Duplex Systems

A duplex system is the combination of two protective coating systems: a hot-dip galvanized coating followed by a topcoat of paint or powder coating. When used together, duplex systems provide a life expectancy that’s approximately 1.5 to 2.3 times greater than either protection method applied independently.


The key to a successful duplex system is to properly prepare the galvanized surface according to ASTM D6386 and ASTM D7803. While hot-dip galvanizing offers both barrier and cathodic protection, the topcoat in a duplex system provides an additional defense that significantly extends the life of the structure. The synergistic effect can be summarized as follows:

  • The topcoat provides a surplus barrier that slows down the rate at which the zinc is absorbed into the atmosphere.
  • The galvanized coating acts as a primer, eliminating areas of spotted corrosion.
  • The zinc beneath doesn’t begin to corrode until the topcoat has been weathered down or damaged.


  • High Performance & Sustainability: With enhanced corrosion protection, duplex systems are suitable for the most aggressive environments.
  • Cost Savings: Duplex systems extend the life of your structure and have a delayed maintenance cycle, resulting in substantial cost savings over time.
  • Aesthetics: Painting and powder coating provide an aesthetic alternative to the metallic finish of galvanized steel.
  • Safety: Duplex systems increase safety, enabling colour-coding systems that can identify such things as hazardous work areas, high voltage electrical lines and the colour coding of steam, gas or chemical pipes.
  • Easy Retouch: Quick touch-ups to the paint or powder coating can be easily and inexpensively executed.

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If you can have questions regarding pricing, please contact Daam Galvanizing and we will be happy to assist you.