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Powder coating vs Anodizing

Two coating systems are used to protect the surface of aluminum profiles - anodizing and powder coating. These two are the most widely used types of coating for architectural aluminum. They improve the corrosion resistance, provide the desired color, improve surface quality and reduce wear and tear.

Anodizing is an electrochemical process that increases the size of the natural oxide layer on the surface of the metal. On the other hand, powder coating is a technique that provides both protective and decorative finishes to profiles. During powder coating, an electrostatically charged mixture of colored powder and milled resin is sprayed onto the surface of the aluminum profiles. Then the coating is smoothened in a curing oven.

Pros of Powder Coating

Powder coating is a versatile surface treatment that offers many distinct benefits.
* Powder-coated aluminum has consistent color and it is uniform between each batch of profiles.
* The powder-coated aluminum installed at the beginning of the construction project will be the same as those installed at the end.
* Powder coating offers better resistance to acidic and alkaline cleaners.
* Liquid coating can be used to repair any dents or scuffs that occur on a powder-coated surface.
* Powder coatings do not release any volatile organic compounds (VOCs) and so they are more environmentally friendly.
* Powder coating can be used to produce a variety of surface finishes including matt, gloss and textured finishes.

Cons of Powder Coating Aluminum

As good as powder coating is, it has a few drawbacks including:
* When improper pre-treatment techniques are used, filiform corrosion may form underneath the finish.
* When the coating is too thick or too thin, it may peel off from the surface of the profile. This is usually known as orange peel.
* If the curing process that is meant to smoothen the coating is not effective, it may cause chalking. Chalking creates a white powder like substance on the surface.

Pros of Anodizing
* Anodizing creates a translucent metallic appearance and the base metal can be seen under it.
* Anodizing does not fade in presence of sunlight.
* Anodized aluminum profiles are easy to maintain. They can be cleaned with water and a mild detergent.
* Anodizing does not emit any volatile organic compounds and it does not cause any form of air pollution.
* The coating made by anodizing does not peel off because it is an integral part of the metal.

Cons of Anodizing
* Anodized finishes are only available in polished and matt finish, you can't get a gloss finish with anodizing.
* The surface of the anodized metal is porous so it may be attacked by acidic pollutants.
* Color variation can occur due to the translucent nature of the anodized surface.
* Other building elements may look different from the anodized metal because the anodized effect can only be applied to aluminum.

Obviously, powder coating has some distinct advantages over anodizing because of the consistent color finish but it costs more. So when there is no need for a colored surface, and the environment does not contain salt or acidic elements, anodizing may suffice.