How to prep a wall before painting

A good finish is mostly preparation. When paint peels, bubbles or looks patchy within a year, poor prep is almost always the reason, not the paint. The work below takes an afternoon on an average room and saves you redoing the whole job later.

1. 1

   Clear and protect the area

   Move furniture out or into the middle and cover it. Lay drop sheets, and mask skirtings, window frames and switches with painter’s tape. Ten minutes here saves an hour of cleaning splatters later.

2. 2

   Clean the surface

   Paint sticks to a clean wall, not to dust and grease. Wash interior walls with sugar soap, paying attention to kitchen and passage walls where hand marks and cooking grease build up. Outside, scrub the wall down and rinse. If you see mould or black speckling, treat it with a fungicidal wash first and let it work before rinsing.

3. 3

   Scrape and sand

   Scrape off any flaking or loose paint back to a firm edge. Lightly sand glossy or previously enamelled areas so the new coat has something to grip. Wipe or dust off afterwards.

4. 4

   Fill and repair

   Fill cracks and holes with the right product: a flexible crack filler for hairline cracks, and a skimming or wall filler for larger dents and uneven patches. Let it cure fully, then sand it flush with the surrounding wall.

5. 5

   Prime the bare and repaired spots

   Spot-prime any bare plaster, filler and stains. New, porous or problem surfaces (fresh plaster, water-stained ceilings, chalky old paint) should be fully primed with the correct primer. This is what stops filler patches and stains grinning through the topcoat.

6. 6

   Final wipe and check

   Dust the wall down one last time and make sure everything is properly dry. Filler and primer that look dry on top can still be damp underneath, so give them the time on the tin before you start your first coat.

The mistakes we see most often

• Painting over dust, cobwebs or greasy walls, so the paint never keys properly.
• Skipping primer on new plaster, which drinks the topcoat and leaves a patchy sheen.
• Painting over mould without treating it first. It grows straight back through the new paint.
• Rushing the filler. If it isn’t cured and sanded flat, every patch shows in the finish.

Not sure which filler or primer your wall needs? Bring us a photo, or describe the surface at the counter, and we’ll match the right products to the job before you spend on paint.