Most paint problems come down to one of three things: moisture reaching the film, a surface that was not prepared or primed correctly, or the wrong product for the conditions. Diagnose the cause first — fixing the symptom without the cause just brings the problem back. This guide walks through the paint defects we see most often on South African homes and buildings, what causes each, and how to fix it with the right Rhinoluxe product. Use it to identify your problem, then follow the linked guide for the full method.
How to diagnose a paint problem
Start with the pattern and the location: is the surface wet or damp, is the paint coming off in sheets or powder, and is the fault in the top coat only or right down to the substrate? Moisture-driven faults (blistering, flaking, mould, efflorescence) cluster near ground level, parapets, leaks and wet rooms. Preparation faults (peeling, chalky-substrate flaking, poor adhesion) show as clean separation between coat and wall. Product faults (fading, chalking, dirt pickup) appear on the most sun- and weather-exposed elevations. Get the cause right and the correct fix below follows naturally.
Quick diagnosis table
| What you see | Likely cause | Fix / guide |
|---|---|---|
| Black, grey or green growth on the wall | Damp + shade; mould/algae | Remove mould from walls |
| Paint peeling or flaking off in sheets | Moisture or poor prep/adhesion | Peeling & flaking paint |
| Cracks in the wall or paint film | Plaster/movement or thick film | Cracks before painting |
| White powdery salts on masonry | Efflorescence (moisture-borne salts) | Stop efflorescence |
| Rust bleeding through / metal corroding | Unprotected or poorly primed steel | Rust removal / rust converter |
| Powder rubs off a weathered coat | Chalking (UV breakdown of binder) | Wash + Bonding Liquid → recoat |
| Varnish greying / lifting on timber | UV + moisture on wood | Wood care guide |
| Floor coating flaking / oil-stained | Wrong coating or unclean concrete | Floor paint guide |
Mould, algae and black growth on walls
Black, grey or green growth means moisture and shade, not “bad paint” — so kill and remove the growth, fix the damp source, and only then repaint, ideally in a wipeable finish. Painting over mould just feeds new growth under the film. Remove it, address the leak, rising damp or condensation feeding it, let the wall dry, and repaint high-risk areas (bathrooms, kitchens, shaded south walls) in a washable enamel like High Sheen or Eggshell Enamel that you can clean. Full method: how to remove mould from painted walls. Where damp is the root cause, see the damp walls guide.
Peeling, flaking and blistering
When paint lifts off in sheets or bubbles, the bond has failed — almost always because it was applied over a damp, dirty, chalky or unprimed surface, or moisture is pushing from behind. Blisters filled with water point to moisture ingress; clean separation over a powdery layer points to painting on a chalky or unsealed substrate. The fix is to strip the loose paint, cure the cause, and re-establish a sound base with Clear Bonding Liquid or Plaster Primer before recoating. Full diagnosis tree: why is my paint peeling and flaking.
Cracks in walls and paint
Fine hairline and craze cracks are usually in the plaster or paint film and are cosmetic; straight or stepped cracks wider than about 0.5 mm are structural and need a specialist before any painting. Cosmetic cracks are filled, bonded and over-coated — a flexible, higher-build system hides fine cracking better than a thin coat. Structural cracks will keep reopening through paint, so they are repaired (or turned into movement joints) first. How to tell them apart and prep correctly: how to fix cracks in walls before painting.
Efflorescence and white salts on masonry
Random white powdery salts on brick or plaster are efflorescence — salts carried to the surface by moisture moving through the masonry, made worse on dark colours. It is a moisture symptom, not a paint fault: remove or seal the moisture source, brush and wash off the salts, let the wall dry for a couple of weeks, then prime with a masonry primer and recoat. If salts keep returning, the water problem is unresolved. Full method: how to stop efflorescence.
Chalking and fading on exposed walls
A powder that rubs off a sun-weathered coat is chalking — UV and weather breaking the binder down and freeing pigment; uniform colour loss on the sunniest walls is fading. Both come from UV on lower-durability or interior-grade paint used outdoors. Scrub off the loose chalk, and if powder persists, bind the surface with Clear Bonding Liquid or an alkali-resistant Plaster Primer before recoating with a quality exterior product. Don’t confuse chalking with fading: if wiping the powder away restores the colour, it is chalking.
Rust and failures on metal
Rust bleeding through paint, flaking off steel or appearing as blisters means corrosion was not removed or the metal was not correctly primed for the exposure. Remove the rust, then either strip back and prime bare steel with an anti-corrosive primer, or neutralise and lock in light surface rust with a rust converter. Our ZP4 neutralises and encapsulates rust in one step (the rust-converter route), while Rust Remover plus Red Oxide Primer handles full strip-and-prime. See rust converter, rust removal, and for new galvanised, how to paint galvanised metal.
Wood and timber coating failures
Greyed, flaking timber and lifting varnish come from UV, moisture through unsealed end-grain, and a lack of maintenance — wood moves, so it needs a flexible, UV-stable finish and periodic recoating. Strip back to sound, sanded timber, seal the ends, and rebuild with a penetrating oil or a UV-stabilised varnish rather than a rigid film that cracks. Route to Premium Wood Oil or Wood Copal Varnish; full guidance in the wood care guide.
Floor and concrete coating failures
Floor paint that flakes, lifts or stains usually means the concrete was oily, dusty, damp or coated with the wrong product for the traffic. Degrease with Industrial Degreaser, confirm the slab is dry and sound, then use a floor-grade coating such as Concrete Enamel or 1K Polyurethane. See the floor paint guide.
Application defects: runs, poor coverage, roller marks
Sags and runs, patchy hiding, roller striations and touch-up differences are application faults — fixed by technique and the right product, not by more paint. Most come from over-loading, spreading too thin, re-working partly dried paint, or a low-flow product. Sand back dried defects and recoat evenly, in the correct conditions, with a good-flow paint and the right roller cover. Colour-match and work edge-to-edge to avoid touch-up patches. The surface preparation guide covers doing it right from the start.
The one rule behind every fix
Clean, sound, dry, and correctly primed — in that order — is what every remedy on this page comes back to. Kill and remove contamination (mould, salts, chalk, rust, oil), fix the moisture or movement causing it, prime or bond the surface so the new coat has something solid to grip, and finish with a product matched to the exposure. Skip a step and the problem returns. When in doubt on the right product for your surface, call +27 84 985 6141 or visit our paint shops in Table View and Edenvale.
