Polyester Powder Coating and the correct specification.

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Nick Dardalis


An excellent Article from Qualicoat on ‘Why Specify ‘Class 2’ and ‘Class 3’ Powders?’

Those in the aluminium supply chain will be aware of who Qualicoat are.  There are many who offer polyester powder coating in the market place, however not everyone is Qualicoat Approved and in powder coated aluminium windows and doors, they must be coated to the latest and relevant standards.

Qualicoat say:

In 1986 several national associations serving coaters of architectural systems formed the QUALICOAT organisation. Based in Zurich, their goal was to raise and standardise the quality powder coating across Europe. As a result coaters and manufacturers in many European countries have directly or indirectly become members of the QUALICOAT association. Today, membership extends beyond Europe with associations in Australia, South Africa and producers of coating materials in Asia, America and Europe.

In January 2001 the Qualicoat UK & Ireland Association was formed as a natural progression after several coaters in the UK applying for Qualicoat membership through the Zurich office.

Just by specifying ‘Qualicoat’ when requesting architectural powder coating, specifiers can be guaranteed that they get the very best quality and consistency of coating which is available from the Qualicoat UK & Ireland network of powder coat manufacturers, pre-treatment systems and applicators. Membership continues to rise and there is a growing number of companies in the UK and Ireland who open themselves up to independent inspection of powder, chemicals and finishes in order for the business to hold the coveted ‘Qualicoat Label’.

Most of powder coating undertaken in the UK and Ireland from Qualicoat members and independent powder coaters continues meet what is known under the Qualicoat Specification (12th edition) as ‘class 1’. These powders are high quality and offer excellent weathering and life expectancy, however, there are projects and situations where even higher durability coatings are required by the specifier.

By using Qualicoat approved powders, the approved method of pre-treatment and application, the chances of any coating failing due to corrosion or loss of adhesion during its expected life are virtually eliminated. All powder coatings, however, will age over time with abrasion from weather and UV. By specifying higher durability powders, the life expectancy can be extended for many years. Higher durability powders can be used on high rise applications, places where access could be difficult or where there is a particularly harsh environment.

Class 1 powders are tested to a 1 year Florida weather exposure test and must retain 50% of its original gloss level. Colour variation over the period is similarly tightly monitored within limits.

Class 2 powder is subject to a 3 year Florida weather exposure test and must retain a 75% gloss retention and Class 3 powder is subject to a 10 year Florida weather exposure test and must retain a 90% gloss retention. Similarly the colour variation is also tightly monitored within limits.

There has been a recognition by specifiers that the new formulations offer a more durable finish for architectural metalwork and Class 2 and 3 powder finishes are now being widely specified.

As a specifier, should higher quality finishes be required, contact a Qualicoat member and discuss the project in greater in detail – details of current members can be found on the associations website. Pretreatment and powder application is virtually the same for classes 2 and 3, the only change is the formulation of the powder which uses enhanced resin systems and higher grade pigments and stabilisers.