Spot the Problem • Get the Fix
Everyone loves a great painted room — it's welcoming, fun, and often an exciting change unless of course, something goes wrong. Before you have to deal with unsightly paint problems, take a look at the details below to learn what to spot, how to avoid it, and if you can't what you can do to fix it.
Exterior Paint Problems
Patterned cracking in the surface of the paint film resembling the regular scales of an alligator.
- Application of an extremely hard, rigid coating, like a solvent-‐based enamel, over a more flexible coating, like a water-‐based primer
- Application of a topcoat before the undercoat is dry
- Natural ageing of oil-‐based paints as temperatures fluctuate
- The constant expansion and contraction results in a loss of paint film elasticity
Old paint should be completely removed by scraping and sanding the surface; a heat gun can be used to speed work on large surfaces, but take care to avoid igniting paint or substrate. The surface should be primed with a high-quality water-‐based primer, then painted with a top-quality exterior water-based paint.
Bubbles resulting from localized loss of adhesion and lifting of the paint film from the underlying surface.
- Painting a warm surface in direct sunlight.
- Application of oil-‐based or alkyd paint over a damp or wet surface.
- Moisture escaping through the exterior walls (less likely with latex paint than with oil-‐based or alkyd paint).
- Exposure of latex paint film to dew, high humidity or rain shortly after paint has dried, especially if there was inadequate surface preparation.
If blisters go down to the substrate, first try to remove the source of moisture. Remove blisters by scraping, then sanding the surface.
Formation of fine powder on the surface of the paint film during weathering, which can cause colour fading. Although some degree of chalking is a normal, desirable way for a paint film to wear, excessive film erosion can result in heavy chalking.
- Use of a low-‐grade, highly pigmented paint.
- Use of interior paint for an outdoor application.
First, remove as much of the chalk residue as possible, using a stiff bristle brush (or wire brush on masonry) and then rinse thoroughly with a garden hose; or use power washing equipment. Check for any remaining chalk by running a hand over the surface after it dries. If noticeable chalk is still present, apply a quality solvent-‐based or water-‐based primer (or comparable sealer for masonry), then repaint with a quality exterior coating. If little or no chalk remains and the old paint is sound, no priming is necessary and the surface can be repainted with quality exterior paint.
The splitting of a dry paint film through at least one coat, which will lead to complete failure of the paint. Early on, the problem appears as hairline cracks; later, flaking of paint chips occurs.
Use of a lower quality paint that has inadequate adhesion and flexibility.
Over thinning the paint or spreading it too thin.
Poor surface preparation, especially when the paint is applied to bare timber without priming.
Painting under hot or windy conditions that make water-‐based paints dry too fast.
It may be possible to correct cracking that does not go down to the substrate by removing the loose or flaking paint with a scraper or wire brush, sanding to feather the edges, priming any bare spots and repainting.
If the cracking goes down to the substrate, remove all of the paint by scraping, sanding and/or use of a heat gun; then prime and repaint with a quality exterior water-based paint.
Accumulation of dirt, dust particles and/or other debris on the paint film; may resemble mildew.
- Use of a low quality paint.
- Soil splashing onto the substrate.
- Air pollution, car exhaust and flying dust collecting on house body and horizontal trim.
Wash off all surface dirt before priming and painting. If unsure whether the problem is dirt or mildew, conduct a simple spot-‐test (see Mildew). Clean off dirt with a scrub brush and detergent solution, followed by thorough rinsing with a garden hose. Heavier dirt accumulations may require the use of a power washer. While dirt pickup can't be eliminated entirely, top quality exterior latex paints typically offer superior dirt pickup resistance and washability. Also, higher gloss paints are more resistant to dirt pickup than flat paints, which are more porous and can more easily entrap dirt.
Crusty, white salt deposits, leached from mortar or masonry as water passes through it.
- Failure to adequately prepare the surface by removing all previous efflorescence.
- Excess moisture escaping through the exterior masonry walls from the inside.
