Minimise the Effects of Weathering
Typical architectural powder coated fenestration
All materials when exposed to the elements will age in some form and change in appearance over time. Materials like stone and brickwork tend to age very well and offer an aesthetic look for many years with virtually no maintenance. Other materials such as copper take on a patina, a bright green colour in the case of copper, as the surface weathers and builds up a protective surface oxidisation. The effects of UV radiation and pollutants in rain can also have deleterious effect on many building materials often leading to premature failure. These finishes are often coated finishes and require careful specification.
First of all, it is important to consider the design of any facade or roof. It is important to consider run-off of rain, as, if allowed to concentrate in any area, this can lead to localised staining, even on brickwork. An example of a run-off detail is the use of drip cills under windows which allow rainwater to run off the facade rather than run down the facade.
Window and facade longevity starts with a high quality aluminium substrate pretreatment and powder coat finish as provided by a licensed QUALICOAT applicator. To identify a licensed QUALICOAT applicator in the UK or Ireland, simply go to the website www.qualicoatuki.org which is kept up to date with current licence holders.
Often overlooked in the specification process is the choice of pretreatment system on the aluminium substrate, this is crucial as it needs to completely seal the aluminium surface whilst offering a good key for the powder coating to adhere too. Despite the powder coating being of a consistent thickness, coatings are air permeable and as a result, if the pretreatment is poorly applied, oxidisation of the aluminium substrate over time could cause the finish to lift. UK and Ireland QUALICOAT applicators are routinely inspected by independent test house, IFO, to ensure that the latest QUALICOAT Standard is being adhered to which ensures that a robust pretreatment has been applied.
Prior to handover of any new installation or building, coated aluminium fenestration will be cleaned down professionally to ensure that the finish is not damaged. It is crucial at this time to have any areas of impact or abrasion damage repaired, should it be present. During cleaning, all the protective tape must be removed from the inside and outside of powder coated surfaces as if this is left on for an extensive time, the tape low-tack adhesive can often degrade, especially in UV light, and become firmly attached to the powder coating.
Once handed over to the client, in normal use such as in cities, the powder coat finish should simply be washed down at yearly intervals with clean water or with a ph neutral mild detergent solution in water. This should be enough to protect the visible surface of the powder coat for many years and can simply be done during the cleaning of windows. The powder coat finish wash down is especially important where squeegee bars are used to clean the glass, as their use tends to place the residue of the airborne contaminants directly on the powder coated frame which could begin to etch into the surface finish of the coating. Window cleaners must ensure that all powder coated surfaces are wiped clear of cleaning residue on every window clean.
The original colour of the powder coating can be affected over time by contaminants in the atmosphere and possible UV degradation. Ensuring that the regular cleaning cycles wash down and remove any atmospheric deposits, especially acids that can be present in precipitation, will certainly help reduce possible staining of the powder coating. Elevations in full sun could be affected by UV degradation where there may be evidence of chalking, which appears as a whitening of the surface. Chalking is caused by UV radiation which brings the binder in the powder coat to the surface and is not an indication that the powder coating has failed but is an indication that cleaning has been neglected. Again, regular cleaning cycles should keep any chalking to a minimum. Should a product or facade be allowed to fall into this state, there are specialist cleaning companies who may be able to clean and restore the coating to its original colour.
On all building projects, any powder coated finishes will come with a cleaning and maintenance regime from the company who coated the aluminium profiles, this may be an independent coater or a systems company. The cleaning regime will offer a minimum cleaning cycle which will need to be adhered to as well as being regularly recorded. This will ensure the coated finish is maintained within the applicators warranty and will help, should there be any claim in the future. Powder coat warranties vary in length and are dependent on 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 should be specified and the cleaning regime will often be increased to at least three monthly intervals as the atmosphere is much more corrosive.
Crucial to any maintenance regime is preventative maintenance and powder coating is no exception, if the coating has become damaged, exposing the aluminium, it should be repaired as soon as possible. For repair, either contact the original coater, or approach any QUALICOAT approved application who can normally offer guidance. If you have mislaid cleaning advice QUALICOAT UK & Ireland offer a basic guide which can be downloaded from their website.
The global QUALICOAT standard continues to be incrementally revised with update sheets and a reprint of the standard every year. The 2022 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.