Zinsser Block Filler 2X Primer is a high-build acrylic primer designed for interior and exterior residential, commercial and industrial applications. It has twice the thickness of other primers to fill pinholes and seal voids in concrete block and masonry, resulting in a smoother and more uniform topcoat. Block Filler 2X tolerates high pH levels (up to 13) in new concrete and masonry and provides excellent alkali and efflorescence resistance. It can be applied to new masonry surfaces prior to a full 30-day cure. Block Filler 2X high hiding formula seals semi-porous surfaces to provide better topcoat coverage and consistent sheen without pinholing.
Block Filler 2X provides excellent adhesion on all types of bare or previously painted surfaces, such as concrete, concrete/cinder block, brick, stucco, fiber cement siding, plaster, mortar, concrete masonry units (CMU) and other cementitious surfaces. Block Filler 2X fills voids in concrete, resolves mortar burns, delamination and film void issues. Block Filler 2X may be used with most water or solvent-based topcoats, including Rust-Oleum High Performance 9100 system DTM Epoxy mastic and High Performance 9800 System DTM Urethane Mastic.