Anodising is an electro-chemical process that builds up a protective layer on the surface of aluminium profiles. The metallic finish that is created does not peel, chip or flake and achieves good protection against sunlight, atmospheric corrosion, heat and moisture.
Anodic treatment can accentuate the effect of any lack of homogeneity or differences in metallurgical condition of the aluminium. This means that some non-uniformity of appearance may be encountered on different areas of the component and/or different batches of material to the same specification, or where certain processes have been used.
It is sometimes possible to observe, on close inspection or from certain viewing angles, variations in brightness, banding, streaming and other visual effects on the significant surfaces. These seldom impair the performance of the anodised aluminium and, as such, should not be grounds for rejecting the product on a performance basis.
The provision of agreed samples is a useful guide in production and it should be recognised that they are of limited value in assessing final appearance, since different forms and sizes of material may respond to processing in slightly different ways.
It is important that a viewing distance of not less than 2 metres is required when viewing external architectural applications. Anodised finishes are preferably matched in daylight, but not direct sunlight.