If excess moisture is the cause, eliminate the source by repairing the roof, cleaning out gutters and downspouts, and sealing any cracks in the masonry with high quality, water-‐based all-‐acrylic caulk. If moist air is originating inside the building, consider installing vents or exhaust fans, especially in kitchen, bathroom and laundry areas. Remove the efflorescence and all other loose material with a wire brush, power brush or power washer; then thoroughly rinse the surface. Apply a quality water-‐ based or solvent-‐based masonry sealer and allow it to dry completely; then apply a coat of top quality exterior house paint, masonry paint or elastomeric wall coating. Dulux recommends Weathershield 10 Low Sheen.
Fading/Poor Colour Retention
Premature and/or excessive lightening of the paint colour, which often occurs on surfaces with sunny exposure. Fading/poor colour retention can also be a result of chalking of the coating.
Use of an interior grade of paint for an outdoor application.
Use of lower quality paint, leading to rapid degradation (chalking) of the paint film.
Use of a paint colour that is particularly vulnerable to UV radiation (most notably, certain bright reds, blues and yellows).
Tinting a white paint not intended for tinting, or over tinting a light or medium paint base.
When fading/poor colour retention is a result of chalking, it is necessary to remove as much of the chalk as possible (see Chalking). In repainting, be sure to use a quality exterior house paint in colours recommended for exterior use.
The appearance of a denser colour or higher gloss where wet and dry layers overlap during paint application.
- Failure to maintain a 'wet edge' when applying paint.
Maintain a wet edge when painting by applying paint toward the unpainted area and then back into the just-‐painted surface. This technique (brushing from "wet to dry," rather than vice versa) will help produce a smooth, uniform appearance. It is also wise to minimize the area being painted and plan for interruptions at a natural break, such as a window, door or corner (especially important when applying stain to bare wood). Solvent-‐based paints generally have superior wet edge properties.
Black, grey or brown areas on the painted surface.
Forms most often on areas that tend to be damp, and receive little or no direct sunlight (the underside of eaves are particularly vulnerable).
Use of lower quality paint.
Failure to prime bare wood before painting.
Painting over a substrate or coating on which mould has not been removed.
Test for mould by applying a few drops of household bleach to the discoloured area; if it disappears, it is probably mildew. Remove all mildew from the surface by scrubbing with a diluted household bleach solution (one-part bleach, three parts water); wear rubber gloves and eye protection. Power washing is also an option. Rinse thoroughly, prime any bare timber, then apply one or two coats of top quality exterior paint.
Nail Head Rusting
Reddish-‐brown stains on the paint surface.
Non-‐galvanized iron nails have begun to rust, causing bleed-‐through to the topcoat.
Non-‐galvanized iron nails have not been countersunk and filled over.
Galvanized nailheads have begun to rust after sanding or excessive weathering.
When painting new exterior construction where non-‐galvanized nails have been used, it is advisable to first countersink the nail heads, then caulk them with a top-quality, water-‐based all-‐acrylic caulk. Each nailhead area should be spot primed, then painted with a quality latex coating. When repainting exteriors, where nailhead rusting has occurred, wash off rust stains, sand the nail heads, then follow the same surface preparation procedures as for new construction.
Loss of paint due to poor adhesion. Where there are a primer and topcoat, or multiple coats of paint, peeling may involve some or all coats.
Seepage of moisture through uncaulked joints, worn caulk or leaks in roof or walls.
Excess moisture escaping through the exterior walls (more likely if the paint is solvent-‐based).
Inadequate surface preparation.
Use of lower quality paint.
Applying a solvent-‐based paint over a wet surface.
Earlier blistering of paint (see Blistering).
Try to identify and eliminate the cause of moisture (see Efflorescence and Mottling). Prepare surface by removing all loose paint with scraper or wire brush, sand rough surfaces, prime bare timber. Repaint with a top-quality water-‐based exterior paint for best adhesion and water resistance.
Poor Alkali Resistance
Colour loss and overall deterioration of paint film on fresh masonry.
- The coating was applied to new masonry that has not cured for a full year. Fresh masonry is likely to contain lime, which is very alkaline. Until the lime has a chance to react with carbon dioxide from the air, the alkalinity of the masonry remains so high that it can attack the integrity of the paint film.
