QUALICOAT - What is Behind this Detailed Specification For Architectural Powder Coating?

By Chris Mansfield - QUALICOAT Chair

Powder coating is as simple process right? Clean the aluminium, spray the electrostatically charged powder onto the earthed profile and bake. Yes, it may look good from the surface but will it last, well, no it won’t.

QUALICOAT, an Association built up of the architectural powder coating supply chain has spent decades working on a detailed worldwide Specification which, when followed precisely, offers unrivalled powder coat performance in any environment. The key to QUALICOAT’s success is that all licensed members, including applicators, powder manufacturers and pre-treatment systems providers of the Association are third party accredited to ensure that processes and products meet the strict requirements laid down in the Specification. Members do this willingly and pay for the inspections so that they can demonstrate compliance by maintaining a license to display QUALICOAT label of conformity.

All reputable companies in the architectural powder coating supply chain worldwide are licensed members of QUALICOAT. As a licensed applicator, regular production testing and recording is a prerequisite within the Specification. QUALICOAT licensed applicators must perform a full suite of mechanical and environmental tests on aluminium panels. In practice this means routine in‐house QC, for example, dry cross‐cut adhesion per ISO 2409, bend and impact tests and cure checks on every production batch. Independently, coated test panels, typically AlMg1 alloy 5005, 0.8–1 mm thick, are sent to the QUALICOAT approved laboratory, IFO, for third party evaluation.

These samples undergo accelerated weathering tests utilising equipment that offers condensation with intense UV which replicates long‑term outdoor Florida exposure, to track gloss and colour changes. Samples are also subject to corrosion tests that consists of acetic‐acid salt spray and surface durability trials including water spot and Martindale abrasion. These tests verify adhesion, flexibility and corrosion resistance against the four classes of powder formulations in the QUALICOAT Specification and therefore ensure the powder coating will perform over its intended lifetime.

Key to offering a robust powder coat finish, the powder coating must be cured using exact parameters, this is known as the ‘curing index’. The curing index quantifies the combined effect of time and temperature during powder cure, it is defined as a numerical index comparing the total cure experienced from the aluminium profile temperature versus time profile to meet the coating supplier’s prescribed cure schedule. Maintaining at least the manufacturer’s recommended cure index is critical because it ensures the powder has fully polymerised and achieved its intended properties including adhesion, hardness, and corrosion resistance. In practice, applicators verify or calculate the curing index by passing a calibrated temperature logger or test panel through the oven to record the stoving curve and comparing the area under that curve to the supplier’s cure curve.

QUALICOAT requires coaters to continuously monitor oven conditions and document them: for example, oven temperatures must be checked each shift and full stoving curves run on test panels at least twice weekly with all temperature records and curing-index data being logged in the plant’s quality control register for third party inspection. Powder formulations are submitted on a regular schedule to confirm ongoing compliance. For initial approval of any colour or new formulation, the powder manufacturer sends representative coated panels and material data for each qualifying colour and metallic formulation to the QUALICOAT approved testing laboratory.

After approval, the formulations must be retested in the lab bi-annually. Samples can be collected by QUALICOAT inspectors during routine audits or shipped by the coating maker, complete with full technical data sheets to the laboratory by the prescribed deadline. This program of periodic testing, together with triennial plant audits, catches any process drift and revalidates that the production of powder formulations meets QUALICOAT’s Specification. QUALICOAT requires all licensed applicators to use only approved pre-treatment systems listed in its current database, each of which must be supplied by a certified chemical company.

Applicators must follow the supplier’s instructions precisely, maintaining strict process control over parameters like pH, temperature, concentration, and contact time. They are obligated to keep detailed records of all pre-treatment bath parameters, replenishment data, and maintenance logs. In-house quality control tests, such as adhesion checks and coating thickness measurements, must be performed on every production batch. QUALICOAT’s third party inspectors, assess both documentation and the actual pre-treatment line operation. Non-compliance may result in warnings, required corrective actions, re-testing, or in serious cases, suspension or withdrawal of the QUALICOAT license.

Under QUALICOAT rules, any new aluminium pretreatment system must be formally submitted through the national association or QUALICOAT headquarters in Zurich with a complete technical dossier including technical data sheets, safety data sheets, and full process instructions. Appendix A6 of the QUALICOAT Specifications then prescribes a standardised test programme to be carried out in parallel by two QUALICOAT recognised, ISO 17025–accredited laboratories.

In practice the supplier prepares aluminium coated panels with a standard TGIC-free white powder, e.g. RAL 9010, which are subjected to all the Qualicoat mandated tests including mechanical tests, impact, adhesion, bend, cupping and aggressive corrosion exposures, neutral salt spray, humid SO₂, acetic acid salt spray, boiling water/pressure cooker, etc. The results are judged against the strict QUALICOAT criteria for example, no blistering and a maximum 4 mm corrosion undercut at a deliberate scribe.

Finally, the Assessment of Alternative Pretreatment Systems Working Group of QUALICOAT reviews the laboratory and field data and awards an “A‑xxx” approval if the system meets all requirements, this approval is valid for five years, after which, the pretreatment must be fully retested, including a two-year outdoor exposure for renewal.

So, the process of offering high quality powder coated profiles is complex, but clearly achievable given a dedicated supply chain that works closely together under the QUALICOAT Association. To ensure you get the benefit of this architectural powder coating, simply specify QUALICOAT in all your requirements for architectural aluminium. Should you wish to attend a members meeting and apply for membership of QUALICOAT please get in touch. All QUALICOAT UK & Ireland members are available to offer advice and can be found on the Association website at qualicoatuki.org