Zinc Rich Coating

Definition - What does Zinc Rich Coating mean?

A zinc rich coating is a coating that contains a high percentage of zinc dust and acts sacrificially when in direct contact with steel. Zinc rich coatings are applied to protect steel surfaces from corrosion and extend the surface's life. Zinc rich coatings provide cathodic protection to metals similar to cold galvanizing.

Zinc rich coatings are used by many industries to protect steel substrates from corrosion. They are used in highways and infrastructure, industrial and automotive applications.

Corrosionpedia explains Zinc Rich Coating

Zinc rich coatings provide cathodic protection, whereas regular paints protect by forming an impermeable barrier between the metal and atmospheric moisture. The cathodic cell protects the steel at the expense of the zinc. Zinc coatings also provide some barrier protection to the surface.

Although a zinc rich coating can be used as a standalone coating, it is often top coated with a paint or epoxy. This primer provides a backup or additional method to protect the steel from corrosion under a top coat of epoxy or urethane paint.

There are two types of zinc coatings:

  • Inorganic: Inorganic zinc coatings must be applied by spraying. Inorganic zinc coatings provide better steel protection than non-top-coated organic zinc coatings when not using a top coat.
  • Organic: Organic zinc coatings are normally applied by brush, roller or spray. When not using a top coat they do not protect the steel as well as an inorganic primer. Organic zinc coatings do provide the same degree of protection as inorganic coatings when the coating is top coated. Organic zinc coatings can be a moisture-cured urethane zinc primer, which is easy to apply to a surface.

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