Powder perfection

John Park-Davies, Group Marketing Director of Vertik-Al, explains the process and benefits of powder coating architectural aluminium and explores the myriad of colours and finishes available and how architects are using them to differentiate buildings, create drama and act as an alternative to high-impact glazing.

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Over the past 18 months, we have witnessed a step-change in architectural design. Where once glazing was the default facade of choice, we’re seeing architects and designers move away from glass and seek alternative materials and finishes.

Last year, architecture, interiors and design magazine ‘Dezeen’ featured an article which sums up our feel for the global facade market – “Architects in New York are returning to stone and other solid-looking materials to cover their towers, after years of glass dominating skyscraper construction in the city.

“SHoP Architects’ Gregg Pasquarelli…believes that glazing has become too obvious as a choice for architects and developers, and that it is quickly going out of style.

“Pasquarelli told Dezeen: ‘While some are spectacular, many glass facades have become a default design solution, usually when the client or the architect is out of ideas.’”

Yes, it’s a bold statement and unsurprising from a design principal responsible for a pair of copper-clad skyscrapers but, Pasquarelli has a point. We have recently powder coated over 35,000Lm of aluminium bar in metallic gold. These profiles were then fabricated to form a series of unitised panels that were destined for blocks of high-rise apartments in a city-centre riverside location.

We have also seen a marked rise in mixed textured finishes, for example, we have completed a vast powder-coated commission in contrasting matt, gloss and ‘Portland stone’ finish. The project comprised hundreds of unitised panels for a city-centre development, totalling over 25,000m2 white and brown stone-effect and 40,000m2 RAL 7024 Matt, RAL 9011 Gloss and RAL 8014 Matt.

So, with architects, designers and clients looking for something different to the vast swathes of glazed facade of the noughties, it’s worth exploring the alternatives, not least aluminium.

Aluminium is one of the most durable and sustainable building materials available, and the market is growing, steadily. Figures from the Council for Aluminium in Building (CAB) support this. The latest Q1, 2019 CAB State of Market Survey (released in June) showed “…continued rises in expected sales volumes and a very positive view of capital investment over the next 12 months”.

With such a resistant aluminium market, it’s important that architects, designers and specifiers appreciate the coatings and finishes available, the two most popular being powder coating and anodising.

In a statement, Russell Deane, Global Architectural Manager at AkzoNobel Powder Coatings, said: “Understanding the differences and relative advantages of powder coating and anodising is extremely useful. A weak specification, or a wrong choice of coating, can have a disastrous effect on the colour of the building [product] in the long term. And colour is just one of the key considerations.”

What is powder coating?

Powder coating is, as the name suggests, a type of coating that is applied as a solid powder rather than the liquid of more conventional coatings. The omission of any liquid solvents and their ability to be infinitely recycled during the application process results in an exceptionally eco-friendly final coating with no volatile organic compound (VOC) issues and minimal waste when compared to liquid coatings.

The powder-coated film is very tough and resilient, and dependent on the resin chemistry utilised, can offer coatings with exceptional chemical resistance, durability and a spectrum of aesthetically pleasing colours and surface finishes.

How does it work?

Powder coatings are manufactured from a mixture of resins, hardeners, pigments and additives that are extruded together and then ground into a fine powder. They are normally factory applied to metal substrates (non-heat-sensitive) via an electrostatic application method.

The three-stage process involves:

1. Metal components must be suitably cleaned prior to coating to ensure the removal of dust, oxides and grease. Depending on the final application, further surface treatment may be required to improve; for example, corrosion resistance and mechanical adhesion of the powder paint.

2. The powder is fluidised in air and passes through a corona discharge, the components to be coated are earthed so that the charged powder particles are attracted and electrostatically adhere to the component’s surface.

3. The component is then placed in a curing oven. During the curing process, the powder paint melts to form a continuous liquid film. Upon continued heating, a chemical reaction occurs between the resin and curing agents that results in a hard, thermoset coating.

Quality of finish

Consistency and quality of finish are essential for the coating to have an impact. Look for companies that are committed to quality and carry relevant and respected certification such as BSI approval, Qualicoat quality label and GSB International licence. All require stringent controls, checks, and often, random audits; giving peace of mind and reassurance to architects, specifiers and building owners/management companies.

Aluminium and its kaleidoscope of finishes is a worthy alternative to glass. Just think, by working with global powder companies – including AkzoNobel, Synthapulvin, Axalta, IGP etc. – we generally use around 400 colours regularly, but there are over 3500 at our disposal, and when one adds the vast selection of textures, the world has tens of thousands of finishes to choose from.

The possibilities of powder coating are infinite. Isn’t it time you discovered the power of powder coating?

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