ST PAUL, MN — 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 options when facing these elevated moisture problems.

VpCI®-396 is a very hard but flexible coating that cures in conditions of high humidity. It 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), making 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 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 can also be used 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 suitable 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.

Choosing the right coatings to go together 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 external corrosive elements. When tackling the challenges of high-moisture environments, finishers should select options that will best complement each other and the environment in which they are applied.

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