Often sheet aluminium is used for cladding purposes. It is frequently treated to give a self-coloured coating. Anodising is a typical example. Ready-painted forms are available with long-life and textured coatings which are ideal for exterior cladding.
Polished aluminium sheet is often produced with special pre-treatments to enhance the adhesion of surface coatings. If a factory treatment is not available manual/mechanical abrasive methods must be used.
Cast aluminium provides a rough surface and does not require a pre-treatment prior to the application of the appropriate system primer.