Allow masonry surfaces to cure for at least 30 days, and ideally for a full year, before painting. If this is not possible, apply a quality, alkali-‐resistant sealer or water-‐based primer, followed by a top quality 100 per cent acrylic exterior paint. The acrylic binder in these paints resists alkali attack.
Poor Gloss Retention
Deterioration of the paint film, resulting in excessive, or rapid loss of lustre of the topcoat.
- Use of an interior paint outdoors.
- Use of lower quality paint.
- Use of solvent-‐based paint in areas of direct sunlight.
Direct sunshine can degrade the binder and pigment of a paint, causing it to chalk and lose its gloss. While all types of paint will lose some degree of lustre over time, lower quality paints will generally lose gloss much earlier than better grades. The binder in top quality acrylic latex paint is especially resistant to UV radiation, while solvent-‐based binders actually absorb the radiation, causing the binders to break down. Surface preparation for a coating showing poor gloss retention should be similar to that used in chalking surfaces (see Chalking).
The concentration of water-soluble ingredients on water-‐based paint, creating a blotchy, sometimes glossy appearance, often with a tan or brownish cast. More likely with tinted paints than with white or factory-‐coloured paints.
Painting in cool, humid conditions or just before they occur. The longer drying time allows the paint's water-‐soluble ingredients -‐ which would normally evaporate, or be leached out by rain or dew -‐ to rise to the surface before paint thoroughly dries.
Contact of mist, dew or other moisture with the painted surface shortly after it has dried.
Avoid painting in the late afternoon if cool, damp conditions are expected in the evening or overnight. If the problem occurs in the first day or so after the paint is applied, the water-‐soluble material can sometimes be rinsed off rather easily. Fortunately, even more, stubborn cases will generally weather off in a month or so. Surfactant leaching should not affect the ultimate durability of the coating.
Brownish or tan discolouration on the paint surface due to migration of tannins from the substrate through the paint film. Typically occurs on 'staining timbers,' such as redwood, cedar and mahogany, or over painted knots in certain other timer species.
Failure to adequately prime and seal the surface before applying the paint.
Use of a primer that is not sufficiently stain-‐resistant.
Excess moisture escaping through the exterior walls, which can carry the stain to the paint surface.
Correct any possible sources of excess moisture (see Efflorescence and Mottling). After thoroughly cleaning the surface, apply a high quality stain-resistant solvent-based or water-based primer. Solvent-‐based stain-‐resistant primers are the best type to use on severely staining boards. In extreme cases, a second coat of primer can be applied after the first has dried thoroughly. Finish with a top-quality water-based paint.
A rough, crinkled paint surface occurring when paint forms a 'skin.'
Paint applied too thickly (more likely when using solvent-‐based paints).
Painting a hot surface or in very hot weather.
Exposure of uncured paint to rain, dew, fog or high humidity levels.
Applying the topcoat to the insufficiently dried first coat.
Painting over contaminated surface (e.g., dirt or wax).
Scrape or sand substrate to remove wrinkled coating. Repaint, applying an even coat of top quality exterior paint. Make sure the first coat of primer is dry before applying the topcoat. Apply paints at the manufacturer's recommended spread rate (two coats at the recommended spread rate are better than one thick coat). When painting during extremely humid, cool or damp weather, allow extra time for the paint to dry completely.
Interior Paint Problems
Undesirable sticking together of two painted surfaces when pressed together (e.g., a door sticking to the jamb).
- Not allowing sufficient dry time for the coating before closing doors or windows. Use of low-quality semi-gloss or gloss paints.
Use a premium semi-‐gloss or gloss acrylic enamel paint. Low-quality semi-gloss and gloss water-‐ based paints can have poor block resistance, especially in warm, damp conditions. Follow paint label instructions regarding dry times. Acrylic enamel paints have better early block resistance than vinyl latex paints or solvent-‐based enamel paints. Application of talcum powder can relieve persistent blocking.
- Change in the gloss of the paint film when subjected to rubbing, scrubbing or having an object brush up against it.
- Possible Cause
- Use of flat paint in highly trafficked areas, where a higher sheen level would be desirable.
- Frequent washing and spot cleaning.
- Objects (furniture, for example) rubbing against the walls.
