Source:
AkzoNobel Powder Coatings | Matt Bronze
To specify powder-coated products with confidence, it’s important to understand the basic process. There are two steps to powder coating: the cleaning and pretreatment of the aluminium, and the powder coating itself.
Pretreatment prepares the aluminium surface to ensure a strong bond and protect against corrosion. The process typically includes cleaning and an etch stage to remove contaminants and a subsequent passivation or conversion coating to ‘seal’ the surface of the aluminium, which also provides a ‘key’ for the adherence of the coating.
The powder coating is applied using the well-known method of spraying electrostatically charged fine polyester-based powders onto an earthed aluminium profile. Coated aluminium products are then heated to melt the powder, allowing it to flow and chemically cross-link into a sustainable coating. As the product cools, the coating sets, and the finish is complete.
THE POWER OF POWDER
Powders come in various grades, all offering a long-life expectancy, but higher grades or class of powder offer greater colour fastness when subject to UV light and better gloss retention. Gloss can be lost because of airborne abrasion as well as UV degradation.
Generally speaking, Class 1 powders are used in the UK, however, we’re also seeing an increasing number of projects opt for more resilient Class 2 ‘super durable’ powders. Class 3 is typically specified in harsh, more extreme environments such as the equatorial regions.
SPECIFICATION BEST PRACTICE
The size of a project can often determine the level of detail necessary within the specification. Often it is left to individual sub-contractors to arrange and supply coated goods, which can cause problems further down the line. While the same colour may be referenced, the powder on different sub-contracts may be provided by a different manufacturer – variables such as this can introduce shading issues between batches and risk overall performance and aesthetics.
The key is to discuss the finishes with the material and product suppliers and ideally have everything powder coated by the same applicator. If this isn’t possible, quality control can be achieved by agreeing the acceptable colour and gloss variance in advance.
SELECTING A POWDER APPLICATOR
The best way to address variation and mitigate risk is to specify QUALICOATcertified pretreatment and powder application through a licensed member. In this country, the global quality label organisation is represented by QUALICOAT UK & Ireland.
The association recognises the need for quality in the pretreatment, powders and finish; therefore, it licenses pretreatment system suppliers, powder manufacturers and powder coat applicators to ensure that quality levels are attained and maintained. QUALICOAT license holders are subject to random inspections twice a year to verify compliance with the QUALICOAT Specification. Licensed coaters who fail these third-party inspections will lose their license.
INSTANT VERIFICATION
Specifiers can verify QUALICOAT membership using the QR code on the member certificate – a new initiative for 2026. Users are redirected to the relevant record in the QUALICOAT QCT360 database, where the current validity status can be confirmed.
If valid, the user can access key information, including License Number and Type, Certification Year and Expiry. This additional transparency also helps specifiers identify established and experienced supply chain partners.
The most suitable specification for any architectural powder coating project, commercial or residential, should simply be ‘coated by a QUALICOAT-licensed applicator’. With the QUALICOAT
Specifications – 26th edition now live, we recommend clear and accurate referencing within project documentation to ensure supply chains are working to the latest edition. www.qualicoatuki.org