Growth in Class Two Powders
A great deal of work has been done by QUALICOAT over the last few years to understand the relationship between architectural aluminium and powder coating, the results of which are freely available in the current version of the QUALICOAT Standard which is constantly updated in ‘real time’. To gain a QUALICOAT licence, powder coaters must undergo both a stringent pretreatment & coating equipment review and crucially, a review of their production processes. Only when these meet the stringent requirements of QUALICOAT will a licence be granted. So who sets the standard? Members themselves set up in working groups from across the globe to set the bar high to simply be the best. So a QUALICOAT specification is an assurance that your coater cares about the quality they are providing.
With the recent introduction of QUALICOAT 3.0, where the aluminium itself has to meet stringent quality levels, the introduction of pre-anodisation and chrome free pretreatment systems, the sealing of the aluminium surface and the ‘key’ that these processes provide, ensures that the coating will remain in place for a very long time.
Weathering over time affects all finishes, this is especially relevant to buildings which are rarely cleaned on their exposed surfaces. Some materials, such as copper, the green patina effect once weathered, can be very pleasing. Corten exposed steel weathers to a dark rusty hue. Where specifiers want finishes that are intended to retain their original colours, finishes that fade or change over time would deemed to be unacceptable.
The formulation of organic coated surface treatments has advanced over the forty years that organic coating was first specified for architectural metalwork. Many of the original projects are still in use today with the coating still doing its job protecting the aluminium or steel substrate, but could have faded. Much of the current architectural organic coating in the UK uses ‘Class 1’ powders which offer excellent adhesion and long life.
Powders can be supplied in various grades of durability to suit a project application. Premium powder compositions use more expensive and robust materials to offer life expectancies well beyond thirty years and often similar to the life expectancy of the building itself. QUALICOAT has created quantifiable performance classifications for architectural organic coatings. In Europe there are three distinct classes of performance - Class 1, 2 & 3.
The key parameter to distinguish the performance of these Classes is their ‘weathering’ ability. That is to say, the ability to maintain a consistent colour and gloss level over time. To ‘weather’ well the organic coating must resist the deleterious effects of Light (in particular UVa & UVb), temperature and humidity. The globally accepted method for this ‘natural weathering’ test is conducted in Florida, USA. Sample panels are set for external exposure at a given angle 5° South. Powders are then classified over time exposure on the following performances:
Class 1 powders:
After twelve months exposure, less than 50% loss of gloss, and colour change between 2 and 6 delta units (subject to the colour). This pass criterion is commonly known as ‘1 year Florida’.
Class 2 powders:
After twelve months exposure, less than 25% loss of gloss, after twenty-four months, less than 40% loss of gloss and after thirty-six months, less than 50% loss of gloss. After threeyears colour change 2 to 6 delta units, dependent on colour. This testing criterion is commonly known as ‘3 year Florida’
Class 3 powders:
After three years, less than 20% loss of gloss, after seven years less than 45% loss of gloss and after ten years less than 50% loss of gloss – or commonly known as ’10 year Florida’.
Whilst Class 1 is the standard powder used across the UK, Class 2 organic coatings are increasingly being specified and offer greater durability against weathering. It is important to state that whilst Class 1 will weather, as shown in its class above, that does not mean that the finish fails to perform. Class 1 powder finishes have a life expectancy of thirty years or more.
The vast majority of high end powder coaters in the UK are now QUALICOAT approved and to ensure that specifiers get ‘QUALICOAT’ organic coatings, the Association recommends just adding the term ‘QUALICOAT Approved’ to the material specifications and the applicator of the architectural finish.
On new and refurbished buildings powder coated finishes will always come with a cleaning and maintenance regime from the company who coated the aluminium profiles. These will be minimal cleaning requirements and need to be adhered to as well as recorded when cleaning takes place. This will ensure the coated finish is maintained within the warranty wording and will help should there be any claim in the future.
Warranties vary in time and are dependent of the powder coat finish used and the location of the installation. For example, where the coating is close to the sea, a marine grade or QUALICOAT ‘Seaside’ specification for the coating must be used and the cleaning regime interval reduced to three monthly intervals as the atmosphere is more corrosive.
QUALICOAT UK & Ireland offer a basic guide which can be downloaded from their website. This can be referred to as where the original maintenance information has been mislaid and not available to refer to.
The global QUALICOAT standard continues to be incrementally revised with update sheets and a reprint of the standard every year. The standard is freely available for download at www.qualicoat.net. For details on the availability of various colours and finishes contact any QUALICOAT UK & Ireland member for more information. For updated information about the use and specification of QUALICOAT in the UK and Ireland, please visit the UK & Ireland Association website at www.qualicoatuki.org
QUALICOAT UK & Ireland with offices based in the Midlands is the National Association for QUALICOAT approved companies. QUALICOAT is a global quality label organisation committed to maintaining and promoting the quality of lacquering, painting and coating on aluminium and its alloys for architectural applications.
Please browse our website and should you have any questions about architectural powder coatings and the correct specification, please contact one of our local members or phone our office on the number below.
QUALICOAT UK & Ireland Chairman