Surface Preparation · 5 min read · Beginner
How to Prepare Walls Before Painting
90% of a quality paint job is in the preparation. Learn how to wash, fill, sand, and seal walls.
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Key points & steps
- Inspect the wall in raking light (hold a torch at an angle) to spotlight dents, scratches, and lumps.
- Scrape off any flaking paint or degraded plaster back to a sound base.
- Wash thoroughly with diluted sugar soap to dissolve airborne cooking grease, smoke, and grime.
- Fill cracks and picture-hook holes with ready-mixed interior filler, pressing deep into the void.
- Sand flat with fine 120-grit paper once dry. Wipe away gypsum dust with a tack cloth.
- Apply decorator’s caulk along the junction between skirting boards and walls for seamless lines.
Practical tips
- Slightly overfill deep holes because water-based filler shrinks slightly as it cures.
- Wait at least 2 hours before painting over flexible acrylic decorator’s caulk.
What you may need
- Sugar soap
- Ready-mixed filler
- Filling knife
- 120-grit sandpaper
- Decorator’s caulk
- Caulking gun