Corrosion Benefits of Zinc Plated (Galvanized) Steel
The vast majority of SCAFCO products are produced with zinc-coated steel. The zinc coating is produced through a process of hot-dip galvanizing, where unprotected steel is immersed in a bath of molten zinc. This process produces a thin layer of zinc on the steel surface. The hot-dipping process produces steel where the zinc is molecularly bonded to its surface. This process strengthens corrosion resistance in two ways.

First, the zinc coating encapsulates the base steel. This prevents oxygen and water from interacting with the base steel. The zinc sacrifices itself, preventing the steel from losing structural integrity in the presence of a corrosive environment.

Second, and often more importantly,the bonding of the zinc and steel produces. a small electrical current called galvanic action. Galvanic action protects the base metal (in this case, the steel), even when it is exposed to the environment. When galvanized steel is damaged, either by scratching, or in the case of sheet steel, shearing, the base steel is exposed to the environment. During shearing , a thin layer of zinc will drag down the face of the cut by the shear. Initially, if the base steel is exposed, a small layer of red rust (Fe2O3) may form. However, as time passes, galvanic action takes place. The surface layer of zinc will sacrifice itself to prevent the base steel from corroding further. Over time, the red rust will turn from the bright red color to a dark black surface, signifying that the base steel is no longer being corroded.. At this point, no further deterioration of the base steel will occur. The same process occurs in the case of hot-rolled steel as well.

Occasionally, red rust stains are seen on galvanized steel surfaces, like silo roofs. This likely is not the corrosion of the base metal, but is simply a rust stain from untreated carbon steel overhead. The rust from the untreated steel drips onto galvanized surfaces below. This is a surface stain and is not the corrosion of the base metal under the zinc coating. The stain may be removed by a light scrubbing with an Oakite or vinegar solution. The overhead untreated steel should then be painted or treated to prevent future rusting.