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Architect: Allies & Morrison
Location: Sheffield
ANODISED ALUMINIUM PAINTED PANELS
The big attraction of anodised aluminium is that it is highly durable and rust-free, but it has one hitch - it doesn't lend itself to being painted. And as the architect wanted to paint the internal face of the triangular panels green to make the interior more inviting, the question was how would it achieve this.
Anodising the aluminium is an electrochemical process which increases the thickness of the natural oxide layer on the metal's surface. The oxide film is grown by immersing the aluminium in a bath of weak sulphuric acid and passing a current of about 150 amps per sq m between the aluminium, which act as the anode, and the cathode.
In the final stage of the process, controlled hydration using boiling water seals the pores and establishes the corrosion resistance of the film. The finished material is porous, hard, transparent and extremely durable.
Applying powdercoated paint to this surface was attempted, but sealing the paint onto the surface required baking it at very high temperatures, which led to cracking in the aluminium. The answer was to find a company that could strip one side of the anodised aluminium panel and paint it, and McMullen Architectural Systems fitted the bill.
The architect specified a paint commonly used for boats which is particularly durable. The paint finish is an acrylic two-pack (2K) paint, mixed to match Dulux colour reference 90YY 55/560 Green.
Before the paint was applied to the panel, the anodised surface was treated with a primer on the internal side....