Visual inspection of the surface revealed that the board is heavily corroded: brown rust and white rust (salts). A first water wash with 500 – 1000 bar pressure revealed new whitish white rust stains, with a rough irregular appearance to the touch. These were randomly formed on the entire surface of the digesters and could not be removed by simple pressure washing. Being an anti-ex area, it was not possible to use tools/equipment that produce sparks on impact, implying other mechanical cleaning methods, including brushing with wire brushes or grinding. Innovative solution: application of a brown and white rust neutralizing product, Eco cleaner (100% biodegradable product) with a thickness of 500 microns, left to act for a minimum of 12 hours. Removal of the resulting layer was achieved by additional washing with water at 500 – 1000 bar pressure.

Following the dismantling of the severely damaged plates, the phenomenon of “welding/bonding” between the metal plate, the screws and the supporting structure of the facade was observed. In some cases, part of the supporting structure was replaced, including portions with reduced thickness due to corrosion. The joining was carried out by means specific to the area. Heavily corroded, perforated or thinned metal plates were dismantled piece by piece, then new, custom-made metal plates were hand-made for replacement.