Decorative problem caused by waterlogging

Corrosion damage is not always due to errors in pre-treatment or coating. Sometimes constructive peculiarities coincide with particularly unfavourable environmental conditions.

On the windows of a row of shops near the North Sea, clearly visible white deposits kept appearing at the transition from the window to the frame. This made the shop less attractive. The owner initially suspected that it was the salty sea air crystallising in these areas. But the white spots kept reappearing, regardless of how often the windows were cleaned. Finally, Dr Herrmann GmbH & Co KG was commissioned to investigate the damage.

After dismantling a panel, it was discovered that the white deposits were to be found on the edge of the untreated aluminium brackets, in some cases on a large scale, and appeared to be literally blooming out from under the panels. Samples of the efflorescence were analysed in an expert laboratory in Dresden using metallographic cross-sectional examinations. The coating showed no defects. The cause was the cavities behind the panels, the capillary effect in combination with the climate.