Perforated aluminum is sheet aluminium that has been manually or mechanically stamped, punched or cut to create a pattern of holes, slots, or decorative shapes. The sheets are typically used on architectural residential and commercial developments and can provide acoustic dampening performance and energy savings through reductions in lighting and heating costs.
Expanded aluminium is a type of sheet metal which has been cut and stretched to form a regular pattern (often diamond-shaped) in a mesh-like form. In contemporary architecture, expanded aluminium has been used as an exposed facade or screen material which can be formed into simple or complex decorative shapes.
Filiform corrosion can develop where a coating is too thin, particularly around sharp edges that are common in perforated and expanded aluminium designs, leading first to cosmetic imperfections and ultimately to film failure and corrosion.
To prevent filiform corrosion it is essential that the sharp edges on the perforated and expanded aluminium are protected with a sufficient film build, particularly in environments where condition have a high corrosivity. As a result in high corrosive environments Dulux recommends an additional coat with Grey Primer/E-Prime, a epoxy powder primer, below recommended top coats.
Dulux recommend an Alumi Shield Warranty system for both interior and exterior usage on perforated and expanded aluminium. The use of an Grey Primer/E-prime powder primer is mandatory in conditions of high corrosivity below a recommended top coat. Although not mandatory, the use of Grey Primer/E-prime is also recommended in all other environments to ensure a sufficient film build is achieved. Where Grey Primer/E-prime is not used (as it is not mandatory) it is essential that the top coat film build be sufficient to meet minimum film build requirements and protect around sharp edges.
All Dulux Alumi Shield Warranties are available when applied by a Dulux Accredited Powder Coater to a approved specification.
Use the following table to help identify the product and system choice you have for the perforated or expanded aluminium on your project. Refer to the conditions information to determine the environment that your project will be exposed to.
Use the following table which references AS4312 and ISO12944 Atmospheric corrosivity zones in Australia to define the environmental conditions and product is suitable for.
For powder coated assets close to liquids other than the sea, eg fences near outdoor swimming pools, fountains, outdoor bathrooms or furniture etc please refer to the guidance below for your product options for your project.
For more information on Dulux Alumi Shield warranties visit here
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