Technical | Glossary
Glossary of terms - please click on a heading for information on the term.
A
Acrylic paint is fast-drying paint containing pigment suspended in an acrylic polymer emulsion. Acrylic paints can be diluted with water, but become water-resistant when dry. Depending on how much the paint is diluted (with water) or modified with acrylic gels, mediums, or pastes, the finished acrylic painting can resemble a watercolor or an oil painting, or have its own unique characteristics not attainable with the other media.
The property of a coating to stick to its substrate. The most common test for adhesion is the cross hatch test.
One of a range of physical or mechanical tests to measure adhesion. Includes cross hatch, and pull off.
In chemistry organic compounds are divided into aliphatic and aromatic – meaning containing benzene or not. In paint systems refers to the two main types of polyurethane. Aliphatics have good gloss retention, but poorer chemical resistance than aromatics.
Coating system designed to resist graffiti. Most often aromatic polyurethanes. Now available from Highland with a solvent free cleaning solution. These solutions have passed the UK standard for anti graffiti, set by the London Underground.
Term used in standards to describe what a coating looks like. Very subjective, and impossible to measure, but can often be a cause for rejection. One person’s idea of good appearance rarely matches another persons.
An automated system of painting on a production line such as automotive manufacture. Involves the dipping of the whole item in an acidic solution containing diluted paint (5%) which etches and applies the paint. There is no electricity or charge involved, and in this way is similar to electroless plating. Used most often in high volume manufacturing, where the same colour is used for long periods. Unsuitable for jobbing.
B
The main constituent of a paint that binds together the pigments (see “pigment”) and other component parts. Binders are often Epoxy silicate or Acrylic. (see each of these)
A quality issue in coatings where small areas delaminate from the substrate, but do not perforate. Mimics blistering of the skin by heat. Sometimes contain water underneath.
C
A chemical compound added to coatings to bring about a chemical reaction that cures the coating.
A surface degradation of the coating, usually associated with weather and UV exposure, where the coating turns to a chalk like surface.
The resistance of a coating to a wide range of chemicals.
Paint system with a rubber base. Low resistance to heat (70C), and to solvents, but a high resistance to acids and alkalis.
A quality fault in painting where small areas do not get covered.
Coal tar is a brown or black liquid of high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal is carbonized to make coke or gasified to make coal gas. It used to be (and still occasionally is) used in paint manufacture for high corrosion applications. It is almost akin to painting something with tar. Coal tar products are used in medicines to treat diseases such as psoriasis, and also as animal and bird repellents, insecticides, animal dips, and fungicides. Coal tar creosote is the most widely used wood preservative in the United States. Virtually all wooden railroad ties and telephone poles in use are treated with creosote to retard rotting. Coal tar, coal tar pitch (pitch), and coal tar pitch volatiles are used for roofing, road paving, aluminum smelting, and coking. See also creosote
Any organic or inorganic thin layer of material on a substrate, in order to protect or colour or change the appearance of that substrate.
Strictly the wavelength of light being received by the eye. Most items of colour exhibit
this facet because they absorb some wavelengths, reflecting others, giving rise to a
characteristic the brain thinks of as colour.
The human eye can differentiate thousands of
colours, but we are not all equal in this respect. In practical terms this means that some
people are far better at colour differentiation than others.
System of measuring colour to avoid the discretion and variation that the human eye exhibits in attempting to measure colour. Can be as simple as matching colour of a coating against a known standard swatch, or as complicated as measuring the wavelength of light reflected from a coating.
Consideration of whether primers undercoats and top coats can be used together. Example: an alkyd primer cannot be used with a chlorinated rubber top coat.
As it implies, cracks in coatings. Usually leads to delamination, and eventual full failure of the coating.
Creosote is the name used for a variety of products: wood creosote, coal tar creosote, coal tar, coal tar pitch, and coal tar pitch volatiles. These products are mixtures of many chemicals such as polycyclic aromatic hydrocarbons (PAHs), phenol, cresols created by high temperature treatment of beech and other woods, coal, or from the resin of the Creosote bush.
A chemical process where a coatings molecules join up to form long chain molecules Covalent bonds linking one polymer chain to another. They are the characteristic property of thermosetting polymer materials.
