How to prepare a wall before painting
To prepare a wall before painting, you need to clean it, repair any defects, sand it and let it dry. Only then do you apply primer, if needed. It may seem like extra work, but preparation is what decides whether the paint ends up smooth and lasts for years. Painting over dust, grease or loose paint is the most common cause of bubbles and peeling.
1. Empty and protect the room
Take down pictures, mirrors and curtains, and remove the socket covers. Move the furniture to the centre of the room and cover it. The clearer the wall, the faster and better you can work. Keep the cover screws in a bag so you do not lose them.
2. Take a good look at the wall
Run your hand over the wall and look along it from the side, with a torch or your phone light held against the surface. This shows up holes, scratches, cracks and areas where the old paint is loose. Mark those spots with a pencil.
Also look out for dark stains or paint that looks swollen. This could be damp. If the cause is not fixed, the stain will come back no matter how much paint you put on top. In that case, deal with the source of the problem first.
3. Clean the surface
Paint does not stick well to dust or grease. Start by removing dust with a soft brush or a dry cloth. Then wash with a damp cloth and water with a little mild detergent.
- In the kitchen, clean grease off thoroughly around the hob and the extractor hood.
- In the bathroom, remove mould with a suitable product and let it dry.
- Around light switches and doors, wipe off fingerprints.
- Go over the wall with a cloth and plain water to remove any detergent residue.
Let the wall dry completely before the next step. A damp wall should not be painted.
4. Repair and sand
Scrape off loose paint with a scraper. Fill holes and cracks with filler and let it dry for as long as the manufacturer says. Then sand the filled areas until they are level with the wall. Another article explains step by step how to fill holes and cracks.
If the wall is already painted with a gloss paint, give the whole area a light sanding. This gives the new paint something to grip. Then wipe off the dust with a slightly damp cloth.
5. Primer: when you need it
Primer is a base coat that helps the paint adhere and look even. It is not needed on every wall, but it helps a lot in these cases:
- A new wall, plastered or skimmed, that has never been painted.
- Areas repaired with filler, which absorb paint differently.
- Going from a dark colour to a light one.
- Walls that give off dust when you run your hand over them.
Always read the tin to find out which primer suits each surface and how long you should wait before painting.
6. Get everything else ready before opening the paint
Stick masking tape along the skirting boards and around door and window frames. Cover the floor with plastic sheeting or a dust sheet. Open the window for ventilation, but avoid strong draughts and direct sun on the wall, because the paint can dry too fast.
Tip: Do this final check before painting: run your hand over the wall. If you feel dust, roughness or damp patches, go back and sort them out. Ten minutes now will save you hours of touching up later.