Common Paint Defects
Gelling
Decreasing viscosity caused by bacterial degradation of the protein binder or other thickening agents. This is often accompanied by an offensive odour.CAUSES:Use of contaminated tools and water/solvents.Mixing of different brands or types of paints.SOLUTION:Use clean tools and water/solvents.Avoid mixing different brands or types of paints.
Skinning
Formation of a layer of skin on the surface of the paint or the container.CAUSES:Use of non-airtight containerLack of anti-skinning agentStorage under excessively warm conditionSOLUTION:Use airtight containerAvoid unnecessary opening of canStore as recommended by manufacturerRemove the layer of skin and stir paint to homogeneous consistency
Settling
Settlement of pigment to the bottom and failure to re-disperse. CAUSES: Insufficient stirring during storage. Storage for long duration or under excessively warm condition. Excessive dilution or dilution with unsuitable materials. SOLUTION: Store as recommended by manufacturer. Avoid direct sunlight and long storage. Dilute with appropriate thinners as recommended by manufacturer. Stir paint to a homogeneous consistency. Employ mechanical stirring for heavy settling.
Prolonged Tackiness
A coat of paint is dry when it ceases to be "tacky" to the touch. Prolonged tackiness indicates excessively slow drying. This may be caused by insufficient drier in the paint, a low-quality vehicle in the paint, applying the paint too thickly, painting over an undercoat that is not thoroughly dry, painting over a waxy, oily, or greasy surface, or painting in damp weather.Possible Causes:Paint has inadequate adhesion and flexibility.Overthinning or overspreading the paint.Inadequate surface preparation or applying the paint to bare wood without first applying a primer.Excessive hardening and embrittlement of alkyd-based paints as the paint job ages.Solution:Remove loose and flaking paint with a scraper or wire brush, sanding the surface and feathering the edges. If the flaking occurs in multiple layers of paint, use of fillers may be necessary. Prime bare wood areas before repainting
Rising Damp
Rising damp actually describes the movement of moisture upward through permeable building materials by capillary action. It becomes a problem if the moisture penetrates vulnerable materials or finishes, particularly in the occupied parts of a building.Possible Causes:Masonry structure, unprotected by a properly installed damp-proof course, is susceptible to natural rising damp.Faulty guttering or missing ventilation causing ice dams or water back up.Painting when the surface being painted is wet from condensation or rain.Solution:Ensure proper drainage of gutters and downspouts flowing away from home.Eliminate cause or source of moisture by installing exhaust fans, soffit vents, siding vents, louvers, fans, and dehumidifiers.Repair and replace missing or damaged caulk.Scrape away old peeling paint and feather sand affected areas.Spot prime and paint with Moisture resistant Sealer / Paint.
Foaming / Cratering
Formation of bubbles or foam and resulting small, round concave depressions. When bubbles break in a paint film, during paint application and drying.Possible Causes:Shaking a partially filled can of paint.Using low-quality latex paint, or paint that is old.Applying (especially rolling) paint too rapidly.Using a roller cover with the wrong nap length.Excessively rolling or brushing the paint.Applying a gloss or semi-gloss paint over a painted surface without first priming.Solution:Avoid excessive rolling or brushing.Avoid using paint that is more than a year old.Prime porous surfaces before applying paint.If applying gloss or semi-gloss paints, prime before painting and use a short nap roller.Avoid vigorous shaking of the paint can or swirling the brush in the paint.Sand problem areas before repainting.
Improper Induction of Epoxy
Epoxy is a two-part system, consisting of a Base and converter. Improper Induction will result in difference in color, soft film, peeling, difference in gloss, poor coverage etc.Possible Cause:Improper mixing of the Base and Converter.The induction time was inadequate.The mixing ration was incorrect.Solution:1.Mix the Base and Converter and allow to induct as recommended by the manufacturer.2. Constantly stir paint during application.
Mud Cracking
Deep, irregular cracks resemble dried mud in dry paint film.Possible Cause:Paint is applied too thickly, usually over a porous surface.Paint applied too thick, to improve hiding.Paint is allowed to build up in corners upon application.Solution:Mud cracking areas can be repaired by sanding the surface smooth, then prime, and repaint.Use high quality Latex paints as it has more flexibility than alkyd paints.