A test for adhesion in coatings. Consisting of a series of scribes at accurate spacing, through the coating to the substrate, followed by the use of calibrated sellotape to try to pull off the coating.
A test of resistance to deformation. Coating an substrate are indented to 5mm, and adhesion observed.
The process of converting a coating from an applicable state (liquid or powder) to a solid uniform continuous coating.
D
A coating to resist the ingress of moisture, often in buildings.
Any coating designed or intended to be pleasing to look at. Often to enhance the appearance of the substrate.
A drying oil is an oil which hardens to a tough, solid film after a period of exposure to air. The term "drying" is actually somewhat of a misnomer - the oil does not harden through the evaporation of water or other solvents, but through a chemical reaction in which oxygen is absorbed from the environment (autoxidation). Drying oils are a key component of oil paint and many varnishes. Some commonly used drying oils include linseed oil, tung oil, poppy seed oil, perilla oil and walnut oil.
E
Always the weakest area of all wet coat applications due to the nature of bonding is where to two sedges meet. This is therefore the first area likely to fail, and corrode. This is not the case with hot dip galvanizing. Edge Protection is a process offered by galvanizing which ensures overlapping coatings remove this weakness, making edges as strong, if not stronger than surfaces.
Electrolytic protection is the chemical reaction between substrate and coating in a sacrificial manner to protect the substrate, should water penetration take place due to mechanical damage. In Hot Dip Galvanizing this creates a self healing coating.
A system of applying coatings where the coating particles (dry powder or droplets of liquid) are electrostatically charged to cause them to temporarily adhere to the substrate until curing.
A generic term for paints which are water borne polymers.
In chemistry, epoxy or polyepoxide is a thermosetting peroxide polymer that cures (polymerizes and crosslinks) when mixed with a catalyzing agent or "hardener".
A highly abrasion, heat, solvent and water resistant primer.
In coating terms, the outside of a building or any components that are stored in the weather.
F
Test of resistance to deformation. A calibrated falling weight falls a set distance, exerting a known force. Adhesion of the coating is observed during the deformation.
Filiform corrosion, sometimes also called "wormtrack corrosion", is a very characteristic type of corrosion that occurs under some coatings in the form of randomly distributed threadlike filaments. It most commonly occurs on aluminum alloys coated with an organic coating, but other examples exist.
A test to measure resistance to filiform corrosion.
Quality issue in coatings where areas of coating fall off the substrate to the entire thickness of the coating, revealing the substrate. Leads to entire failure of the coating.
A coating which has highly reflective properties, often in bright colours. Often used in safety or warning applications.
A coating that is compatible with the food industry.
Coating which resists the formation of fungus growth. Coating contains fungicides.
Fusion bonded epoxy coating, also known as fusion-bond epoxy powder coating and commonly referred to as FBE coating, is an epoxy based powder coating that is widely used to protect various sizes of steel pipes used in pipeline construction, concrete reinforcing rebar and on a wide variety of piping connections, valves etc. from deterioration due to corrosion. FBE coatings are thermoset polymer coatings. They come under the category of 'protective coatings' in paints and coating nomenclature. The name 'fusion-bond epoxy' is derived from the way of resin cross-linking and their method of application which is different from that of a conventional liquid paint. FBE coatings are in the form of dry powder at normal atmospheric temperatures. The resin and hardener parts in the dry powder remain unreacted at normal storage conditions. At typical coating application temperatures, usually in the range of 180 to 250°C (360 to 480°F), the contents of the powder melt and transform to a liquid form. The liquid FBE film "wets and flows on to" the steel surface, on which it is applied, and soon becomes a solid coating by chemical cross-linking, assisted by heat. This process is known as “fusion bonding”. The chemical cross-linking reaction taking place in this case is "irreversible", which means once the curing takes place, the coating cannot be converted back into its original form by any means. Application of further heating will not “melt” the coating and thus it is known as a “thermosetting” coating.
G
Reflective property. In coatings it is normally measured in % reflectivity referred to a standard. “Matt” is about 10-30% gloss, “Satin” about 50-60%, and “gloss” is 80-100% gloss. Specifying gloss using terms like “satin” can lead to misunderstandings. If this attribute is important, specify as % gloss.
