CSLB C-33 Painting & DecoratingSurface PreparationMedium
A painting contractor is preparing a newly constructed concrete block wall for painting. The wall is very porous, and the client desires a smooth, uniform finish. What type of primer is essential to achieve this outcome?
- AOil-based alkyd primer
- BWater-based latex primer
- CBlock filler primer
- DClear sealer primer
Show answer & explanationAnswer & explanation
Correct answer: C. Block filler primer
Concrete block walls are highly porous and uneven. A block filler primer is specifically designed with a high solids content to fill small voids and pores, creating a smoother, more uniform surface for the finish coat and improving paint coverage.
Why the other options are wrong
- A. Oil-based alkyd primers provide good adhesion but lack the high-build properties needed to fill block pores.
- B. Water-based latex primers are too thin to effectively fill the pores of concrete block.
- D. Clear sealer primers are generally used to seal porous surfaces against moisture but do not provide the filling properties for a smooth finish.
Block Filler Primer
A high-build primer specifically formulated to fill the pores and voids in porous masonry surfaces like concrete block, creating a smoother, more uniform substrate.
- Essential for achieving a smooth finish on concrete block.
- Reduces the amount of finish paint needed.
- Improves adhesion and uniformity of the topcoat.
Memory trick: Porous blocks need a filler, make it smooth, paint it chiller.