Combining a paint system with hot-dip galvanised steel forms what is commonly known as a duplex system.

The hot-dip galvanised layer, made up of three layers of iron-zinc alloy and a layer of zinc, offers excellent protection against steel corrosion.

A paint system (liquid or powder) also protects the steel from corrosion. This is why the combined use of both systems offer such prolonged protection.

Prior to applying a powder or liquid paint system on the hot-dip galvanised steel, the layer of zinc must be made suitable for receiving a coating. By this we mean mechanical or chemical pre-treatment on the zinc’s surface, with a view to eliminating any extra thickness, drops and other imperfections that could create a fault in the paint system. Several finishing levels can be determined according to our customers’ specifications.

The Duplex system is standardised according to several standards, depending on the type of paint used (Powder coating or Lacquering)

EN ISO 15773 / 2009: Industrial application of powder organic coatings to hot dip galvanized or sherardised steel articles – Specifications, recommendations and guidelines.

EN ISO 13438 / 2013: Paints and varnishes – Powder organic coatings for hot dip galvanised or sherardised steel products for construction purposes.

Stages of the duplex process