The main reason for applying a zinc containing coating is to have a primer with the ability of providing cathodic protection. This will contribute to protecting the steel substrate and reducing the risk of having undercutting corrosion. For the cathodic protection process to work properly, it is extremely important that the coating contains a sufficient quantity of zinc metal in its formulation, usually above 75% weight of the dry film for waterborne and 82% for solvent borne paints.

The zinc epoxy shall be applied on steel blast cleaned to the standard Sa 2½ (ISO 8501-1). They offer very good airless spray application properties, are quickly recoatable, and show excellent compatibility with most coatings (except alkyd: saponification). It is a good primer for multicoat systems, both for new constructions as well as for field maintenance applications.

Zinc epoxy is often used as a holding primer both at industrial plants (during maintenance) and within shipping. It is quick drying and the overcoating interval is relatively short. It has very good adhesion, good impact resistance and is heat resistant up to approx. 120^oC. The abrasion resistance is good.
The disadvantages of zinc epoxy compared with inorganic zinc is first of all that the galvanic protection of the steel is limited as the electrical conductivity of the binder is low. Secondly, the acceptance level of chlorides on the substrate is lower. This is particularly a drawback for marine exposures.

• Good corrosion protection
• Good adhesion
• Good mechanical strength
• May be overcoated with all types of paint, except alkyds
• Chemically curing
• Short overcoating time

• Temperature dependent (5^oC)
• Two-component
• DFT: 25-90 microns (25-30 microns for underwater use)
• Dry heat resistant up to 120^oC
• Not acid and alkaline resistant (resistant at pH range 5-9)

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