Been doing a lot of research of galvalume wondering if wetting or cleaning with hard water will make a difference with the blackening of galvalume roofing or if the people on here cleaning galvalume with no issues have hard water might be stupid but just curious
The ions that form protective scales on galvanized steel in water include magnesium and calcium cations (Mg2+ and Ca2+). The higher the level of these ions, the harder the water is considered. Moderately hard and hard water provide enough magnesium and calcium cations to form protective scales on the galvanized coating, which act as a barrier and provide corrosion protection to the underlying zinc and steel. Agitation of the water can remove these scales, which is why corrosion in the splash zone is particularly aggressive on galvanized steel. A common measure of water hardness is parts per million (ppm) or milligrams per liter (mg/L), which are equivalent measurements. Waters with hardness levels below 17 ppm are considered soft, while waters with hardness levels between 60-120 ppm are considered moderately hard, and that above 120 ppm are considered hard. The general trend for soft and hard waters is soft water is much more corrosive to galvanized steel than hard water because protective scales do not form on the galvanized coating in soft water.
