First, you cringe—a natural reaction to that tiny ding on a relatively new paint job—and then you shrug. Some paint imperfections, however, are more conspicuous and harder to overlook. Such issues must be addressed, the sooner the better, not only to restore the painted surface but to investigate potential underlying problems.
Read on to understand the causes of common paint problems and how to repair them and avoid future issues.
Cracking, Flaking, and Clumping
Vein-like lines that appear through at least one coat of paint may be faint initially, but these cracks tend to grow and deepen into dry, jagged flakes. Such unsightliness can strike a variety of surfaces, indoors and out, from plaster to wood and siding.
What causes paint to crack?
Insufficient surface prep is the main culprit behind crack attacks. Over-thinning your paint or applying it too thinly can also cause it to split.
Conversely, a heavy hand while painting can lead to what’s called mud cracks, where too-thick paint dries with a clumpy, swollen look. Not allowing adequate dry time between coats can also lead to these problems. And unfortunately, cracks can appear simply due to age. Over time, paint becomes brittle, making it less adaptable to temperature and humidity fluctuations.
Repair and Prevention
If damage is extensive, you may need to repaint the entire surface. If not, with the right technique, you can repair a poorly painted spot without a lot of headache. Follow the tips detailed below for solutions.
- Remove all cracked and flaking paint with a scraper, wire brush, heat gun, or chemical application (depending on the extent and severity of the problem).
- Sand, feathering the edges to blend, then clean and prime the surface.
- Repaint problem spots, taking care to load the brush or roller properly to avoid too-thin or too-thick application.
- For brush application, dip the brush in, allowing paint to cover up to one-third of the bristle length; tap the brush lightly on both sides and avoid dragging the brush against the edge of the container.
- If using a roller, fill the roller tray halfway. Remove lint from a new roller cover, dip the roller into the well of the tray, then over the ribbed portion of the tray, repeating several times to evenly distribute the right amount of paint.
To avoid heavy buildup in corners where paint commonly overlaps, thoroughly feather out the cut-in area; then clean and prep, reapplying paint evenly. And be patient, always remembering to let paint dry fully between coats. When repainting to repair, you’ll likely want to apply the same product you used initially (but in subsequent projects, opt for quality latex paint, known for its adhesion and flexibility).
Peeling
Peeling paint that has a bit of curl to it is a common problem on both interior and exterior surfaces.
What causes paint to peel?
While improper prep and application can contribute to peeling, moisture is public enemy number one.
- Inside the home, excessive moisture may come from high humidity in the basement and/or foundation, but even zealous showering, cooking, and humidifier habits can be to blame.
- Outside the house, peeling can result from inadequate caulking, clogged gutters, a leaky roof, or interior moisture that seeps through exterior walls. Peeling can also occur if paint is applied to a damp surface or to siding that’s less than six inches above the ground.
Repair and Prevention
Watch: Repairing Peeling Paint
Create a less peel-prone environment inside and out by implementing the following recommendations.
Improve interior ventilation as needed with exhaust fans, wall vents, and/or louvers.
For exterior conditions such as crumbly caulking, full gutters, or loose shingles, remove peeling paint by sanding, cleaning, and priming before repainting.
Blistering a.k.a. Bubbling
Paint film fails to properly adhere and lifts off the surface in the form of multiple rounded bumps. Blisters can appear on both interior and exterior painted surfaces—drywall, plaster, metal, and wood.
What causes paint to blister or bubble?
Heat and moisture are both blister gremlins. Painting in direct, intense sunlight or on overly hot surfaces can cause heat bubbles on exteriors; newly dried latex paint that’s exposed to dew, rain, or high humidity may also blister.
On interiors, moisture passing through the walls from bathrooms, kitchens, basements, and laundry rooms can push paint off the surface. Oil-based paint is also apt to blister when applied over a damp surface—or when applied over water-based (latex) paint. Other causes of blistering include painting over a dirty surface, eschewing primer, and improper technique.
