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Steps to Successful Duplex Systems

Communication between the fabricator, specifier, painter, and galvanizer is vital before galvanizing. The various parties may desire special handling or require alterations to the design to facilitate the galvanizing process and/or the application of paint. Furthermore, if the galvanizer is aware the part will be painted after galvanizing; precautions can be taken to avoid any processes that may interfere with the adhesion of the paint system.

Many galvanizing facilities either immerse the part in a water-quench or passivation bath to cool the parts to facilitate quick handling as well as prevent the formation of wet storage stain. The passivation prevents the formation of excessive zinc compounds, but also interferes with paint adhesion and can lead to paint peeling.

The following table provides a look into the steps for successfully painting or powder coating over hot-dip galvanized steel:

Paint Over HDG Powder Coat Over HDG 
Communicate with galvanizer/painter Communicate with galvanizer/painter
Identify the surface condition Identify the surface condition
Smooth, clean the surface  Smooth, clean the surface 
Profile the surface  Profile the surface 
Paint Bake
  Powder coat
  Cure the coating