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Perforated and Expanded Aluminium

What is perforated aluminium?

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.

What is expanded aluminium?

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.

Risk of filiform corrosion

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.

Protect your asset

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.


*Tropical projects – it is recommended to speak to a Dulux Account Manager or call the advice line for all tropical locations

Interior & exterior environments close to liquids other than coastal, river and lake salt water environments

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.

1Please note chemically treated water includes antimicrobial treatments, e.g. in pools, anti-corrosive chemicals, and soapy water in bathrooms and showers
■ Where indicated Alumi Shield warranties™ are available on areas >than 1m from the liquid (ie outside the splash zone)
  Where indicated Alumi Shield warranties™ are available on areas >than 2m from the liquid
◌ Where indicated Alumi Shield™ warranties are available on areas >1m from the liquid on interior applications and >2m on exterior applications
● Where indicated Alumi Shield warranties™ are available any distance from the liquid
Alumi Shield™ warranties are only available when applied by a Dulux Accredited Powder Coater to the warranty specification on recommended project types and conditions
All Dulux powder products are NOT suitable in strongly acidic or caustic environments so pH must be between 5 and 9.
Alumi Shield™ warranties are not available if the powder coating is immersed in any liquid.

For more information on Dulux Alumi Shield warranties visit here


Advice Line

Our dedicated consultants can help simplify the specification process, saving you time and money by providing the right coating advice for your project.
Call 0800 800 975

Worth doing, worth Dulux.®