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The RUST-OLEUM 278269 is the base component of Topside Vapor Barrier, a 100% solids two-component epoxy primer designed for concrete floors with elevated moisture conditions. It provides tenacious adhesion to damp and moisture-laden slabs, holding back up to 25 pounds of moisture vapor transmission per 1,000 square feet per 24 hours. The product is unaffected by pH levels up to 14, making it suitable for highly alkaline concrete conditions. Licensed flooring contractors and commercial floor coating installers apply this product as a primer layer before finish coatings or floor coverings. The base component ships in a 3-gallon quantity within a 5-gallon pail and requires Activator 277500 for activation.
This epoxy primer is used on concrete floors in both residential and commercial settings where high moisture vapor emission rates would otherwise compromise finish coat adhesion or cause flooring failures. It functions as a primer within solid color systems, broadcast resinous flooring systems, and as a moisture mitigation layer beneath tile, carpet, or hardwood flooring. Application is suited to interior concrete slabs that have passed moisture testing thresholds for standard coatings but still require a vapor-blocking primer layer before proceeding with topcoats.
Compatible with most floor coating technologies including acrylic, epoxy, and polyurethane topcoats. Can also be used as a moisture barrier beneath tile, carpet, or hardwood flooring installations. Requires Activator part number 277500 for proper mixing and cure.
This product is a two-component epoxy system and must be mixed with its activator before application — consult the product data sheet for mix ratio and pot life. Apply only when air, material, and floor temperatures are between 60 and 80 degrees F; do not apply in direct sunlight or when temperatures are rising. Concrete surface preparation, including mechanical profiling per ICRI guidelines, is required to achieve specified adhesion. Power down any HVAC systems that could introduce contaminants to the wet film, and ensure adequate ventilation during application and cure.
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