Inspect before reaching for a roller
Look across the wall in natural and raking light. Check for flaking edges, cracks, dents, old repairs, water stains, chalkiness and glossy areas. Rub the coating with a clean hand and test suspect edges gently rather than assuming the entire wall is sound.
Moisture marks or active leaks need their cause resolved and the substrate dried before decorating. Paint is a finish, not a repair for water entry.
Professional wall preparation sequence
Wash and degrease
Use sugar soap or a suitable degreaser to remove grime, cooking film and hand marks. Rinse as directed and allow the wall to dry.
Scrape unsound paint
Remove flaking paint back to firmly bonded material, then feather the sound edges so they do not telegraph through the finish.
Fill holes and cracks
Use an appropriate interior filler for nail holes, dents and stable cosmetic cracks. Ongoing movement or moisture must be addressed before repainting.
Sand smooth
Sand repairs and sound coatings with a fine 180–240 grit abrasive. Existing gloss or semi-gloss areas need an even de-glossed key.
Remove every trace of dust
Vacuum ledges, corners and the wall, then use a clean microfibre cloth. Residual dust weakens adhesion and spoils the finish.
Prime before topcoats
Spot-prime filler and bare areas. Use a full sealer or undercoat where porosity, stains, extensive repairs or a coating change makes it necessary.
Warning signs the preparation is incomplete
- Loose edges lift when lightly scraped or sanded.
- The wall still feels greasy, dusty or chalky after cleaning.
- Repairs remain proud, hollow or visibly ridged under side light.
- Glossy patches remain beside dull areas, creating an uneven surface for the new coating.
Why primers and sealers matter
Spot primer stops porous filler from drawing binder out of the topcoat and showing as dull patches. A full sealer or undercoat creates a consistent base when repairs are extensive or the existing surface is unsuitable for direct coating.
Previously painted gloss surfaces require more than a quick sand. Our guide to painting over gloss explains the cleaning, de-glossing and adhesion-primer sequence in detail.