How to prepare your walls before painting
Most paint failures are preparation failures. The steps that decide whether a finish lasts two seasons or ten.
By Tunde Bakare · · 1 min read
Paint does not fail on its own. It fails because of what was underneath it.
Start with a dry surface
Moisture trapped under a coating has nowhere to go. When the sun heats the wall that water becomes vapour and pushes the paint off from behind — the blistering visible on so many buildings by their second year.
Give new plaster at least four weeks to cure. On an existing wall, wait for three consecutive dry days.
Remove what is already loose
- Scrape back anything flaking. New paint over loose paint fails at the same speed as the layer beneath it.
- Wash off algae and mould with a diluted bleach solution, then rinse properly.
- Fill hairline cracks before priming, never after.
Prime
Primer is the layer doing the adhesion work. On bare or patchy masonry it is the difference between a coating that sits on the surface and one that bonds to it.
Skipping primer to save a day is the single most expensive shortcut in painting.
Then paint, properly spaced
Apply the second coat only once the first is genuinely dry, not merely touch-dry. Rushing this is why a finish looks patchy in raking light.