E0 pickle
It removes the existing oxide layer and some of the aluminium layer thickness. The existing surface finish is retained. Scoring, scratches, chafe marks, etc. remain visible. Corrosion phenomena that were not or only with difficulty visible before pickling can be made visible by this pickling process. The surface has a shinier metallic effect than an E6 stained surface.
E6 pickle
It removes the existing natural, even oxide layer and at the same time creates a matt surface. Slight scratches and chafing can be levelled but not completely removed, so that deep grooves, scratches, chafing, stronger partial corrosion layers etc. remain visible. Corrosion phenomena that were not or only with difficulty visible before pickling can be made visible by this pickling process. Irregularities in the microstructure, e.g. bar drawings, coarse grain formation, alloy deviations are highlighted in particular