There are two main challenges facing protective coatings in high moisture conditions. One is the issue of durability in a moisture laden or immersion environment that is naturally more corrosive than a dry environment. Another issue is the challenge of being able to properly cure a coating in the presence of moisture. Cortec’s Micro-Corrosion Inhibiting Coatings™ provide an excellent palette of coatings options when facing these elevated moisture problems.
Micro-Corrosion Inhibiting Coatings™ palette
VpCI®-396 is a great place to start when looking for a very hard but flexible coating that cures in high humidity conditions. VpCI®-396 is a solvent-based moisture cure urethane that can be used as a direct-to-metal (DTM) primer, and in some cases a topcoat. It provides protection in harsh, outdoor, unsheltered applications and cures best when applied under relative humidity of 20% – 80% with temperatures ranging from 32-120 °F (0-50 °C). This makes it a good option for ballast tanks or structural steel and tanks in a chemical- or water-vapor rich industrial environment.
VpCI®-396 can be used over CorrVerter® Rust Converter Primer on previously rusted surfaces. CorrVerter® is a fast-drying water-based one-coat system that converts these rusted surfaces to a hydrophobic passive layer and prevents further rusting through the unique formulation of chelating agents and PVDC resins. It offers excellent 5B adhesion and eliminates the need for blasting in situations where this is not convenient or allowed.
A coatings system of CorrVerter® top-coated with VpCI®-396 is suitable for immersed structures such as storage tanks or even holding tanks containing hydrocarbons or high salinity solutions. This coatings combination is also excellent for application over rusty surfaces on wind tower base bolts, electrical poles, and other outdoor structures in high humidity environments.
VpCI®-395 is a Water Based Epoxy Primer that is good for immersion applications on rust-free surfaces. It is a fast drying, two-component system that can be applied DTM and also provides protection in harsh, outdoor, or unsheltered applications. VpCI®-395 should be coated with a urethane such as VpCI®-396 for enhanced durability.
Selecting a winning coatings combination
Choosing the right coatings to go with each other can be as important as selecting a good coating to begin with. A good primer provides an important baseline for successful coatings performance, good adhesion, and a better finish; while the right topcoat completes the system to provide extra resistance to the corrosive elements externally.