Maintaining the Colours of QUALICOAT
An automatic spray booth.
Powders today come in a rainbow of colours and can now be mixed to exactly match any colour, but, how can these colours be maintained to offer an extensive life expectancy?
Before we look at ongoing maintenance, it is crucial that any powder coating is applied to the very highest standard. Fortunately, the majority of systems companies in the UK and Europe coat their aluminium systems to the QUALICOAT Specification. This specification ensures the very best pretreatment of the aluminium prior to coating. Pretreatment of aluminium includes the removal of contaminants and oxidisation on the surface of the aluminium by an acid or alkaline etch. Removing the contaminants from the extrusion is part of the pretreatment process undertaken by either dipping or spraying an acid or alkaline solution which etches the surface removing a minimum of 1g/sm of aluminium. Leaving these contaminants on the aluminium has a detrimental effect on adhesion of the final coating.
After cleaning the surface of the aluminium the surface is pretreated with a passivation coating that both seals the surface of the aluminium and offers a key for the powder coating to adhere to. Pretreatments currently include chrome and non-chrome based systems and pre-anodising. The choice depends on the location of the installation, guidance of these exposure categories can be found on the UK & Ireland Association website.
Most domestic installations in the UK, away from the coast will offer many years life expectancy with a standard supplied powder coating, once properly maintained,. To ensure coating sustainability, it is important that ‘Seaside Class’ is specified for installations that are within 5km of the coast or tidal estuary. Your systems supplier or powder coater can advise in more detail.
Introduced in 2008, QUALICOAT began to offer a ‘Seaside Class’ of powder coating where the minimum removal of aluminium surface is increased to 2g/sm using a dip or spray process of either an acid or a combination acid/alkaline etch. This deeper etch removes more contaminants and therefore offers a more robust pretreatment for areas where local atmospheres carry corrosive salts (chlorides) and other aggressive pollutants. QUALICOAT licensed applicators who wish to offer ‘Seaside’ class coatings need to apply for an additional licence. The applicator needs to demonstrate that they can remove the 2g/sm by process and monitoring, plus the applicator must offer a coated ‘Seaside Class’ sample for an additional filiform corrosion test carried out at the IFO laboratories located in Germany. IFO provide independent inspection and testing services for all QUALICOAT powder coat applicators in the UK.
Once handed over to the client, in normal use such as in towns and cities, the powder coat finish should simply be washed down every few months 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.
QUALICOAT UK & Ireland have a free to download ‘Recommendations for the care of coated aluminium’ brochure available on their website and it is advisable to hand this over to the client on completion of the installation.
The up-to-date QUALICOAT Specification is freely available for download via the UK & Ireland Association website, qualicoatuki.org and the website offers an up-to-date list of licensed UK and Ireland Powder Suppliers, Pretreatment Suppliers and Applicators including the applicators who carry the Seaside class accreditation. Telephone support is available from QUALICOAT UK & Ireland Head Office in the Midlands on 0330 240 9735, the Association can also be followed on Twitter @Qualicoatuki or on LinkedIn www.linkedin.com/company/qualicoat-uk-&-ireland.