Test using an instrument that measures the amount of light reflected at 60 degrees to the angle of incidence. Units are % gloss.
H
A coating effect where the surface appears to have been hammered. Brand names include Hammerite.
An additive to a coating formulation that brings about curing, or hardening. In coatings terms, means areas where industry occurs, and will require more protective coatings than say residential, or rural environments.
Test to see how well a coating handles humidity. Conducted inside a test cabinet of calibrated humidity and temperature for typically 1,000 hours. Test result is usually stated in hours to coating failure.
I
An intumescent is a substance which swells as a result of heat exposure, thus increasing in volume, and decreasing in density. Intumescents are typically used in passive fire protection and require listing and approval use and compliance in their installed configurations in order to comply with the law.
L
In a general sense, lacquer is a clear or coloured coating that dries by solvent evaporation and often a curing process as well that produces a hard, durable finish, in any sheen level from ultra matte to high gloss and that can be further polished as required. Despite the similarities in their names, Shellac and lacquer are not the same, and are not related. Shellac is an insect resin secreted by the Lac bug, which lives in India and Southeast Asia. Shellac’s solvent is alcohol. Lacquer is based on cellulose nitrate (nitrocellulose) with resins added to make it less brittle, and nitrocellulose is made from wood pulp. Lacquer’s solvent is lacquer thinner. While both lacquer and shellac are traditional finishes, lacquer is more durable than shellac.
Consisting of several layers. Intentional laminations are multi layered coatings, usually well adhered to each other. Can also refer to unintentional layers where there should not have been any, and separating from each other destroying the coating.
Latex refers generically to a stable dispersion (emulsion) of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic. Latex as found in nature is the milky sap of many plants that coagulates on exposure to air. It is a complex emulsion in which proteins, alkaloids, starches, sugars, oils, tannins, resins and gums are found. In most plants, latex is white, but some have yellow, orange, or scarlet latex.The word is also used to refer to natural latex rubber; particularly for non-vulcanized rubber. Such is the case in products like latex condoms and latex clothing. It can also be made synthetically by polymerizing a monomer that has been emulsified with surfactants.
Some paints used to contain lead compounds as pigments. The reason was good stability of colour, and bright colours available, but health considerations mean that virtually no lead paints are now made. Red Lead is the term used for some primers, but most now actually are iron oxide, not lead oxide as pigment.
A coating which glows in the dark.
M
The marine environment is subject to salt spray effect, which is highly corrosive to mild steel. Specific coating applications can be used to provide both aesthetic and structural longevity to mild steel structures under such exposure conditions. Highland can issue specific guarantees for such circumstances.
Melamine resin or melamine formaldehyde (also, incorrectly, melamine) is a hard, thermosetting plastic material made from melamine and formaldehyde by polymerization. This plastic is often used in kitchen utensils or plates (e.g., Melmac) and is the main constituent in high pressure laminates such as Formica and Arborite and of laminate flooring. Melamine tile wall panels can also be used as whiteboards. Melamine resin is sometimes used in paint manufacture.
Coatings containing various metals dusts, which give an enhanced appearance, but in some cases enhanced performance in abrasion or impact resistance.
Abbreviated to MIO. From Mica, a silicate mineral often used for its flat plate-like appearance, and added to paints to form small platelets in the paint that give increased imperviousness to moisture ingress through the paint. (Mica is often the material used to hold the element wires in toasters)
A pre-treatment system for galvanized steel, prior to painting. The word “Mordant” (to change the colour of) comes from the fact that the steel changes colour from silvery grey to dark grey-black after pre-treatment. Sometimes called “T-Wash”
A test of resistance to drops of cement mortar on a coating. Particularly relevant in the construction industry where bricklaying mortar can splash onto coated metal joinery, potentially staining the coating. The test involves specified strength mortar dropped onto coated samples and left for 24 hours.
A problem when some paints are applied too thickly and dry in a similar fashion to mud with shrinkage cracks appearing. Ethyl silicate can suffer from this.
