Guide to Qualicoat and Powder Coating Standards for Aluminum

Surface Treatment Technologies II: Qualicoat and Powder Coating Standards

 

Electrostatic Powder Coating is an eco-friendly finishing method that offers unlimited color options for aluminum profiles. However, the quality of the coating is measured not just by its color, but by its resistance to external environmental factors. The global authority auditing this quality is the Zurich-based Qualicoat organization. At Mertcan Metal, ensuring our supply chain consists of Qualicoat-licensed facilities means that our quality is officially certified.

1.1 Thickness Requirements per Qualicoat 2024 Specifications

Coating thickness determines the strength of the protective barrier. According to Qualicoat's 2024 "Master Version" specifications for architectural profiles:

• Class 1, Class 1.5, and Class 2 Powders: The average coating thickness on the significant surface must be at least 60 microns (µm).
• Minimum Value Rule (80% Rule): No single measurement can be less than 48 microns (80% of the required value). If a spot measurement of 40 microns is found, the batch is rejected.
• Class 3 Powders: Minimum average thickness is 50 microns.
• Seaside Systems (Dual Coat): For coastal projects utilizing a Primer + Topcoat system, the total thickness must be at least 110 microns.

1.2 Critical Test Methodologies

There are two fundamental tests to determine coating integrity:

1. Adhesion Test - ISO 2409 (Cross-Cut Test):
• A lattice pattern with 1mm or 2mm spacing is cut into the coating down to the metal substrate using a specialized multi-blade cutter.
• Standardized tape is applied to the cut area and removed abruptly.
• Evaluation: For Qualicoat approval, the result must be GT0 (Grade 0). The edges of the cuts must be completely smooth; no detachment of coating flakes is permitted at intersections or squares. Even GT1 (minimal detachment) is unacceptable.
2. Impact Test - ISO 6272:
• A weighted metal indenter is dropped from a specific height (2.5 Nm energy) onto the reverse side of the coated surface.
• There must be no cracking or detachment of the coating. This measures the flexibility and curing quality of the powder.

1.3 Qualicoat Durability Classes

In powder coating, the term "Class" refers to UV resistance, not color.

• Class 1 (Standard): Withstands 1 year of natural weathering in Florida (high UV and humidity). Sufficient for standard architectural projects.
• Class 2 (Super Durable): Requires 3 years of resistance in the Florida test. After 3 years, gloss retention must be at least 50%. Highly recommended for skyscrapers, shopping malls, the Mediterranean coast, and Middle Eastern projects. Class 2 powders are 3 times more resistant to fading than Class 1.