- Use of lower grades of paint with poor stain and scrub resistance (see Poor Stain Resistance and Poor Scrub Resistance).
Paint heavy wear areas that require regular cleaning (e.g., doors, window sills and trim) with a premium semi-gloss or gloss acrylic enamel. This type of paint offers both durability and easier cleaning capability. In high traffic areas, choose a low sheen, semi-‐gloss or gloss rather than a flat sheen level. Clean painted surfaces with a soft damp cloth or sponge and non-‐abrasive cleansers; rinse with clean water.
The splitting of a dry paint film through at least one coat as a result of aging, which ultimately will lead to complete failure of the paint. In its early stages, the problem appears as hairline cracks; in its later stages, flaking and/or peeling occurs.
- Use of a lower quality paint that has inadequate adhesion and flexibility.
- Over thinning or overspreading the paint.
- Inadequate surface preparation, e.g. not applying a sealer or primer on porous surfaces prior to top coating.
- Poor adhesion of the underlying coats.
- Excessive hardening and embrittlement of alkyd paint as the paint job ages.
Remove all loose and flaking paint with a scraper or wire brush, sand the surface and feather the edges. If the flaking occurs in multiple layers of paint, use of a filler may be necessary. Prime bare timber areas before repainting. Use of a premium quality primer and topcoat should prevent a recurrence of the problem.
Formation of bubbles (foaming) and resulting small, round concave depressions (cratering) when bubbles break in a paint film, during paint application and drying.
- Shaking a partially filled can of paint.
- Use of low-quality paint or very old latex paint.
- Applying (especially rolling) paint too rapidly.
- Use of a roller cover with wrong nap length.
- Excessive rolling or brushing of the paint.
- Applying a gloss or semi-‐gloss paint with a long nap roller.
All paints will foam to some degree during application; however, higher quality paints are formulated so the bubbles break while the paint is still wet, allowing for good flow and appearance. Avoid excessive rolling or brushing of the paint or using paint that is more than a year old. Apply gloss and semi-‐gloss paints with a short nap roller.
The appearance of a denser colour or increased gloss where wet and dry layers overlap during paint application.
- Failure to maintain a 'wet edge' when painting.
- Use of a low solids 'economy' paint.
Maintain a wet edge when painting by applying paint toward the unpainted area and then back into the just-‐painted surface. This technique (brushing or rolling from 'wet to dry,' rather than vice versa) will produce a smooth, uniform appearance. It is also wise to work in manageable-‐size areas and plan for interruptions at a natural break, such as a window, door or corner. Using a top-quality water-‐based paint makes it easier to avoid lapping problems because higher solids (pigments and binder) content makes lapped areas less noticeable. If the substrate is very porous, it may need a primer/sealer to prevent paint from drying too quickly, reducing wet edge time and therefore making lapped areas noticeable. Solvent-‐based paints generally have superior wet edge properties and therefore less lapping.
Black, grey or brown spots on the painted surface.
- Forms most often on areas that tend to be damp, or receive little or no direct sunlight (e.g., bathrooms, kitchens and laundry rooms).
- Use of flat or matt paints in areas subject to moisture.
- Use of low-quality latex paint.
- Failure to prime a bare wood surface before applying the paint.
- Painting over a substrate or coating on which mildew has not been removed.
Test for mildew by applying a few drops of household bleach to the area; if it is bleached away, the discolouration is probably mildew. Remove all mildew from the surface by scrubbing with a diluted household bleach solution (one-part bleach, three parts water), while wearing rubber gloves and eye protection. Rinse thoroughly. To protect against mildew, use a premium quality water-‐based paint, and clean when necessary with bleach/ detergent solution. Consider installing an exhaust fan in high moisture areas
Deep, irregular cracks resembling dried mud in dry paint film.
- Paint is applied too thickly, usually over a porous surface.
- Paint is applied too thickly, to improve inherent poor hiding (coverage) of lower quality paint.
- Paint is allowed to build up in corners upon application.
