Almost every paint failure on a Nigerian wall is a preparation or moisture problem that the topcoat was asked to cover up. Painting over the symptom is how people end up repainting the same wall every year.
The symptom tells you which problem you have. This guide covers the eight you are most likely to meet, what causes each one, and what has to happen before any paint goes on.
1. The wall rubs off on your hand
That is chalking. The binder in the paint film has broken down and the pigment is sitting loose on the surface. It happens with cheap high-pigment paints, with paint that has been over-thinned, and with old paint that has simply reached the end of its life under strong sun.
It matters because you cannot paint over it. A new coat bonds to the loose powder, not the wall, and will do exactly the same thing within a year.
The fix: wash the chalk off — a stiff brush and water, repeated until the water runs clear — then let the wall dry completely and prime before recoating.
2. The paint lifts in sheets or flakes
Peeling in sheets usually means the surface underneath was dusty, greasy or glossy when it was painted. Paint bonds mechanically; on a dusty wall there is nothing to grip, so the whole film releases together.
Flaking in small patches is more often moisture. Water is coming through the wall from outside, from a leaking pipe, or from a bathroom on the other side, and it pushes the paint off from behind.
The fix: scrape back to a sound edge, feather with sandpaper, find and fix any water source, prime the bare areas, then repaint. Painting over flaking without removing it just delays the same failure.
3. Bubbles or blisters under the paint
Moisture again, but this time trapped. Either the wall was still damp when it was painted, or the coat was applied in the middle of the rainy season when the air was too humid for the film to cure properly.
Blisters will not flatten on their own. They have to be scraped back to sound paint, the wall allowed to dry, and the area reprimed.
4. White powder or salt on the surface
That is efflorescence — salts in the masonry being carried to the surface by water and crystallising as the water evaporates. It looks like a paint problem and is entirely a moisture problem.
The fix: brush it off dry, then deal with the water path. Coating over efflorescence without stopping the moisture traps the salts and they push the new paint off within months. Once the wall is dry and the source fixed, seal and repaint.
5. Damp patches that keep coming back
Rising damp at the base of a wall, a patch under a window, or a ring around a downpipe. Water is entering the structure, and no coating stops it.
The fix: find the source — failed damp course, cracked render, blocked drainage, leaking gutter, plumbing — and repair that first. Then let the wall dry out, which can take weeks, before priming and painting. This is a building job, not a painting one, and any contractor who offers to “seal it” without finding the leak is selling you a repeating problem.
6. Black or green patches
Mould and algae, which need damp and no airflow. Behind wardrobes, in bathrooms, on north-facing exterior walls and on walls shaded by a neighbouring building.
The fix: wash with a bleach solution to kill it, rinse, let the wall dry, and use a washable finish — Prestige Satin Finish in bathrooms and kitchens, rather than matt. Then improve the ventilation, because paint alone will not stop it returning.
7. Brown or yellow stains that bleed through
Water stains, smoke, nicotine or old cooking grease. These are not just marks on the surface; they are in the plaster, and a normal topcoat will let them bleed through again.
The fix: find and fix the leak if it is water. Then seal the stain with a stain-blocking primer before painting. Paint alone does not block a stain, whatever the tin says about coverage.
8. Hairline cracks across the plaster
Most hairline cracking is movement — thermal, or settlement in new blockwork. It is rarely structural, but it always telegraphs through a thin paint film.
The fix: open the crack slightly, fill with Prestige Super Filler, sand flush, and prime. A crack that reopens repeatedly, or one wide enough to take a coin, needs a builder rather than a painter.
Painting over glossy or previously glossed walls
A hard, shiny old finish gives nothing for new paint to grip. Wash it, sand it to a dull key, and use a suitable primer. Skipping the sanding is why new paint sometimes peels off in sheets from an otherwise sound wall.
Where a wall is going back to matt or satin, the sanding is still needed; the new finish does not care what the topcoat is, only what it is bonding to.
New plaster and concrete
New plaster has to cure before it is painted — typically several weeks, longer in humid weather. Painting too early traps moisture in the plaster, and the paint blisters as it escapes. Then the wall needs sealing before the first coat, because bare plaster absorbs unevenly and gives a patchy finish.
We cover this in more detail in our guide to ceilings and POP, where the same principle applies.
The preparation that prevents all of it
- Wash the wall, and let it dry completely. Chalk, grease and dust all have to go
- Scrape back anything loose, flaking or blistered to a sound edge
- Fill cracks and hollows, then sand flush. A filled patch that is not sanded shows through the topcoat
- Fix the water before you fix the paint. Leaks, gutters, cracked render, failed flashing
- Prime, especially new plaster, filled patches and any bare surface
- Two coats, on a dry wall, in dry weather
The single most common mistake is painting over a chalky wall because it looks fine in the shade. It will look fine for about four months.
Which product where
- Prestige Super Filler — cracks, holes and hollows before painting
- Prestige Matt Finish — interior walls in sound condition, dry rooms
- Prestige Satin Finish — bathrooms, kitchens and anywhere the wall gets wiped
- Prestige Textured Finish — exterior walls that take driving rain
If you are not sure what you are looking at
Send us a photograph of the wall and tell us how long the problem has been there. We will tell you what is causing it and what the wall needs before paint. Call +234 802 562 5333, message WhatsApp, or send your project details.