This week on the blog we are discussing the difference between two opposing aluminium surface treatments: anodising and powder coating.

Our mission in the blog is to take a closer look at options for aluminium surface treatment and provide you with all the information required to make an informed decision for your refurbishment or design project.

Despite aluminium being the world’s most abundant metal, renowned for its lightness, strength and resistance to corrosion, many choose to surface treat aluminium profiles and we’re going to give you the low down on the two preferred options available.

Here are five reasons why you might consider using a surface treatment for aluminium on your project:

  • to introduce colour
  • to supplement corrosion resistance
  • to augment hardness
  • to mitigate wear and tear
  • to add reflectivity.

So let’s consider your options. Anodising is a relatively straightforward electrochemical process, which has been around for 100 years, and is used to increase the thickness of the natural oxide layer surface of aluminium. Alternatively, powder coating is an electrostatic technique mainly used for decorative and protective finishes to aluminium.

Now let’s discuss the advantages and disadvantages of both.

 

Novartis Anodised Aluminium Design Woodform Architectural

Project: Novartis |  Photographer: Tyrone Brannigan | Architect: HDR Rice Daubney

Anodising

Pros:

  • Easy to maintain - periodic cleaning with water and a mild detergent will restore its original lustre.
  • The anodic coating will not peel or flake because it is actually part of the metal.
  • Anodising imparts a translucent metallic appearance because the base metal can be seen underneath the coating.
  • This method is unaffected by sunlight and mostly fade-resistant.
  • Anodised finishes are consistent regardless of the angle they are viewed from.
  • The end product does not emit volatile organic compounds (VOCs), nor are there any heavy metals involved in the process.

Cons:

  • The surface may become vulnerable to acidic pollutants in urban areas. 
  • The translucence of this coating contributes to colour variation issues between batches - although this lack of uniformity has been reduced in recent times.
  • Anodised finishes are normally only available in a matt and polished finish.
  • Since anodised finishes can only be applied to aluminium, other building elements in a similar colour may look conspicuously different.

Powder coating

Pros:

  • Dents and scuffs are easily repaired using liquid coating that accurately matches original colours.  
  • Powder-coated aluminium installed at the start of a project will look the same as other powder-coated battens installed towards the end of the project.
  • This finish is available in a huge range of colours (from simple matt, satin, and gloss finishes to super matt, super gloss, and textured finishes).
  • Powder coating has better chemical resistance to mortar, and to industrial-strength acidic and alkaline cleaners.
  • Powder coating has better colour uniformity between batches.
  • This finish does not produce air pollution.

Cons:

  • 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 makes the replication of the timber aesthetic, if so desired, unconvincing.

So there you have it: the low down on aluminium coating methods, and remember once you’ve made your choice always select a reputable supplier with a proven track record in quality assurance at every stage of production. We would recommend the following: Interpon and Dulux for powder coating and AAF for anodising.

All the best with your decision making, and if you require further information about aluminium products touch base with our expert team today at Woodform.

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