Anodising is an electrolytic process to increase the thickness of the oxide layer that appears naturally on the surface of exposed aluminium.
In a nutshell:
- Anodising is an electrolytic process for aluminium that increases resistance to wear and corrosion
- It’s a popular coating for architectural façades and solar shading
- Anodising increases the extremely hard oxide layer - it does not chip or peel
- Light grey and bronze are common but many other colours can be achieved with dyes
- Anodising is typically more expensive than powder-coating but is longer-lasting, non-combustible and better-suited to corrosive environments
It increases resistance to wear and corrosion and is, therefore, a popular coating for architectural façades, rainscreen cladding and brise soleil systems.
Developed in the early 20th century, anodising is a simple process. The aluminium part is placed in a bath containing an electrolytic solution. An electric current is then passed through the bath, and a metal oxide film grows on the surface of the part.
The oxide layer is extremely hard, second only to diamond, and because it is formed by chemical reaction, it does not chip or peel. Anodising can be created in various thicknesses, but a thin layer will only be good for decorative purposes.
The natural anodised colour is silver or light grey, but a wide range of colours is possible. Adding metallic salts during the electrolytic process can produce the familiar bronze colour, but many other colours can be achieved with dyes.
Anodising is sometimes confused with powder-coating, but the process is quite different. Powder-coating uses a dry powder that is applied electrostatically and cured under heat or ultraviolet light. It creates a hard, protective layer that is tougher than conventional paint.
There are pros and cons with both types of coatings and although anodising is typically more expensive, it’s longer-lasting, non-combustible and better-suited to the corrosive salty environment of maritime locations.
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