CSLB C-33 Painting & DecoratingSurface PreparationMedium
A painting contractor is preparing to paint a newly constructed concrete block wall in a commercial building. The blocks are porous and exhibit varying degrees of texture. Which type of primer is most essential for achieving a smooth, uniform finish and ensuring proper paint adhesion?
- ABlock filler primer
- BOil-based stain-blocking primer
- CPVA (Polyvinyl Acetate) primer
- DAcrylic latex primer
Show answer & explanationAnswer & explanation
Correct answer: A. Block filler primer
Block filler primer is specifically formulated with high solids content to fill the porous voids and bridge the texture of concrete blocks, creating a smooth, uniform surface for subsequent topcoats and improving adhesion.
Why the other options are wrong
- B. Oil-based stain-blocking primers are used to prevent stains from bleeding through, not primarily for filling texture on concrete blocks.
- C. PVA primers are typically used on new drywall to seal the surface and equalize porosity, but are not designed for the heavy texture of concrete blocks.
- D. Acrylic latex primers are general-purpose but may not adequately fill the porosity of concrete blocks.
Block Filler Primer
A high-solids primer designed to fill porous and textured masonry surfaces, such as concrete blocks, creating a smooth, uniform base for topcoats.
- Reduces paint absorption into porous substrates.
- Improves final finish appearance and paint adhesion.
- Essential for achieving a smooth finish on rough surfaces.
Memory trick: Rough blocks need a 'block filler' to be smooth.