Repair and Prevention
Burst a few bubbles and examine the backside of blistered paint, as well as the substrate if it becomes exposed, to determine if moisture or heat is the culprit.
- If the blisters contain several coats of paint and popping them reveals bare substrate, there’s a moisture issue. Address this by repairing plumbing, replacing caulking, and/or increasing ventilation as required. Then remove all blistered paint, sand smooth, clean, prime, and repaint.
- If blisters affect only the previous coat of paint, heat is likely at fault. Remove blisters and the underlying paint or primer, then sand to smooth and dull the surface, clean, prime, and repaint, taking care that the surface is below 90º F.
- Stir paint slowly yet briefly with a wooden stirrer or drill attachment. Stirring too quickly or for too long can introduce bubbles to the paint that could transfer to the surface.
- Be patient when rolling. If you detect bubbles during application, slow your stroke speed.
- Ideally, stick to one formula to avoid blistering: latex over latex and oil over oil. While it’s possible to successfully apply latex paint over oil-based primers and paints if necessary, you should try to avoid doing so as it’s likely to lead to blistering.
Efflorescence
Crusty white salt crystals may look appealing on a pretzel, but not on the painted masonry of your home. Efflorescence (also known as mottling) appears when the salts inherent in brick, concrete, cinderblock, and mortar dissolve in moisture and then leach out to the surface.
What causes efflorescence?
A variety of factors contribute to efflorescence, including:
- insufficient curing time for cement or mortar during construction;
- moisture migration from inside the house;
- groundwater penetration from an inadequately waterproofed basement;
- insufficient surface prep to remove previous efflorescence; and
- painting over holes, cracks, or unrepaired pointing.
Repair and Prevention
Tackle efflorescence on a warm, dry day. Eliminate excess moisture conditions externally by waterproofing and repairing cracks, repointing, and sealing around windows and doors with butyl rubber caulk.
There are various ways to remove efflorescence, and you may need to use a combination, depending on the extent and severity: a wire brush, scraper, low-pressure washer, and/or cleaning with diluted white vinegar or a trisodium phosphate (TSP) solution (wear protective gear when working with this chemical) and then rinsing thoroughly.
Applying an impregnating hydrophobic sealant to a building material surface can prevent water absorption and keep moisture from entering the material. Colorless water repellents may prevent efflorescence from recurring, as may silicone or acrylic coatings. Allow to dry completely before repainting.
Alligatoring
Perhaps the most creative term for a paint problem, alligatoring refers to a pattern that really does resemble reptilian skin. It starts as subtle wrinkling (a.k.a. checking), then develops into wide rectangular cracks. Alligatoring tends to be more common with oil-based paints.
What causes alligatoring?
Paint naturally expands and contracts in response to temperature fluctuations and, over time, loss of elasticity can result in alligatoring.
The process can be hastened through such missteps as applying a rigid coating such as oil enamel over a softer, more flexible coat (e.g., latex paint or latex primer); painting over a glossy finish (the topcoat not bonding properly to the glossy finish), or not allowing sufficient dry time between primer/basecoat and topcoat.
Repair and Prevention
- Remove unsightly scales by scraping, sanding, applying chemical removers, or using a heat gun.
- Then rinse to banish dust and let dry completely. Prime, allow to dry and repaint.
Chalking
A fine, powdery white substance that forms on painted exteriors, chalking is most often seen in arid, sunny climates. It tends to be most visible on pale-colored flat paints and is likely to occur on improperly sealed porous materials and poor-quality, factory-finished aluminum siding.
What causes paint to chalk?
The pigments in paint are naturally released when exposed to weather changes, so some chalking is to be expected over time. But serious cases are usually due to using the wrong product—either interior paint or low-quality exterior paint that contains a high degree of extenders (white, powdery paint additives). Over-thinning paint prior to application can also lead to chalking.
Repair and Prevention
- Eliminate all evidence of chalking by power washing or treating with TSP solution, then rinsing.
- Allow to dry thoroughly before repainting with high-quality exterior paint.
