The Colour Anodising Process
1The first step is the pre-treatment with cleaning and making the aluminium profiles ready. The profiles are etched in an alkaline bath for a certain period of time, a bath which is based on sodium hydroxide. Then the profiles are rinsed in order to remove any possible deposits. In connection with the pre-treatment special mechanical or chemical treatments may also be carried out.
2The actual anodising is the second step in the process. Here the profiles are immersed into an electrolyte bath, which is usually based on sulphuric acid. After anodising the microscopic pores in the anodising layer are still open.
The Colour Anodising Process (Ctd)
3The aluminium is now ready for colour anodising, which is the third step in the process. This step is optional. Colour anodising may be done either by immersing aluminium into an organic dye bath or by means of electro bronze. The latter is carried out by immersing the aluminium into a bath with a tin based solution and then applying a DC current.
4The fourth step in the colour anodising processs is sealing the surface. In order to obtain a fully protected surface the oxide layer must always be sealed. This is done by immersing the aluminium into a bath containing chemical sealant.
