Get the better of common paint problems right here with pro-tips from the market leaders in paint.
Problem
Alligatoring is when the pattern of the cracking in the paint film resembles the scales of an alligator. These cracks generally do not expose the substrate (e.g. the surface that has been painted).
Possible causes
- Application of an extremely hard, rigid coating, such as an alkyd enamel, over a more flexible coating, such as a water-based primer.
- Application of a topcoat before the undercoat is completely dry.
- Natural aging of oil-based paints as temperatures fluctuate (the constant expansion and contraction result in the loss of paint film elasticity).
Solution
- Remove the old, affected coating, either mechanically through scraping and sanding, or by using a paint remover or heat gun.
- The surface should then be primed with a suitable primer, before repainting with a suitable quality topcoat.
- The primer selection will depend on the type of surface to be primed and the topcoat selection will depend on the environment that the application will be exposed to.
Problem
Burnishing is evident in an area that shows an unwanted increase in the gloss or sheen of a paint film when it is subjected to rubbing or scrubbing, or has an object brush up against it.
Possible causes
- The use of matt paint in high-traffic areas, where a sheen paint would have been more desirable.
- Frequent washing and spot cleaning.
- Use of lower grades of paint with poor stain and scrub resistance.
- Washing of the painted surface with cleaning products containing ammonia.
Solution
- Paint heavy-traffic areas that require regular cleaning with a top-quality, washable product.
- Rather use a low sheen, washable product than a matt-finish product.
- Clean painted surfaces with a soft cloth or sponge and non-abrasive, paint-friendly cleansers.
Problem
Chalking is the formation of a fine, white powder on the surface of the paint film due to weathering, which may give the appearance of colour fading.
Possible causes
- The use of a low-grade, highly pigmented paint.
- The use of an interior paint for an outdoor application.
- Over-exposure of a coating with inadequate ultraviolet (UV) resistance.
- Painting of acrylic primers on walls with moisture contents of higher than 15%.
- Over-thinning of a coating.
- Over-spreading of the primer and/or the topcoat.
Solution
- Scrape or sand the substrate to remove wrinkled coating.
- If using a primer, allow it to dry completely before applying a high-quality topcoat.
- The primer selection will depend on the type of surface to be primed.
Problem
Damp is the presence of unwanted moisture in the structure of a wall, and the result of either intrusion from the outside or condensation from within the structure.
Possible causes
- Leaking roofs.
- Defects in and around chimneys.
- Defects in gutters and downpipes.
- Penetrating dampness through walls, around windows, windowsills, parapet walls and cracks in plaster.
- Rising damp.
- Groundwater and capillary movement.
- Leaking pipes
Solution
- Painting over damp areas without fixing the problem is a fruitless exercise.
- It is advisable to consult your paint distributor or manufacturer’s technical department for the correct advice to resolve the damp problem before proceeding with the painting process.
Problem
Efflorescence is visible as soluble salts that form on the surface of plaster or brickwork, usually visible as loose white powder or as feathery crystals.
Possible causes
- Failure to adequately prepare the surface by removing all current traces of efflorescence.
- Insufficient curing time for new cement before painting.
- Contamination from seawater spray or exposure of unpainted masonry to the elements for long periods of time.
- Using a primer with low alkali resistance.
- Failure to attend to all the waterproofing aspects prior to painting.
Solution
- No remedy other than to prevent it from occurring by eliminating abnormal moisture levels in the masonry surface.
- Remedy the cause of the excessive moisture in the masonry first.
- Remove the efflorescence and all other loose material with a wire brush, power brush or low-pressure washing, and then thoroughly rinse the surface and allow it to dry out.
- When all traces of efflorescence have been removed, prime, allow it to dry for 24 hours and apply a suitable quality topcoat.
Problem
Fungal growth or mould is visible as a green, black or brownish-red growth on the surface of paint.
Possible causes
- Forms most often on painted areas where the surface tends to be damp, or where it receives little or no direct sunlight.
- The application of paints that are not formulated to stand up to areas exposed to high humidity, condensation and poor ventilation on a daily basis, for example, bathrooms, kitchens and laundry rooms.
- Failure to prime bare wooden surfaces with a suitable primer before applying the topcoat.
- Painting over a surface or coating that is contaminated with fungal spores.
Solution
- Apply a 4:1 water/HTH (chlorine) or 4:1 water/JIK (sodium hypochlorite), or a suitable anti-fungal mixture to the affected surface area.
- Allow to react for the specified time before washing off with water and a nylon brush.
- Repeat this process if any traces of fungal spores are still visible on the treated surface.
- Neutralise the areas with a cleaning solution, rinse off with clean water and allow to dry.
- Apply a suitable primer, followed by a high-quality topcoat that is suitable for the environment that it will be exposed to.
- To avoid future mould walls, ensure proper ventilation, turn on extractor fans or use de-humidifying units.
Problem
Mud cracking is deep, irregular cracks resembling dried mud in the dry paint film.
Possible causes
- Paint is applied too thickly, usually over a porous surface.
- Paint is allowed to build up in corners during application.
- Paint is applied too thickly, to hide the inherent poor coverage of a lower quality paint.
Solution
- Remove mud cracking by scraping and sanding back to a sound, smooth surface finish.
- Prime repaint using a premium quality primer and paint.
- This type of paint is likely to prevent the recurrence of mud cracking, because it is relatively flexible compared to alkyd, oil-based and ordinary PVA paints.
- High-quality paints have a higher solids content, which reduces the tendency to mud crack.
- They also have very good application and hiding properties, which minimise the tendency to apply a too thick coat of paint.
Problem
Surface imperfections such as noticeable cracks and holes in the painted wall surface.
Possible causes
- Poor plastering or rendering of the wall surface.
- Old, damaged plaster or wall render.
- Movement of the building may cause cracks.
- Holes left after the removal of fixtures.
Solution
- Remove any dust from inside the holes.
- Apply an all-purpose filler using a knife or spatula. Wipe away any excess filler and smooth the surface.
- For deep holes, it’s best to wait for each layer of filler to dry before applying the next.
- Sand the area with a dry piece of sandpaper, then cover it with a layer of primer or a thinned coat of paint, and finally paint over the whole wall.
Problem
Visible application marks such as roller marks or brush strokes.
Possible causes
- Poor application, incorrect rollers and brushes.
- Long pile rollers can trap too much paint and leave roller marks.
Solution
- The ideal roller has a medium “pile” (thickness).
- Avoid buying cheap foam rollers as these absorb more water than more expensive, high-quality rollers.
- Synthetic bristle brushes work best on water-based paints, as they absorb less water, helping to eliminate heavy brush marks.
- When painting a tight space, use a brush with tapered bristles.
- When using a brush to “cut in”, choose an angled brush with one side longer than the other.
Full acknowledgement and thanks go to Prominent Paints, Dulux and Plascon for the information in this editorial.