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Powder coatings are generally a one coat finish, applied to suitably cleaned and pre-treated substrates. Some coatings such as metallics, require a clear coat to protect the metallic effect, although these are generally being replaced with the Dulux Precious® and Electro® Powder Coat Ranges which do not require a clear coat.
Powder coatings are a factory applied finish using specialised equipment. The equipment includes an electrostatic spray gun, spray booth and an oven to bake (or cure) the coating. On site application is not possible given the hot curing cycle required to fuse the coating.
Whilst powder coatings generally require no primers, it is important to provide a clean and pre-treated surface for the powder coat to adhere to. Metals that are planned for internal location can escape the need for pre-treatment; however it is advisable to provide some metal pre-treatment such as a phosphate finish to steel or chromate finish to aluminium to ensure maximum performance of the finish.
Unfortunately there is a myth that since powder coating is easier to apply than wet paints and retains a very hard finish, that powder coatings can withstand anything and everything. Indeed this carefree view has led to some disappointing applications of powder coatings. Powder coatings rely on a clean, pre-treated surface like any and every other coating.
Rusty metal deposits must be removed prior to powder coating, as over coating with powder will only mask what is fundamentally corroding metal. Powder coatings are terrific in resisting knocks and abrasions, chemicals and the effects of sun. However, if not cared for, the coating can show up scratches and film integrity loss.
Some powder coatings are designed specifically for contact with food but this is a specialised application that would be developed on a Made To Order basis. If this feature is required, you should contact Dulux for further information as the standard ranges of powder coatings are not suitable for contact with food.
Some powder coatings are specifically designed for electrical properties, but again, as with food grade coatings, this is specialised and you should contact Dulux for further advice.
Whilst powder coatings have the advantage over solvent based coatings of having a lower explosion point and therefore less flammable, caution should always be exercised with any electrical source such as mobile phones. Powder coatings are a fine organic dust which in high concentration, in the presence of air and an ignition source such as a mobile phone, could trigger a dust explosion.
The concentration of dust required to facilitate a dust explosion is significant, however, it is advisable to keep unnecessary equipment away from the booth and powder. As a precaution, Dulux recommends that mobile phones should be kept clear of these areas.
Powder coatings are produced by dry blending resins, pigments, additives and curing agents which are then extruded at elevated temperatures to melt and mix the ingredients. The material then becomes thick and viscous like a honey mixture which is cooled using super chilled water, before the material is crushed progressively to a fine, well defined particle size. Specialised equipment including rotary sieves and particle size measuring equipment is used to monitor and control the particle size distribution.
Dulux has two production facilities for powder coatings supplied to the local market. Our facility in Dandenong South, Victoria has four production lines with the capability of handling small batch sizes. The second facility is located in Auckland, New Zealand, which also has a variety of small and large equipment to cater for the extensive range of products manufactured by Dulux.
Not all colours behave the same during application or performance on site. Generally, light colours are ideal for more applications than other colour groups.
Light colours absorb little light because the white pigments help reflect the light. This reduces the heat up effect on parts. Dark colours absorb light and hence heat far more readily, which explains why dark cars are hotter than white cars in the sun. If heat is an important element in the design or use of your product, the effects of light and dark colours are an important consideration.
Bright colours behave differently again as they not only absorb light and remit this as brightness, the pigments are more readily damaged by ultra violet light reducing the life of the colour. Bright colours that include reds, oranges, greens and blues are recommended for applications where colour retention is not critical such as playground equipment and furniture.
Dulux Powder & Industrial Coatings offers a range of over 200 stock colours in either matt, satin or gloss finish. Our standard colour range includes colours to match the earthy tones of BlueScope Steel’s Colorbond Roofing range in matt and satin. To view our standard colour range click here.
Unlike paints which can be tinted to thousands or shades and finishes, powder coatings are formulated and factory produced. Powder coatings cannot be tinted successfully since the solid particles of each colour do not blend together, causing a mottled, speckled look when two different colours are mixed together. If you want to match a Dulux paint colour, we recommend you contact our Customer Service Team.
Paints and powder coatings have evolved from different industries; house paints from decorative applications and powder coatings from industrial uses. While Dulux has endeavoured to align colour names across industries, there are examples of colours e.g. Magnolia, which exist in both paints and powder coatings.
It is recommended when choosing a colour that a colour sample of each product be reviewed to ensure the colours chosen meet your needs.
Dulux can produce special colours and finishes on a Made to Order basis. Due to the nature of the manufacturing process, minimum quantity conditions limit the possibility of non-standard colours to typically large or ongoing projects. It is recommended when choosing colour, the powder coating colour be chosen first, as almost every powder coat finish can then be matched in a Dulux paint system.
There are various standards for powder application, covering the correct procedure for pre-treatment, powder application, testing and performance. The standards generally relate to the nature of the substrate. Please refer to our How to Specify page for further information.
Australian Standard AS3754 – Safe application by electrostatic spray outlines the procedures for safe application of powder coatings. Copies of this standard can be obtained from your local Standards Australia office.