N
Nitrocellulose lacquer was used as a finish on guitars for most of the 20th century and is still used on some current applications. Manufactured by (among others) Dupont, the paint was also used on automobiles sharing the same color codes as many guitars, primarily Fender brands of guitars. Nitrocellulose lacquer is also used as an aircraft dope, painted onto fabric-covered aircraft to tauten and provide protection to the material.
A rough coating to enhance non-slip properties for walkways, steps and other walkway applications. Most often achieved by the addition of a granular material such as plastic chips before the coating cures. Not available in powdercoated finishes.
O
As name implies, a coating resistant to oils etc.
A coating failure where the surface of the coating is dimpled similar to the surface of an orange, hence the name. It is an aesthetic issue, not a performance issue, and in many applications is acceptable.
P
A coating that contains light refracting material to give a rainbow effect similar to pearl, sea shell etc. An aesthetic effect.
A pigment is a material that changes the color of light it reflects as the result of selective color absorption. Many materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at ambient temperatures. Pigments used commonly include: Micaceous iron oxide, titanium dioxide, Zinc phosphate, zinc oxide, silicate, zinc metal. Pigments previously used (but not now) include lead, calcium plumbate.
Plastic is the general term for a wide range of synthetic or semisynthetic polymerization products. They are composed of organic condensation or addition polymers and may contain other substances to improve performance or economics. There are many natural polymers generally considered to be "plastics". Plastics can be formed into objects or films or fibers. Their name is derived from the fact that many are malleable, having the property of plasticity.
A polyamide is a polymer containing monomers of amides joined by peptide bonds. These are sometimes used as an additive to assist in the curing reaction of some paint systems.
Polyethylene is a polymer consisting of long chains of ethylene. It is sometimes incorporated into paint systems
In polymer chemistry, polymerization is a process of bonding monomers, or "single units" together through a variety of reaction mechanisms to form longer chains named polymers. Polymers exist as a variety of 3-dimensional shapes, each with specific individual properties relevant to the monomers or reaction mechanisms they are formed from.
An aromatic polymer made from the aromatic monomer styrene, a liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry. Polystyrene is a thermoplastic substance, normally existing in solid state at room temperature, but melting if heated (for molding or extrusion), and becoming solid again when cooling off.
A polyurethane, commonly abbreviated PU, is any polymer consisting of a chain of organic units joined by urethane links. Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. These materials include low density flexible foam used in upholstery and bedding, low density rigid foam used for thermal insulation, soft solid elastomers used for gel pads and print rollers, and hard solid plastics used as electronic instrument bezels and structural parts. Polyurethanes are widely used in high resiliency flexible foam seating, rigid foam insulation panels, microcellular foam seals and gaskets, durable elastomeric wheels and tires, electrical potting compounds, high performance adhesives and sealants, Spandex fibres, seals, gaskets, carpet underlay, and hard plastic parts.
Polyvinylchloride, commonly abbreviated PVC, is a widely used thermoplastic polymer. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in construction. As a building material, PVC is cheap, durable, and easy to assemble. In recent years, PVC has been replacing traditional building materials such as wood, concrete and clay in many areas. Despite claims that PVC production negatively affects the natural environment and human health, it is still widely used. Sometimes incorporated into paints.
A simple test to check the permeability of a coating. Boiled in a pressure cooker for 2 hours at 100 kPa the sample may discolour, but there should be no lack of adhesion.
This is the process a substrate must go through to ensure the bond between substrate and coating is strong, and to the relevant British Standard. Typically this is the key to success in any application, and is ideally best carried out in a factory controlled environment, to the British Standard.
Primer is a preparatory coating put on materials before painting. Priming ensures better adhesion of paint to the surface, increases paint durability, and provides additional protection for the material being painted.
A test of adhesion where a small device is glued to the coating, then pulled off. The force required to break the coating away from the substrate is the measurement, and units are pascals, usually MPa. (MegaPascals)
S
A test subjecting a sample of coating to a continuous salt spray. The spray might be neutral, acid or alkali. Results stated as hours to failure, or hours without failure. (eg 1000 hours salt spray.)
