CSLB C-33 Painting & DecoratingSurface PreparationMedium
A painting contractor is preparing an exterior wood siding for repainting. They observe areas with significant dirt, mildew, and some loose chalky residue. What is the most effective initial cleaning method for this surface before any scraping or sanding?
- APower washing with a mild detergent solution
- BWiping down with mineral spirits
- CHand scrubbing with a dry brush
- DSanding with coarse-grit sandpaper
Show answer & explanationAnswer & explanation
Correct answer: A. Power washing with a mild detergent solution
Power washing with a mild detergent solution is highly effective for removing dirt, mildew, and loose chalk from exterior wood siding. It cleans the surface thoroughly without excessive abrasion, preparing it for subsequent scraping, sanding, and priming.
Why the other options are wrong
- B. Mineral spirits are for degreasing and cleaning specific residues, not for general dirt and mildew removal.
- C. Dry brushing is insufficient for removing ingrained dirt, mildew, or chalky residue effectively.
- D. Sanding should occur after initial cleaning, as sanding over dirt and mildew can embed contaminants and clog sandpaper.
Exterior Wood Cleaning
The process of thoroughly cleaning exterior wood surfaces to remove dirt, mildew, and loose contaminants before painting or staining.
- Essential for paint adhesion and longevity.
- Power washing with detergent is a common effective method.
- Requires proper drying time before further steps.
Memory trick: Power wash, Detergent, Dry: The Triple Threat to Exterior Grime.