Qualicoat Class 2 Powder Coating for Aluminium: What Architects Need to Know.

Powder coating is the critical protective layer of every aluminium outdoor structure. Its quality determines how long the surface remains stable under UV radiation, moisture, and temperature cycling — without fading, cracking, or delamination. The Qualicoat quality mark classifies this quality in measurable terms.

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What Qualicoat is

Qualicoat is an international quality mark for the coating of aluminium and aluminium alloys. It is issued by the Qualicoat Association and monitored by accredited laboratories across Europe and worldwide.

The Qualicoat system distinguishes three classes:

Class 1: Standard outdoor coating. Suitable for normal climatic conditions, not for marine or heavily exposed environments.

Class 2: Enhanced weather resistance. Suitable for exposed locations, high UV loading, and coastal proximity (up to 10 km from the sea). The test requirements for gloss retention and colour stability after artificial weathering are substantially more demanding than Class 1.

Class 3: Maximum requirements, developed for marine environments within 2 km of the coast.

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Test requirements: Class 2 vs Class 1

The principal difference lies in the Florida weathering test (ASTM G154 or equivalent):

| Criterion | Class 1 | Class 2 | |---|---|---| | Florida weathering | 1 year | 3 years | | Permitted gloss reduction | ≤ 50% | ≤ 30% | | Colour deviation ΔE | ≤ 5.0 | ≤ 3.5 | | Chalking grade | max. 2 | max. 1 |

These are minimum requirements; actual performance of high-quality coatings typically exceeds these thresholds.

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GSB International as a parallel standard

Alongside Qualicoat, the GSB standard (Qualitätsgemeinschaft Schutz und Beschichtung) operates in Germany and Europe. GSB and Qualicoat differ in organisational structure, not technical intent. Both set comparable requirements for film thickness, adhesion, corrosion protection, and UV stability.

For tender specifications, GSB International and Qualicoat Class 2 are generally accepted as equivalent. PONARC systems are powder-coated with TIGER Coatings to GSB standard; Qualicoat certification is available on request.

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Film thickness and adhesion

Qualicoat specifies a minimum average film thickness of 60 µm for outdoor applications (no single reading below 40 µm). Class 2 does not specify a different thickness, but the powder formulation is more complex — higher binder content, UV-stabilised pigments.

Before powder coating, aluminium must be pre-treated: chemical degreasing and etching, followed by chromatisation or chrome-free passivation (REACH-compliant). Missing or deficient pre-treatment is the most common cause of adhesion failure in low-cost imported products.

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RAL colours and special colours

Any RAL colour can be produced in Qualicoat Class 2, provided the powder supplier holds approval for that colour. Intense tones (deep reds, dark blues) with high organic pigment content are inherently less UV-stable, and some manufacturers do not certify Class 2 for specific colours.

TIGER Coatings maintains a colour catalogue with explicit Class 2 approval. Specifiers writing non-standard RAL colours should confirm availability with the manufacturer before committing.

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Specification clause

For tender documents, the following wording can be used:

*"Powder coating to Qualicoat Class 2 or GSB International. Average film thickness ≥ 60 µm; no single reading < 40 µm. Pre-treatment by chemical degreasing, etching, and chrome-free passivation. Colour to RAL [number] or to approved sample. Evidence of certification by coater's certificate."*

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*PONARC systems are supplied with TIGER Coatings powder coating to GSB standard as standard. Technical details on request: ponarc.com/en/technology*