Zinc coating is the most commonly used material to increase the corrosion resistance of steel. The zinc protects iron by corroding first. In the event the underlying metal becomes exposed, protection can continue as long as there is zinc close enough to be electrically coupled. After all of the zinc in the immediate area is consumed, localized corrosion of the base metal can occur.
The continuous galvanizing process is specified according to ASTM A653, which designates specific zinc coating weights, indicated by a “G” (galvanized) followed by a number. The number represents the total weight of the coating. For example, G235 steel has 2.35 oz/ft2 total coating (1.175 oz/ft2 on each side).