Why is my paint patchy?
Absorbency, coverage and technique — the three causes, and how to tell which one you have.
- Difficulty
- beginner
- Time
- 30 min
- Read
- 2 min
Short answer
Usually the wall is absorbing unevenly, which needs a primer or a mist coat rather than a third topcoat. Patchiness that follows filler and repairs is always this, and more paint will not fix it.
Patchy paint is nearly always the surface underneath rather than the paint. Different areas absorb at different rates, so the same coat dries to different sheens — and adding more topcoat on an unsealed surface repeats the problem.
Step by step
- Look at where the patches are.Following filled holes and repairs means uneven absorbency. Random or streaky means application. Following the previous colour means coverage. Each has a different fix.
- Seal an absorbent surface.New plaster, filler, or bare patches drink paint. A mist coat — emulsion thinned with about 10-20% water — or a proper primer seals it so the topcoat sits evenly.
- Prime over repairs, not just over the whole wall.Filler absorbs differently from the surrounding paint. Spot-priming every repair is what stops them showing through, and it is the most commonly skipped step.
- Use enough paint.Under-loading the roller is a very common cause. The roller should be well loaded and rolled out, not squeezed nearly dry.
- Keep a wet edge.Work in sections and always roll back into paint that is still wet. Painting over a section that has started to dry leaves a visible lap mark.
- Roll in a consistent direction to finish.Load and spread in any direction, then finish each section with light parallel strokes in the same direction. It evens the texture.
- Apply two full coats, and let the first dry properly.Most colours need two. Recoating before the first has dried drags it and creates patches. Follow the tin's timing.
- Do not overwork it.Going back over paint that has begun to set drags the film and leaves marks. Lay it on, spread it, leave it.
Tips
- Light raking across a wall from a window shows every flaw. Check with a torch held near the wall before deciding the job is done.
- Cheap paint covers poorly and needs more coats. The expensive tin is often cheaper by the time the wall is finished.
- Do not judge until it is completely dry. Emulsion frequently looks patchy while drying and evens out.
If it doesn't work
Patches following filler and repairs
Cause: Uneven absorbency — Fix: Spot-prime the repairs, or mist coat the whole wall, then repaint.
Streaky and uneven overall
Cause: Not enough paint, or worked too long — Fix: Load the roller properly and apply a full second coat without overworking it.
Visible lines between sections
Cause: Lost the wet edge — Fix: Work in smaller sections, faster, always rolling back into wet paint.
Old colour showing through
Cause: Insufficient coverage — Fix: Two full coats, and a tinted primer if going from dark to light.
Questions people ask
Why is my paint patchy after two coats?
The surface is absorbing unevenly, usually because of filler or bare patches. Prime or mist coat first — a third topcoat will not fix it.
What is a mist coat?
Emulsion thinned with 10-20% water, applied to bare plaster or filler to seal it. It stops the topcoat soaking in unevenly.