Zinc rich primers provide the first line of defense in the fight against corrosion. Zinc epoxies compared to zinc silicates as coating solutions, are more flexible regarding curing conditions, they are easier to overcoat and they are less demanding to substrate preparation prior to application.
A new generation of activated zinc rich primers with enhanced corrosion and mechanical properties has been successfully introduced in the market since 2014. This new technology delivers an efficient galvanic protection while providing a more effective barrier and inhibition effects to the coating system.
The purpose of this paper is to present real life and accelerated performance testing that provides additional data that go beyond standard performance in the market. A Life Cycle analysis will be presented as well demonstrating that solutions based on activated zinc have the best sustainability profile, based on outstanding performance and longer durability.
Zinc rich primers, both organic and in-organic coatings, are extensively used in the marine and offshore industry. The beneficial effect of zinc-rich primer on the longevity of protective coatings is primarily assumed to be due to a cathodic protection mechanism. During the 60's and the 70's zinc rich epoxy primers dominated the market. Later, zinc ethyl silicate primers took over this role but nowadays it looks as if zinc epoxy primers have made a comeback[1].
Some of the advantages of zinc epoxies compared to zinc silicates are the less demanding curing conditions (epoxies will cure faster and they do not require moisture to cure), they are easier to overcoat (the porosity of silicates may cause popping), they are less demanding to substrate preparation prior to application and they have lower VOC content. Furthermore, zinc silicates will have a tendency, to mud cracking even at moderate film thickness[2]. This makes the zinc epoxy primers very attractive for maintenance use and for new building where surface preparation and application requirements cannot be met, applicators are less skilled and/or where climate control during application does not favor zinc silicates[3].
The increasing demands to the performance of zinc rich primers (low rust creep) has generated even more focus on maximizing the utilization of the zinc dust in the paint and optimizing the rust creep resistance[4].
A new generation of activated zinc-rich primers, with improved corrosion and mechanical properties, without increasing the zinc content, are available for the last 7 years.
