This is a specialist process which is used in applications where both high corrosion resistance and areas of electrical conductivity are required on the same component. Dual finishing or selective anodising which it is also called is available for a combination of sulphuric anodising and chromate conversion as well as hard anodising and chromate conversion. The process involves high precision masking of areas which are to be free of anodising, these may be specific holes, earthing points or areas of maximum tolerance sensitivity.