with sheet plastic) metal in sheet, strip or coil form before forming the metal into cladding or finished components. Also known a coil coating when using continuous coil as the substrate.

Pre-Mixer

A process of mixing liquid, paste or powder coating components to prepare them for dispersion.

Pre-treatment

A process prior to painting in which the steel or aluminium substrate is cleaned and treated with a solution (usually) of corrosion inhibiting chemicals such as acid phosphates or chromate's. Can also be used to describe flame or electrical treatment of plastic prior to coating.

Primer

A coating which ensures adhesion between the substrate and the remainder of the coating system. Often used on metals, where it may be formulated to give improved corrosion protection, and on wood, prior to the application of pigmented coatings.

Protective Coatings

The protective coatings market is made up of users who apply protective and anti-corrosive coatings, usually to steel and concrete structures. Most users are highly specialist painting contractors working on structures where the standard of protection required is very high and access is often difficult. These include bridges, heavy industrial plants, offshore drilling rigs and production platforms. Coatings are applied by spray whenever possible, and by roller or brush when it is not.

Publishing

The publishing market is made up of publishers and specialist printers who produce newspapers, magazines, books and literature of all sorts. Coatings used are mainly inks, which may be applied by web off-set letterpress, flexographic or gravure processes. Curing is either by air drying or heat set.

Pug Mixer

A mixer for high viscosity pastes, usually a U-shaped steel trough, over which are two horizontal shafts carrying blades. The shafts counter-rotate, and can disperse very high viscosity pastes.

Rain Spotting

Marks caused by exposure to rain soon after application

Reactor

An enclosed vessel in which resin are produced. Also known as a kettle

Re-coat Time

The time interval between each application of a coating.

Resin

A high molecular weight hydrocarbon which forms the integral film of a coating by curing. Resins may be thermoplastic (PVC), which means that they can be cycled through solidifying/softening without significant chemical changes; or they may be thermosetting (e.g. epoxy) resins which change their chemical structure on curing to a sold film which cannot be re-melted. Also known as binder or medium.

Resin Plant

A factory or factory area in which resins are manufactured.

Salt Spray

Accelerated Weathering test to assess corrosion resistance by exposing item to a fine, salt solution mist.

Sand Blasting

Method of preparing steelwork by shooting aabrasives (sand / grit) at very high pressure onto the surface.

Sand Mill

A form of vertical bead mill, in which the coating, pre-dispersed on a high speed mixer, is pumped through a tube packed with beads rotated by a central agitator. The tuber is cooled by water to keep the temperature controlled.

Saponification

Formation of a soap-like substance caused by chemical attack of an alkyd caused by alkali and moisture in a substrate.

Screen Printing

A printing process in which the ink or varnish is forced by a squeegee through fine holes in a flat or cylindrical mesh to form the image to be printed.

Settling

Layer or residue of material at the bottom of a coating.

Shelf Life

Maximum period of time that a material may be stored and remain in a usable condition.

Sieving

The process of removing sold and semi-sold impurities from a liquid coating by use of a sieve.

Single Roll Mill

A form of dispersing equipment, little used now, in which the coating was fed around a rotating steel roller and into a tight 'nip' formed by a steel bar held against the roller.

Sinkage

Loss of gloss level due to the coating being absorbed into the underlying coating or material.

Skinning

A potential fault for air drying paints and inks if their top surface dries in the can or when exposed during normal use. Anti-skinning additives are used to control this, and Litho ink manufacturers may float an anti-skinning solution on the surface of the filled ink pot, or evacuate the air in the space above the ink prior to lidding.

Sleepiness

A loss or lack of gloss as a coating dries.

Solar Reflecting

Coating used to reduce the absorption of heat onto a surface.

Solvent

Although water is sometimes a solvent for certain resins, usually refers to an organic liquid in which resins may be dissolved and which evaporates readily to the atmosphere leaving behind a film or coating.

Solvent Based

A coating system in which the resins are dissolved in non-aqueous solvents.

Solventless

Coating that is free of all solvents.

Soya Oil

The oil extracted from the soya bean, it is less yellow than linseed and forms an important constituent of alkyd resins.

Spot Colour

The litho process often uses a 'process set' of four inks, for which most colours can be mixed on the paper by using the amounts of ink determined by the colour separation made for each of the four plates involved. Whilst this works very well for pictorial work, designs which use solid colours are better reproduced using a special plate and ink - a spot colour - for that colour.

Spraying

The process of coating a surface by breaking up a coating into small particles (in the case of a liquid coating, by forcing it through a fine nozzle) which are then directed, possibly with the help of a current of air or an electrostatic charge, onto the surface.

Squeegee

The flexible blade used to force the ink through a screen in screen printing.

Stay Fresh Ink

Ink formulated so that it will not cross-link if left open for a few hours (overnight, for example) on a litho press.

Stove

To use heat, particularly in hot air ovens, to cure coatings.

Substrate

The surface onto which a coating system is placed, and to which it adheres.

Surface Tension

Cohesive strength of a coating.

Syneresis

Oil / Resin visble on coating surface due to pigment settlement in container.

Tall Oil

Obtained as a by-product of making wood pulp, this is an important ingredient of alkyd resins.

Thermoplastic

Material which become soft / fluid on contact with heat.

Thinners

A liquid which dilutes a liquid coating system, making it easier to apply, and sometimes aiding adhesion by carrying the binder into the substrate.