Remove coating by scraping and sanding. Prime and repaint, with a premium water-‐based paint, and a roller with appropriate nap length. Sanding the surface smooth before repainting with a premium water-‐based paint can also repair mud-‐cracked areas. Premium quality paints have a higher solids content, which reduces the tendency to mud crack. They also have very good application and hiding properties, which minimises the tendency to apply the paint too thickly.
An effect of non-‐uniform colour, or sheen level, that can appear when a wall is painted with a roller but is brushed at the edges and corners. The brushed areas generally appear darker, resembling the 'frame' of a 'picture.' Also, sprayed areas may be darker than neighbouring sections that are brushed or rolled.
- Usually a hiding (coverage) effect. Brushing will generally result in lower spread rates than rolling, producing a thicker film and more hiding.
- Adding colourant to a non-‐tintable paint, or using the wrong type, or level, of colourant.
Make sure that spread rates with brushes and rollers are similar. Don't cut in the entire room before roller coating. Work in smaller sections of the room to maintain a 'wet edge.' With tinted paints, be sure the correct colourant-‐base combinations are used. Factory colours, as well as in-‐store tints, should be thoroughly shaken at time of sale, and the product must be thoroughly stirred prior to use.
Failure of paint to dry to a smooth film, resulting in unsightly brush and roller marks after the paint dries.
- Use of lower quality paint.
- Application of additional paint to 'touch up' partially dried painted areas.
- Re-‐brushing or re-‐rolling partially dried painted areas.
- Use of the wrong type of roller cover or poor quality brush.
Use premium quality water-‐based paints, which are generally formulated with ingredients that enhance paint flow. Brush and roller marks thus tend to 'flow out' and form a smooth film. When using a roller, be sure to use a cover with the recommended nap length for the type of paint being used. Use of a high quality brush is important; a poor brush can result in bad flow and levelling.
Failure of dried paint to obscure or 'hide' the surface to which it is applied.
- Use of low-quality paint.
- Use of low-quality tools/wrong roller cover.
- Use of an improper combination of tinting base and tinting colour.
- Poor flow and levelling (see Poor Flow/Leveling).
- Use of a paint that is much lighter in colour than the substrate, or that primarily contains low-‐ hiding organic pigments.
- Application of paint at a higher spread rate than recommended.
If the substrate is significantly darker or is a patterned wallpaper, it should be primed before applying a top coat. Use a premium quality paint for better hiding and flow. Use quality tools; use the recommended roller nap, if rolling. Follow manufacturer's recommendation on spread rate; if using tinted paint, use the correct tinting base. Where a low-‐hiding organic colour must be used, apply a primer first.
Poor Scrub Resistance
Wearing away or removal of the paint film when scrubbed with a brush, sponge, or cloth.
- Choosing the wrong sheen for the area.
- Use of a lower quality paint.
- Use of an overly aggressive scrub medium (see also Burnishing).
- Inadequate dry time allowed after application of the paint before washing it.
Areas that need frequent cleaning require a highly washable premium quality paint formulated to provide such performance. High traffic areas may require a low sheen, semi-‐gloss or gloss paint rather than a flat paint to provide good scrub resistance. Allow adequate dry time, as scrub resistance will not fully develop until the paint is thoroughly cured. Typically, this will be one week. Try washing the painted surface with the least abrasive material and mildest detergent first.
Poor Sheen Uniformity
Shiny spots or dull spots (also known as 'flashing') on a painted surface; uneven gloss.
- Uneven spread rate.
- Failure to properly prime a porous surface, or surface with varying degrees of porosity.
- Poor application resulting in lapping (see Lapping).
New substrates should be primed/ sealed before applying the topcoat to ensure a uniformly porous surface. Without the use of a primer or sealer, an extra coat of paint will more likely be needed. Make sure to apply paint from 'wet to dry' to prevent lapping. Often, applying an additional coat will even out sheen irregularities.
Poor Stain Resistance
Failure of the paint to resist the absorption of dirt and stains.
- Use of lower quality paint that is porous in nature.
- Application of paint to unprimed substrate.
Higher quality water-based paints contain binders that have been formulated to help prevent stains from penetrating the painted surface, allowing for easy removal. Priming new surfaces reduce porosity, and therefore, ensures maximum film thickness of a premium top coat, providing very good stain removability.
