Organic Zinc Rich Coating
Definition - What does Organic Zinc Rich Coating mean?
Organic zinc rich coatings are anti-corrosive primers used to protect iron and steel surfaces. They contain a high percentage of zinc dust that acts sacrificially when in direct contact with iron or steel. The zinc dust provides cathodic protection to metal and is similar to cold galvanizing. The binder used in an organic zinc rich coating is often epoxy.
Organic zinc rich coatings are used by many industries to protect steel substrates from corrosion. They are used for industrial, automotive, and highway and infrastructure applications.
Corrosionpedia explains Organic Zinc Rich Coating
Organic zinc rich coatings provide cathodic protection, whereas regular paints protect by forming an impervious barrier between the metal surface and moisture in the atmosphere. When a cathodic cell is formed it protects the steel at the expense of the zinc. Here, zinc acts as a sacrificial source. In addition, the zinc primer provides some barrier protection to the surface.
Although zinc rich primers are sometimes used as a standalone coating, they are also often top coated with a paint or epoxy. These coatings provide a backup or additional method to protect steel from corrosion under a topcoat of epoxy or urethane paint by providing better adhesion properties.
Zinc rich coatings are available in two types:
- Inorganic zinc rich coating (IOZ coating) – These coatings must be applied by spraying. Without a top coat they provide better steel protection than non-top-coated organic zinc primers.
- Organic zinc rich coating – These coatings are normally applied by brush, roller or spray. Without a top coat they do not protect the steel as well as an IOZ coating.