Titanium Dioxide

Also called by its chemical name Ti02, this pigment has been the key to moving away from the old creamy or greyish whites (still to be seen in, and still faithfully made by paint manufacturers for, stately homes). Its performance is due to its extremely high refractive index, which means that once light gets into a crystal of Ti02 it has great difficulty, getting out again, giving a coating of high opacity as well as being bright and white. Chemically it is very stable, it weathers well and does not stain.

Topcoat

The final, top, coat in a coating system, providing the long term aesthetic appearance of the coating.

Tote Bins

Containers of metal (sometimes with plastic tanks) which are handled by forklift trucks. They generally hold 1,0000 litres, but various sizes are available down to about 200 litres. They are normally reusable.

Triple Roll Mill

A piece of dispersion equipment for dispersing medium to high viscosity pastes very finely: the film of paste is spread out very thinly so that pigment particles are crushed in two nips formed between three rollers, which rotate at different speeds and in different directions. The coating may be packed (or "potted") straight from the apron of the triple roll mill.

Turpentine

The earliest solvent, it was made by distilling parts of pine trees, particularly the semi-liquid resinous exudation.

Two Pack

A coatings system in which two components of the system are manufactured and supplied separately. On mixing the two components prior to application, a chemical reaction occurs over a period of time (the 'pot life') which may be measured in hours or seconds. This reaction (which may be accelerated by stoving) results in the coating forming a continuous dry film.

Ultra Violet

An electromagnetic radiation, similar to visible light but of shorter wavelength, which is emitted from the sun and from specially designed lamps. It often has an effect on resins, in some cases causing them (with the help of other chemicals called photoinitiators) to polymerise. In other cases natural UV can cause the breakdown over time of the resin in the cured film. The polymerising property is used in UV curing systems, while additives (UV absorbers) check the destructive properties of natural UV.

Ultrafiltration

A process utilising membrane technology to recover usable paint from certain paint wastes, such as surplus spray ("overspray") from wet paint spraying and excess coating ("Cream coat") from Electro-deposition. These wastes are collected in water. Ultra-filtration concentrates the wash water back to the original application constants of the coating. Not only does this system save paint, the water can be re-used and it reduces the waste which has otherwise to be treated and sent to landfill.

Undercoat

An intermediate part of a coating system, generally applied over primer or previously painted surfaces, which has high obliterating power and ability to provide a more level surface for the topcoat. In protective coating and industrial applications it is often called a 'build coat'.

Varnish

A mixture of binder and thinner in a clear or coloured liquid which forms a transparent film on drying.

Vehicle Refinish Paint

Coatings applied to a vehicle after its construction and initial painting: may be applied in car plants to repair damage, but is more usually applied in body shops to repair damage or change appearance.

Viscosity

The ability of a liquid coating to resist forces causing them to flow. Water has a relatively low viscosity, whilst some resins such as pitch are very viscous. Viscous coatings will resist forces such as brushes or rollers used to apply them. Viscosity usually reduces as temperature rises, so some coatings (such as powder coatings) only become liquids as high temperatures. If the viscosity is too low, however, the coating may not stay on the substrate at the correct thickness and evenness, so a balance is required.

VOC

Volatile organic compounds are any organic liquid and/or solid that evaporates spontaneously at the prevailing temperature and pressure of the atmosphere with which it is in contact. VOCs can contribute to poor air quality by raising ozone concentrations at ground level in certain climatic conditions.

Volatile Content

Percentage of coating that evaporates.

Water Based

A coating which is carried in water as the main liquid component. The coating resin may be dissolved in the water (although this is unusual), or it may be emulsified, or it may be dispersed in small particles.

Water Resistance

Coatings films absorb and transmit water and water vapour. Sometimes this property is used positively as, for example, in emulsion paints which allow new plaster to dry out through them, or microporous wood coatings which allow the wood to "breathe". Generally when formulating exterior coatings, the aim is to maximise the water resistance of the film.

Weathering Resistance

Coatings systems are broken down over time by the action of UV light, atmospheric moisture and acidity, and accelerated by infra-red radiation. For coatings to be used outside, it is important to slow the break down of the coating as much as possible. The is done by a combination of weathering-resistant binders and pigments, the use of special additives such as UV absorbers and the design of the coatings system itself, including its thickness.

Weatherometer

A laboratory machine which replicates changes in lighting and atmospheric conditions, providing a greatly accelerated guide to the likely weathering performance of a coating.

Web Offset

A litho printing process, printing paper in a reel rather than sheet by sheet. Inks may dry by absorption into the paper, followed by oxidation ('cold set'), or by curing in ovens ('heat set'). Cold set is used primarily for newspapers, because newsprint offers rapid absorption of part of the inf. Glossier papers used for magazines, tourist brochures and catalogues are not so absorbent, and the heat set process gives a high quality of reproduction at high running speeds.

Wet Edge

The extremity of the coating which remains workable, particularly on a large surface.

Wet Edge Time

The time that a coating remains workable, allowing freshly applied coating to join up without showing.

Wet Film Thickness

Thickness of coating immediately after application.

Wet on Wet

Coating applied directly onto coating which has not dried.

Wetting

The coating of pigment particles with thinner (not necessarily water) and resin.

White Spirit

A petroleum distillate used as a solvent and cleaner for alkyd and other resins, particularly for brushing applications.

Xylene

A petroleum distillate used as a solvent and cleaner for alkyd and other resins, it evaporates more quickly than white spirit and is therefore used for spraying, rather than brushing applications.

Zinc Chromate

Anti corrosive pigment

Zinc Phosphate

Anti corrosive pigment

Zinc Rich

Coating based on metallic zinc.