Why coastal environments need a different approach
At C&O we are regularly asked about whether a building near the sea needs a different powder coating approach. The honest answer is that it depends, but often, yes.
Powder coated aluminium performs well in most environments when it is specified and applied correctly. It will look good and protect the metal for a long time but in coastal areas salt carried in the sea air settles on the surface which can cause damage.
In most cases salt in the air won’t be a problem, particularly if the powder coated metal is regularly maintained, but where the surface of the aluminium has not been prepared deeply enough salt can work its way into the metal causing corrosion. When this happens, the powder coating doesn’t just fade, it starts to separate from the aluminium and by the time it’s visible, the damage has been done.
Here’s what most people don’t realise when they first ask the question. The coating itself is rarely the problem regardless of colour or finish. What causes it is the preparation of the metal underneath, the aluminium needs to be cleaned and etched deeply enough before it is powder coated to be able to withstand an aggressive coastal atmosphere.
Qualicoat Seaside Specification is designed to solve this problem.
What is Qualicoat Seaside?
Qualicoat is the independent quality standard that governs architectural powder coating on aluminium in the UK. To be certified companies like C&O need to have their processes, pre-treatment systems and powder suppliers independently audited on a regular basis.
The Seaside Specification was introduced in 2008 by Qualicoat specifically for coastal and aggressive environments and it addresses the pre-treatment process itself rather than the coating.
Here’s how the two differ. Standard Qualicoat pre-treatment requires the aluminium to be etched to remove a minimum of 1 gram per square metre of metal from the surface. This cleans the aluminium and creates a stable base for the coating to bond to. Seaside specification doubles this to 2 grams per square metre. The deeper etch removes more of the trace elements and contaminants in the metal surface, leaving a cleaner and more stable substrate that is better prepared for the kind of atmosphere a coastal building will face over its lifetime. For both standards the powder used is the same.
To be able to offer Qualicoat Seaside to customers an applicator like C&O needs to be able to consistently demonstrate they can achieve the required etch level and submit samples for independent corrosion testing before they are granted certification which is then regularly audited to ensure standards are maintained.
When should you specify Qualicoat Seaside?
The starting point is distance from the coast. Qualicoat advise that Seaside should be specified for projects within 5km of the coast or a tidal estuary. Whilst this is a good place to begin the location of the building also needs to be considered in the decision making process. A building facing the sea at height on an exposed headland is in a very different position to a sheltered site three kilometres inland. Wind direction, building height and how directly the aluminium faces the prevailing weather all make a difference to how aggressive the environment will be.
Beyond coastal environments there are situations where C&O regularly recommend Qualicoat Seaside. We recommend it for rail stations, transport hubs and industrial locations, where a combination of humidity, pollution and airborne contaminants create conditions that are harder on aluminium than a typical site.
In addition, we also regularly recommend Seaside for high-rise or difficult-to-access buildings where getting to the aluminium for inspection or maintenance is going to be costly and infrequent. In these cases, the additional cost of Seaside pre-treatment is offset compared to dealing with coating problems on a building you cannot easily reach in the future.
Working with C&O
The point we always make is if there is any doubt, ask our team for help. C&O have over 40 years’ experience in powder coating aluminium in challenging environments such as coastal areas so we can advise on the best pre-treatment process for your project so that you don’t have to deal with problems in the future.
For more information contact us.