Standardised metal samples are therefore exposed at every site in the network, for example samples of weathering steel or titanium zinc, one of the most important roofing materials. «Titanzink ist auf dem Bau beliebt, weil es komplett recyclebar ist. Für den Gebäudeerhalt macht es dabei einen erheblichen Unterschied, ob das Metalldach und die Dachrinnen nach 40 oder erst nach 80 Jahren ersetzt werden müssen» [English translation: “Titanium zinc is popular in construction because it is completely recyclable. For building preservation, it makes a considerable difference whether the metal roof and gutters have to be replaced after 40 or only after 80 years.”], says Hans. The Swiss site on Chaumont, the local mountain of the city of Neuchâtel, is virtually the model example within the “ICP Materials” network: the “exposed” samples corrode practically without harmful environmental influences, but solely because of the purely natural redox reaction of metal, water and oxygen. At the other end of the scale, when measurements began, were industrial sites such as Bottrop in Germany and Kopisty in the Czech Republic. In Kopisty, corrosion researchers were able to scrape half a kilogram of rust from one square metre of steel in 1987. Today, however, conditions are better at all sites. In industrial areas, between 100 and 150 grams of steel per square metre are lost each year. On Chaumont, only 30 grams of steel rust away over the same period.