First, an oxidation layer is formed using an electro-chemical process in a bath containing diluted sulphuric acid. The aluminium surface is converted into a layer of aluminium oxide with a thickness of 5 to 25 microns (one micron is one thousandth of a millimetre). As opposed to other surface treatments, anodising does not apply a layer to the aluminium, but instead a layer is created within the aluminium itself. An advantage of anodisation over a varnish finish is that it retains the beautiful metal-look of the aluminium.
The main purpose of anodising is to protect the aluminium against corrosion. A secondary benefit is that anodisation can enhance the look of the aluminium through pre-treatment and/or colouring.
It is possible to anodise using different layer thicknesses. We distinguish between 5, 10, 15, 20 and 25 microns. We recommend 15-20 microns for outdoor applications, 25 microns for extreme outdoor conditions (e.g. coastline or railways), and 5-10 microns for indoor applications.
The size of the bath determines the maximum product dimensions.
Bath size for natural anodising: 22,000 x 1,300 x 2,000 mm
Bath size for colour anodising: 7,600 x 350 x 1,500 mm