Why plastic snow guards instead of metal snow guards?
The plastic snow guard came about in 1976, when the late Jack McMullen was receiving negative feedback on metal snow guards in his own metal building business. In addition to getting brittle and breaking in the cold, some of the metal guards were causing severe dissimilar metal reactions that ended up eroding the metal panel finish. In these cases the conductive liquid or electrolyte was rainwater. During evaporation water becomes concentrated and water films become more conductive, causing the initially benign water to create a dynamic galvanic effect which causes rust. This phenomenon normally begins to occur when water gets trapped in a crevice, such as under a screw or between the base of a metal guard and the metal roof. Even water lying against the face of the metal guard and the metal roof for an extended period time can initiate the deterioration process. Painting the metal guards did not prove to be a reliable solution but it did slow the galvanic reaction process down somewha
