Perspective on "Atmospheric Corrosion Resistance of Skyward- and Groundward-Exposed Surfaces of Zinc- and 55% Al-Zn Alloy-Coated Steel Sheet,"HE Townsend, Corrosion 54, 7 (1998): p.561-565

Twenty-year exposure testing of sheet steel panels with hot-dipped coatings of zinc and 55% Al-Zn alloy at rural, industrial, and marine sites was performed with specimens designed to allow independent assessment of the skyward and groundward facing surfaces. The results revealed that the groundward facing surfaces corroded at lower rates than the skyward facing surfaces, although the groundward facing surfaces showed accelerating rates throughout the exposure. This effect was probably caused by the chromate conversion coatings on these specimens.