NASCLA Accredited Commercial General ContractorFinishesMedium
A painter is preparing to apply a finish coat to interior gypsum board walls that have been previously painted with a glossy, oil-based enamel. The new finish will be a water-based latex paint. What is the most critical preparatory step to ensure proper adhesion and prevent peeling of the new paint?
- AApply a skim coat of joint compound over the entire surface.
- BWash the walls with a strong detergent and rinse thoroughly.
- CLightly sand the glossy surface and apply an adhesion primer.
- DApply a second coat of the existing oil-based enamel.
Show answer & explanationAnswer & explanation
Correct answer: C. Lightly sand the glossy surface and apply an adhesion primer.
Glossy surfaces provide poor adhesion for new paint, especially when switching from oil to water-based. Lightly sanding creates a 'tooth' for mechanical adhesion, and an adhesion primer provides a chemical bond between dissimilar paint types.
Why the other options are wrong
- A. A skim coat of joint compound is for smoothing imperfections, not for promoting adhesion over existing glossy paint.
- B. Washing removes dirt but does not create the necessary surface profile for adhesion on a glossy surface.
- D. Applying more oil-based enamel prevents the desired switch to latex and doesn't solve adhesion issues for the new paint.
Adhesion Primer (Glossy Surfaces)
A specialized primer formulated to bond to difficult, non-porous, or glossy surfaces, providing a suitable base for subsequent paint coats.
- Essential when painting over glossy finishes, ceramic tile, or laminates.
- Creates a 'bridge' for new paint to adhere, preventing peeling.
- Often requires light sanding of the glossy surface for optimal performance.
Memory trick: To make new paint stick to gloss, ROUGHEN and PRIME like a boss.