About GAF Bleed-Block Asphalt Primer

GAF Bleed-Block Asphalt Primer is a one part water-based primer designed to block asphaltic bleed through from existing asphaltic roofing systems. GAF Bleed-Block Asphalt primer increases the adhesion of GAF High Solids Silicone over asphaltic assemblies. Bleed-Block Asphalt Primer can be applied by brush, roller, and airless spray equipment.

Features & benefits

Video playlist thumbnail of a contractor holding a brush treating roofing seams with GAF Silicone Mastic

GAF Silicone Coatings Installation Guide

As an easy-to-apply roof coating, silicone creates a highly flexible and monolithic membrane that offers unrivaled ponding water resistance and excellent UV protection, and won’t degrade, chalk, or crack from prolonged exposure to direct sunlight. Learn installation techniques from the pros.
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Seal the Deal: Keep Your Silicone Coating Looking Its Best

In this quick video, you'll see how this water-based primer plays a key role in protecting against asphalt bleed-through and staining. Whether you're working on a recovery or maintenance project, Bleed-Block helps ensure a clean, professional-looking finish.

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    Installation showcase

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