Duplex systems, or painting over hot-dip galvanized steel, have been used for decades as a means to enhance corrosion protection. Painting over hot-dip galvanized steel provides the owner/specifier with effective corrosion protection, while still allowing the structure to be painted for color or aesthetic reasons. Duplex systems are becoming increasingly common and popular because of this combination of benefits.

Successfully painting over hot-dip galvanized steel is relatively simple. Just like painting on any other surface, proper surface preparation is key to creating an effective bond between the paint and the galvanized surface. Galvanized steel requires slightly different preparation steps according to the surface condition. Thus, proper preparation relies on correctly identifying the galvanized surface condition, and then following the appropriate cleaning and profiling steps to achieve optimum bonding of the paint to the hot-dip galvanized steel. For detailed instruction on preparing the surface, refer to ASTM D6386: Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Painting.

Revised in 2009, this package includes an instructional guide booklet and step-by-step CD on how to prepare the hot-dip galvanized steel surface for paint.