An overcoat, normally clear, for protection of the coating beneath. Clear polyurethane is sometimes used in this way.
The main purpose of the solvent is to adjust the viscosity of the paint. It is volatile and does not become part of the paint film. It can also control flow and application properties, and affect the stability of the paint while in liquid state. Its main function is as the carrier for the non volatile components. Water is the main solvent for water based paints. Solvent based, sometimes called oil based, paints can have various combinations of solvents as the vehicle, including aliphatics, aromatics, alcohols, and ketones. These include organic solvents such as petroleum distillate, alcohols, ketones, esters, glycol ethers, and the like. Sometimes volatile low-molecular weight synthetic resins also serve as diluents.
The surface of the object being coated. For the purpose of this directory, steel or aluminium.
A test of ability of a coating to withstand harsh environments. Sample is enclosed in sulphur dioxide gas.
T
Highland does not use TGIC powders in its coating applications. Triglycidyl isocyanurate, TGIC, is used as a curing agent in powder coating paints applied to industrial and household products, such as car parts, washing machines and refrigerators as well as architectural finishes. It is also used as a solder mask in the manufacture of printed circuit boards. As a Category 2 mutagen, TGIC and products containing it are now subject to the additional control measures applied by the Control of Substances Hazardous to Health Regulations 2002 to substances classified as Category 1 or 2 carcinogens or mutagens.
A thermoplastic is a plastic that melts to a liquid when heated and freezes to a brittle, very glassy state when cooled sufficiently. Most thermoplastics are high molecular weight polymers. Thermoplastic polymers differ from thermosetting polymers (Bakelite; vulcanized rubber) as they can, unlike thermosetting polymers, be remelted and remoulded. Theromplastic powdercoating includes “plastic coating”.
Usually refers to the thickness of a coating. A common unit is the micron, (one thousandth of a millimetre – 0.001 mm). In the USA the unit mil is used, (A thousandth of an inch - 0.001 inches or a milli-inch)
Thixotropy is the property of some fluids to show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite amount of time to attain equilibrium viscosity when introduced to a step change in shear rate. In ordinary language, a thixotropic liquid is one that get thinner with stirring.
Titanium dioxide is the most common pigment used in paints, especially because it is pretty inert and is bright white. Almost all white paint is pigmented with this. Its formed from a common mineral mined extensively worldwide.
U
A curing process using ultra violet light.
Resistance to ultra violet light. Sunlight contains UV, which causes skin cancer, and attacks non-resistant paints.
V
Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. Varnish is traditionally a combination of a drying oil, a resin, and a thinner or solvent. Varnish finishes are usually glossy but may be designed to produce satin or semi-gloss sheens by the addition of "flatting" agents. Varnish has little or no color, is transparent, and has no added pigment, as opposed to paints or wood stains, which contain pigment and generally range from opaque to translucent. Varnishes are also applied over wood stains as a final step to achieve a film for gloss and protection. Some products are marketed as a combined stain and varnish.
Viscosity is a measure of the resistance of a fluid to being deformed by either shear stress or extensional stress. It is commonly perceived as "thickness", or resistance to flow. Viscosity describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. Thus, water is "thin", having a lower viscosity, while vegetable oil is "thick" having a higher viscosity.
Abbreviation for Volatile Organic Compounds. Volatile organic compounds (VOCs) are organic chemical compounds that have high enough vapour pressures under normal conditions to significantly vaporize and enter the atmosphere. A wide range of carbon-based molecules, such as aldehydes, ketones, and hydrocarbons are VOC's. Many paint solvents or thinners are VOC compounds. UK law demands that painters who use VOC containing coatings are under increasing pressure to collect and either destroy or recycle the VOC. The regulations have been made tighter in 2004, 2007 and will be even more restrictive in 2010 to the extent that many applicators of solvent based paint systems will not be able to operate without extensive additional equipment. Outdoor (on-site) applications of some coatings will no longer be possible.
W
A Polymer Alloy Coating available from Highland that performs as a warm to touch coating solution, suitable for disabled handrails, etc.
Coatings where water is the solvent or the thinner.
Coatings that are impervious to water. Very few coatings are truly waterproof. Hot dip galvanizing is.
