Hot-dip galvanized (HDG) steel is specified because it provides maintenance-free corrosion protection for decades. However, some architects and engineers under utilize HDG because of concerns about its appearance. Due to steel chemistry, fabrication processes, and other factors, the initial appearance of hot-dip galvanized steel can vary from bright and shiny to matte gray, or a mixture of both. Many specifiers erroneously equate the appearance of the coating with coating quality. It is important to note the durability of galvanized coatings is not determined by the appearance, but rather by the zinc coating thickness. Regardless of the external appearance of the coating initially, all galvanized pieces will protect steel from corrosion for decades. Additionally, as the galvanized steel weathers, initial variances in appearance will fade, producing a uniform matte gray coating.

This one-page publication discusses the appearance and weathering of hot-dip galvanized steel and how they relate to the durability of the galvanized coating. Using a case study example, this handout shows how differences in appearance do not affect coating performance and how the variations even out over time as the coating weathers.