Weathering steel is adversely affected by exposure to road salts. Corrosion rates are accelerated, and the design strength is lessened. • The chlorides in road salts make an aggressive attack on the zinc coating of hot-dip galvanized steel, but protection of the substrate steel from corrosion is still achievable.Weathering steel will develop a dark brown, rather consistent, patina over a three-to-five-year period. However, because the appearance often has an architecturally aesthetic purpose, it is necessary to blast or wire brush the surface in order to establish a uniform initial appearance. When in contact with concrete, the corrosion products of weathering steel bleed onto the concrete and create an unsightly stain. • HDG steel initially exhibits a bright silver-gray appearance and then progresses within six to 24 months to the matte gray look that lasts for decades. The corrosion of zinc is slow, and the corrosion products are virtually invisible to the naked eye.