Developed in 2003, this one page handout compares two guardrail applications to explain wet storage stain. Both guardrail sections were galvanized on the same day in the same batch. One developed a mild case of wet storage stain, while...
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Wet Storage Stain
Instructive about the minimization and treatment of wet storage stain, this publication prescribes surface treatments and remedial actions.
Wet storage stain is a white or gray powdery deposit that can develop on newly galvanized articles. It may be found on nested or stacked products where moisture gets trapped between the articles restricting adequate airflow to the zinc surfaces, or when galvanized steel is exposed to rain, dew, or high humidity conditions. Wet storage stain is the visible formation of zinc oxide and zinc hydroxide on the surface of the galvanized steel.
It is important to note the hot-dip galvanizing process does not contribute to the formation of wet storage stain. The stain occurs after the coating reacts with the environment, not during the coating process. The galvanizer is responsible for producing a high-quality galvanized coating in accordance with ASTM specifications and following best practices for avoiding wet storage stain on articles stored at the galvanizing facility. When those best practices are followed, the galvanizer is not responsible for wet storage stain developed at his facility, during transit, or storage at the job site prior to use.
Copies of this resource are available for purchase. Architects, engineers, and other specifiers in North America may request a single copy of any publication at no charge, unless otherwise indicated. Multiple copies require a $25.00 (US funds) minimum order, plus shipping and handling. Prepayment is required. (Member galvanizers are not eligible for complimentary printed copies and require a $75.00 minimum order.) Non-member galvanizers must contact the AGA directly at 720-361-4483.