The unintentional textured pattern left in the paint by the roller.
- Use of incorrect roller cover.
- Use of lower grades of paint.
- Use of low-quality roller.
- Use of incorrect rolling technique.
Use the proper roller cover; avoid too long a nap for the paint and the substrate. Use quality rollers to ensure adequate film thickness and uniformity. High-quality paints tend to roll on more evenly due to their higher solids content and levelling properties. Use water to pre-‐dampen roller covers to be used with water-‐based paint; shake out excess water. Don't let paint build up at roller ends. Begin rolling at a corner near the ceiling and work down the wall in three-‐foot square sections. Spread the paint in a zigzag 'M' or 'W' pattern, beginning with an upward stroke to minimise spatter; then, without lifting the roller from the surface, fill in the zigzag pattern with even, parallel strokes.
The tendency of a roller to throw off small droplets of paint during application.
- Incorrect rolling technique; applying paint too rapidly
- Use of a low-quality roller or incorrect roller cover.
- Use of lower grades paints.
Higher quality paints are formulated to minimize spattering. Using high-quality rollers, with the appropriate nap length, can help. Overloading the roller with paint will result in excess spatter, as will overworking the paint once it is applied to a substrate. Working in three-‐feet square sections, applying the paint in a zigzag 'M' or 'W' pattern, and then filling in the pattern, will also lessen the likelihood of spattering.
Downward "drooping" movement of the paint film immediately after application, resulting in an uneven coating.
- Application of a heavy coat of paint.
- Application in excessively humid and/or cool conditions.
- Application of over-‐thinned paint.
- Airless spraying with the gun too close to the substrate being painted.
If the paint is still wet, immediately brush out or re-‐roll to redistribute the excess evenly. If the paint has dried, sand and reapply a new coat of top quality paint. Correct any unfavourable conditions: Do not thin the paint; avoid cool or humid conditions; sand glossy surfaces. Paint should be applied at its recommended spread rate; avoid 'heaping on' the paint. Two coats of paint at the recommended spread rate are better than one heavy coat, which can also lead to sagging. Consider removing doors to paint them supported horizontally.
The concentration of water-soluble ingredients on water-based paint, creating a blotchy, sometimes glossy appearance, often with a tan or brownish cast. More likely with tinted paints than with white or factory-coloured paints.
- Painting in cool, humid conditions or just before they occur. The longer drying time allows the paint's water-soluble ingredients — which would normally evaporate, to rise to the surface before paint thoroughly dries.
- Exposure to steam or condensation before adequate curing time can also lead to this issue.
Ensure the temperature in the room is above 10 degrees while painting and during the curing time. Keep airflow up during the drying phase with fan heaters and open windows. Do not expose the paint to condensation for 48 hours after painting. If the problem occurs the water-‐soluble material can be washed off with a mild detergent and water but should be done as soon as it is noticed. Surfactant leaching should not affect the ultimate durability of the coating.
A rough, crinkled paint surface, which occurs when uncured paint forms a 'skin.'
- Paint applied too thickly (more likely when using alkyd or oil-‐based paints).
- Painting during extremely hot weather or cool damp weather, which causes the paint film to dry faster on top than on the bottom.
- Exposing uncured paint to high humidity levels.
- Applying a top coat of paint to the insufficiently cured primer.
- Painting over contaminated surface (e.g., dirt or wax).
Scrape or sand substrate to remove wrinkled coating. If using a primer, allow it to dry completely before applying topcoat. Repaint (avoiding temperature/ humidity extremes), applying an even coat of top quality interior paint.
Development of a yellow cast in ageing paint solvent-‐based enamels; most noticeable in the dried films of white paints or clear varnishes.
- Oxidation of alkyd or oil-‐based paint or varnish.
- The heat from stoves, radiators and heating ducts.
- Lack of light (e.g., behind pictures or appliances, inside closets, etc.).
Top-quality water-‐based paints do not tend to yellow, nor does non-‐yellowing varnish. Solvent-‐based paints, because of their curing mechanism, do tend to yellow, particularly in areas that are protected from sunlight. To prevent yellowing, use a premium quality water-‐based paint in place of solvent-‐ based paint