E0 - Etching
When anodizing for technical or functional purposes, the aluminum surface is cleaned, degreased and lightly etched. There is hardly any aluminum removed and damages to the surface such as scratches remain visible. In the area of architecture, this pre-treatment is well suited for invisible substructures.
E6 - Etching
When anodizing for decorative purposes, the process cleans, degreases, chemically matts and etches the aluminum surface. It removes aluminum, alloying elements and slight damages to the surface in order to provide and create a homogeneous aluminum surface for the subsequent anodization. It should be noted that not every aluminum alloy is suitable for decorative anodizing.