What you should know about powder coating aluminium

Powder coating offers an unlimited selection of colors with varied gloss and with very good color consistency. It is by far the most widely used method of painting aluminium profiles. When does it make sense for you?

The Earth’s most abundant metal is renowned for its lightness, strength, and resistance to corrosion. Thanks to the excellent corrosion resistance of aluminium, surface treatment of the metal are rarely needed to improve its corrosion protection. And, for some at least, the silvery-white appearance of untreated aluminium extrusions is entirely adequate. But there are other reasons for treating the surfaces of extruded aluminium profiles. These include:

* Wear resistance

* UV resistance

* Supplement corrosion resistance

* Introduce Colour

* Surface texture

* Electrical insulation

* Ease of cleaning

* Treatment before bonding

* Gloss

* Retard wear and tear

* Add reflectivity

When specifying architectural aluminium, The most prominent surface treatment methods are anodizing, painting and powder coating. My focus today is powder coating.

Benefits of powder coating the surface of aluminium

Powder coatings can have a finish that is either organic or inorganic. This finish makes it less prone to chips and scratches, and long-lasting. It also contains chemicals less harmful to the environment than those in paint.

We call it the eco-friendly way of adding color.

One of the beautiful things about powder coating is that there are virtually no limits to the choice of color. Another benefit is that we have special antibacterial coatings for sterile environments, such as hospitals.

What we especially like about powder coating is its combination matrix of color, function, gloss and corrosion properties. It adds a layer to the aluminium that is decorative and protective, and it provides an extra layer of protection from corrosion, with thickness from approximately 20µm to as thick as 200 µm.

Cons of powder coating the surface of aluminium

• Filiform corrosion resembling threadlike filaments may form under the finish if incorrect pre-treatment methods are used.
• If the applied coating film is either too thick or thin or if the powder coating material is too reactive, ‘orange peel’ may occur.
• Chalking, which looks like white powder on the surface, may appear if the incorrect curing process is used.
• The very uniform and consistent coating make the replication of the timber aesthetic, if so desired, unconvincing.

Powder coating is a highly repeatable process

The powder coating process goes like this: After pre-treatments such as degreasing and rinsing, we use an electrostatic process to apply the powder coating. The negatively charged powder is then applied to the aluminium profile, which is positively charged. The subsequent electrostatic effect creates a temporary adhesion of the coating.

The profile is then heated in a curing oven so the coating melts and flows, forming a continuous liquid film. Once it is cured, a solid connection is formed between the coating and the aluminium.

An important point about the process is its high level of repeatability. You know what you are going to get.