Manufacturing with Coated Products
Members of QUALICOAT, from the pretreatment systems providers, the powder systems providers and applicators, all work very closely together under the 2021 edition of the QUALICOAT Standard to ensure that architectural powder coating meets the highest standards for todays use in architectural applications. In order for the finished aluminium profiles to be made into windows, doors, roof lights and curtain walls, the material that is shipped to the fabricator needs to be carefully cut and manufactured into products ready for site installation. Great care is needed to ensure that the final product maintains its high quality finish.
Low-tack protection tape is required to be placed on the final visible faces of the profile to protect the powder coating through the manufacturing process and is then often left on the product when installed on site, which offers ongoing protection. The supply and application of tape can be completed at the powder coat applicators premises or fabricators premises, often with the systems supplier or installers branded tape.
Cutting the profiles into their assembly lengths, with either mitred ends or square cut ends, depending on the product, needs to be completed to a high standard with precision machinery to ensure that the final joint becomes watertight once constructed. More importantly is that a clean sharp cut gives a clean edge to the coating with less chance of the powder finish itself becoming stressed. If on cutting there are signs of chips revealing the aluminium surface, this could be a sign of poor powder coating adhesion and something the fabricator should take up with their powder coating supplier. It is crucial that architectural aluminium profiles are subject to an extensive pretreatment process, both equipment and processes are tightly controlled in the QUALICOAT standard.
Prior to joining profiles, the tape should be cut back slightly and removed to reveal the joint surface, this especially important where mitre joints are to be made. Aluminium mitred corners are held together with substantial aluminium extruded or cast cleats and sometimes with the addition of stainless steel chevrons. It is imperative that the system manufacturers parts are used together with the correct two part epoxy adhesive specified in their construction manual. Care is needed to ensure that mating faces of the aluminium profile are ‘buttered’ with the adhesive prior to final assembly and crimping of the joint.
It is critical to clean the final joint as soon as possible, as any adhesive left on the coated surface can damage the powder coat finish, or set and become impossible to remove. Sadly all too often products can be seen where adhesive has been spread across the mitre, seemly cleaned off and then only becoming visible as a damaged finish once the protective tape has been removed on site.
A joint which is not glued, or has not been mitred accurately, allows surface contaminants left by the weather to enter the joint and begin to oxidise the cut ends of the aluminium, this is further exacerbated by window cleaning. As most window systems are internally drained, the unsealed mitre also allows drainage from the system through the joint which often leads to staining of the surface finish.
On the rare occurrence of powder coat failure, the fault can often be put down to an inadequate pretreatment process, this is an issue that all QUALICOAT members are aware of and as a result all members pretreatment processes are openly and regularly third-party inspected within the QUALICOAT Association in order to maintain their coating licence.
Finally, the product fitted on-site is then offered a clean down and any protection tape on the inside and outside of the windows can be removed. It needs to be stressed that removal of the protection tape should be undertaken as soon as site conditions permit to reduce the possibility of blanching, as Low-tack protection tape does dry out over time due to weathering and UV light. Tape, if left on for long periods of time, can become very difficult to remove requiring specialist cleaning and in the worst cases the need to replace installed products.
Virtually all aluminium systems companies in the UK now offer QUALICOAT approved finishes as standard and it is unusual to see any significant project in the UK that does not carry the QUALICOAT specification for its architectural powder coating. A well specified coated aluminium system can easily last the lifetime of a building given minimal but regular maintenance.
The Association website, www.qualicoatuki.org offers an up-to-date list of licensed UK and Ireland Powder Suppliers, Pretreatment Suppliers and Applicators. Printed literature and telephone support is available from QUALICOAT UK & Ireland Head Office in Birmingham on 0330 236 2800 or email email@example.com. The Association can also be followed on Twitter @Qualicoatuki
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