Dulux recommends reference to the Australian Standard AS3754 – Safe application by electrostatic spray for correct handling of powder coatings. In general use of a dust mask, protective clothing and/or barrier creams are recommended.
There are various standards for powder coating depending on if the aspect of the standard focuses on safe application, metal finishing and end use application e.g. coatings for children’s toys or quality test standards. The standards generally relate to the nature of the substrate.
For aluminium substrates, Australian Standard AS3715 – Metal Finishing – Thermoset Powder Coating for architectural applications is recommended and most commonly referred to in Australia.
There are other standards which offer similar conditions, criteria and performance features such as British Standard BS6496 which is more commonly referred to in Asia and abroad.
For general metals including steel and galvanising, the Australian Standard AS4506-2005 for Metal Finishing – Thermoset powder coatings is recommended.
The British Standard BS6497 has been referred to quite considerably in the past as this deals directly with the powder coating of galvanised metal substrates.
The most recognised standard of durability of coatings is the AAMA standards. The AAMA standards are based on performance criteria set out by the Architectural Aluminium Manufacture’s Association, from where the reference to AAMA originates. The three AAMA standards used to specify powder coatings are below;
See How to Specify page to find out more information regarding specifying the correct AAMA Standard.
There are many standards established simply to outline an agreed standard for measuring a coating’s performance. Examples of common tests might be gloss measurement, adhesion of coatings, weathering performance, hardness, chemical resistance or stain resistance. Among the many standards are the Australian Standard AS1580 – Paints and related materials – Methods of Test and British Standard BS3900.
Copies of standards can be purchased from your local Standards Australia office in major capital cities or by accessing one SAI Global here.
Powder coating storage lives vary according to the technology and the storage conditions. Generally Dulux recommend 2 years before the powder is re-tested to confirm no degradation in film properties. If the powder has become lumpy and absorbed moisture, the material may be sieved and then fluidised for 10 minutes to condition the powder in preparation for application.
If the powder has become too lumpy and solid, it would suggest some pre-reaction of the powder which cannot be reversed nor corrected. Some technologies may have shorter storage periods, but these are generally outlined in the technical data sheets and/or product packaging.
This practice has been used quite often in the industry and the rationale for reducing powder dust is admirable. However, placing cardboard cartons inside ovens produces the risk of a fire which can have devastating results. There have been examples of fires at powder coating facilities in Australian where operators placed waste powder cartons in the oven which caused a fire.
Aside from the loss of production and equipment from the fire, not to mention the safety risk to staff, most insurance companies will not cover such incidents.
Powder coating are not classified as dangerous goods. There are no solvents in powder coatings which simplifies the transport and storage of powder coatings.
Everything relative, powder coatings are considered far more environmentally friendly that wet paints or anodising. Powder coatings use no solvents which are harmful to the environment. Over sprayed powder can be recovered, sieved and then reapplied to other products which helps reduce waste powder.
Whilst some Municipal Councils restrict the waste disposal sites for powder coatings, the products have limited to no leaching effect in dry form and no leaching effect in the cured form. Given the very good durability of powder coatings, the need to recoat the sits is less common, meaning fewer burdens on the environment in the future.
Powder coatings can be safely cleaned up via a brush and spade or a vacuum cleaner, provided the amount of powder is not excessive. For large spills, the powder should be shovelled into a plastic bag inside a carton and tipped into the box for easy disposal.
The rules and regulations for powder waste disposal vary across states and regional councils. In many instances, powder coating is suitable for land fill; however it is important to contact your local council and/or Environmental Protection Agency office to clarify local requirements for waste disposal.
As a rule, ensuring waste powder is placed in securely sealed packs with no leaks is important to limit nuisance dust. This will ensure that powder is not emitted to the atmosphere when loaded to the waste truck on your premises and hence avoid subsequent complaints from neighbours.
The effects of pollution, dirt, grime and salt deposits can all accumulate on a powder coated surface over time. To extend the effective life of powder coatings and fulfil any warranty requirements that may exist, a simple regular maintenance program should be implemented for the removal of residues. As a general rule, all powder coated surfaces should be cleaned every six months.
However in areas where pollutants are more prevalent, especially in coastal or industrial regions, a cleaning program should be carried out on a more frequent basis. To clean a powder coated surface, customers should carefully remove any loose deposits with a wet sponge and then use a soft non-abrasive brush or cloth in combination with a mild household detergent solution to remove dust, salt and other residues. Finally rinse all powder coated surfaces with clean water.
See our Care & Maintenance page for further information.
From the perspective of adhesion and film integrity, correctly applied and pre-treated powder coated metal can and has lasted since it was first applied more than 40 years ago. Powder coatings are considered extremely resilient and have been a coating of choice for use on gas and oil pipelines which are buried in earth or underwater. Powder coatings have also been used on automotive and appliances given their excellent chip resistance, hardness and chemical resistance.
From the perspective of resistance to light and UV degradation, some powder coatings are outstanding, being used on major buildings such as our Duratec® and Fluoroset® ranges. The standard and most common powder coatings are designed for general use and applications. Standard powder coatings offer good weathering resistance, excellent film integrity and hardness.