NASCLA Accredited Commercial General ContractorFinishesMedium
A contractor is preparing to apply a finish coat of paint to an exterior wood siding that has been previously painted and is now exhibiting significant chalking and minor peeling. Which type of primer is most appropriate for ensuring good adhesion and a durable finish?
- AOil-based enamel primer
- BWater-based latex primer
- CShellac-based primer
- DAlkyd-based bonding primer
Show answer & explanationAnswer & explanation
Correct answer: D. Alkyd-based bonding primer
Alkyd-based bonding primers are specifically formulated to penetrate porous, chalky, or slightly peeling surfaces, providing excellent adhesion for subsequent finish coats on exterior wood.
Why the other options are wrong
- A. Oil-based enamel primers are generally used for new wood or metal, but may not offer the best penetration and bonding on chalky surfaces.
- B. Water-based latex primers are versatile but may struggle with deep penetration and bonding on heavily chalking or peeling exterior wood, potentially re-emulsifying old chalk.
- C. Shellac-based primers are excellent for stain blocking and sealing odors, but are not typically the primary choice for improving adhesion on chalking exterior wood.
Alkyd-based bonding primer
A type of primer formulated with alkyd resins, known for its excellent adhesion and penetration, especially on challenging surfaces like chalking or peeling paint.
- Good for chalky surfaces
- Excellent penetration
- Provides strong adhesion for topcoats
Memory trick: Chalky wood needs a strong 'Alkyd' bond to keep the paint from flaking off.