Powder coatings are generally a one coat finish, applied to suitable cleaned and pre-treated substrates. Some coatings, such as metallic's, require a clear coat to protect the metallic effect, although these are generally being replaced with the Dulux Pearl range which does not need 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 coating 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 so much easier to apply than wet paints, and retains a very hard film, 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 the sun, but if not cared for, the coating can show up scratches and perhaps film integrity loss.
Some powder coatings are designed specifically for contact with food but this is a specialised application, and if this feature is required, you should contact Dulux for further information. 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.
Powder Coatings are produced by dry blending of 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 new 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 size equipment to cater for extensive range of products manufactured by Dulux.
Not all colours behave the same during application or performance on site. In general, 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 is important consideration.
Bright colours behave differently again. Bright colours not only absorb light and remit this as brightness, but the pigments are more readily damaged by the ultra violet light reducing the life of the colour as we know that colour. Bright colours, which include, reds, oranges, yellows, bright greens and blues are recommended for applications where colour retention is not critical such as playgrounds and furniture.
The Dulux Powder Coatings Colour Selector offers a range of over 120 stock colours in either matt, satin or gloss finish. Our colour range includes colours to match the earthy tones of the BlueScope Steel’s Colorbond Roofing range in matt and satin.
Unlike paints which can be tinted to thousands of shades and finishes, powder coatings are formulated and produced in a factory. Powder coatings cannot be tinted successful since the solid particles of each colour do not blend together, causing a mottled, speckled look when two different colours are mixed together.
Paints and powder coatings have evolved from different industries; house paints from the decorative applications and powder coatings from industrial uses. Whilst Dulux has endeavoured to align colour names across the industries, there are examples of colours, such as Magnolia, which exist in both paints and powder coatings, but are different in shade and strength. 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, but due to the nature of the manufacturing process, minimum quantity conditions limit the possibility of special colours to typically large or ongoing projects. It is recommended that when choosing colour, the powder coating colour be chosen first, as almost every powder finish can then be matched in a Dulux paint system.
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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. For more information on standards, refer to the Standards section of FAQ’s.
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 recommend 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.
Whilst powder coatings have the advantage over solvent based coatings of having a lower explosion point and therefore is less flammable, caution should always be exercised with any electrical source such as mobile phones. Powder coating is 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 store. As a precaution, Dulux recommends that mobile phones should be kept clear of these areas.
There are various standards for powder coatings, depending on if the aspect of the standard focuses on safe application, metal finishing, and end use application such as coatings for children’s toys or quality test standards. This section of FAQ’s outlines some of the most common standards.
For aluminium metals, Australian Standard AS3715 “Metal Finishing – Thermoset powder coatings 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 the British Standard BS6496, but this standard is more commonly referred to in Asia and abroad.
For general metals including steel and galvanising, the Australian Standard AS4506 “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, and has been in existence for much longer than the Australian standard AS4506.
The most recognised standard for durability of coatings is the AAMA standards. The AAMA standards are based on performance criteria set out by the Architectural Aluminium Manufacturer’s Association, from where the reference to AAMA originates. The AAMA standards cover 3 years Florida resistance (AAMA 2603-02), the 5 years Florida resistance (AAMA 2604-10) and the 10 years Florida performance (AAMA 2605-11) which only Fluoropolymer coatings such as Fluoroset and Fluoroset FP meet.
What are some standards which outline some common performance test and quality assurance test standards?
There are many standards established simply to outline an agreed standard for measuring 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 series AS1580 and the British Standard series BS3900.
Copies of standards can be purchased from your local Standards Australia office in major capital cities or by accessing one of these appropriate websites.
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 or 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. The same conditions for re testing the powder apply as above.
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 Australia where operators placed waste powder cartons in the oven which caused a fire. Aside from the loss of production and equipment from fire, not to mention the safety risk to staff, most insurance companies will not cover such incidents.
Powder Coatings are not classified dangerous goods. There are no solvents in powder coatings which simplifies the transport and storage of powder coatings.
Everything is relative, and powder coatings are considered far more environmentally friendly than 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 on site is less common, meaning fewer burdens on the environment into 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 Local Council and/or Environmental Protection Agency offices 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 you will 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.
This is a very common question. 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, be a coating of choice for use on gas or oil pipelines which are buried in the earth or underwater. Powder coatings are used on automotive and appliances given their excellent chip resistance, hardness and or chemical resistance.
From the perspective of resistance to light and UV degradation, some powder coatings are outstanding, being used on major building such as Duratec and Fluoroset FP.
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 very good hardness