Fungal Growth
Fungus growth can appear with high humidity of surroundings or damp substrate or high moisture content. Fungus is commonly found on internal wall surfaces of damp areas in the absence of sun light.Possible Cause:Condensation on surface.Over coating a fungus infected substrate.Poor ventilationSolutions:Seal and Waterproof the surface.Remove dirt and fungus by High Pressure Water Jetting.Treat infected area with fungicidal wash or diluted bleach.Allow the surface to dry then repaint it with a Fungus Resistant Paint.
Algal Growth
The coating surface shows a green growth, usually on north facing timbers.Possible Cause:Plants, bushes and trees in close proximity to coating system.High humidity of surroundings and/or moisture content of substrateSolution:Remove/kill algae/moulds and clean substrate.Treat with a fungicidal (or diluted bleach) solution.Scrub dead spores loose, rinse clean and allow to dry fully. Where necessary, redecorate with suitable coating.
Saponification
Alkyd and oil-based paints react and saponify with alkalis present in new masonry to form water-soluble soaps. The paint film turned into soap, becomes soft, sticky, and water-soluble.Possible Cause:Incorrect use of productApplication of Alkyd-based (oil) paints to alkaline material (e.g. concrete or cement.)Humidity problems.Caustic stripped surface not neutralized.Solution:Remove all paint layers.Prevent water penetration.Apply an alkali resistant coating.
Poor Galvanized Metal Adhesion
Paint that has lost its adhesion to a galvanised metal substrate. Possible Cause: Improper surface preparation, such as inedquate rust removal. Failure to remove the oil coating in the metal before repainting. Failure to apply a primer before application. Failure to sand glossy surface before painting. Solution: Any rust on the metal should be removed by wirebrush or by using a rust remover. Clean the Galvanised metal with mineral spirits to take of the oil coating, allow it to dry and paint with a corrosion resistant primer.
Chalking
Formation of fine powder on the surface of the 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. Possible Cause: Use of an interior paint for exterior application. Over thinnning of paint. Not properly sealing a porous surface before painting. Solution: Remove as much of the chalk residue as possible, using a stiff bristle brush and rinse throughly with a garden hose; or use power washing equipment. Check for any remaining chalk by running a hand over the surface after it dries. Apply a quality primer before repainting.
Efflorescence / Mootling
Crusty white salt deposits, leached from martor or masonry as water passes through it. Possible Cause: Painting over insufficiently cured concrete. Excess moisture escaping through the exterior masonry wall from inside. Failure to adequately prepare surface by removing all previous efflorescence. Solution: If excess moisture is the cause, eliminate the source by repairing. Seal any cracks in the masonry. Remove the effloresence and all loose material with wire brush, power brush or power washer; then thoroughly rinse the surface. Seal off with compatible alkali resisting primer before painting. When efflorescence proceeds to the calcium carbonate phase, it becomes insoluble and is more difficult to remove-Perhaps impossible. The application of a mild acid solution becomes the first course of action. These acids include vinegar (5%Acetic Acid), Muriatic acid or citric acid.
Paint Incompatibility
Loss of adhesion where many old coats of alkyd or oil base paint received a latex top coat. Possible Cause: Use of water base latex paint over more than three of four coats of old alkyd or oil base paint may cause the old paint to “ lift off” the substrate. Solution: Completely remove the existing paint and prepare surface cleaning, sanding and spot priming where necessary before repainting .
Sagging
Downward “dropping” movement of the paint film immediately after application resulting in an uneven coating. Possible Cause: Application of a heavy coat of paint. Application in excessively humid an/or cool condition. Application of overthinned paint. Airless spraying with the gun too close the substrate being painted. Application of Gloss paint on existing paints or surface without sanding. Solution: If paint is still wet, immediately brush out or re roll to redistribute the excess evenly. If the paint has dried, sand an reapply a new coat of paint. Correct any unfavorable conditions: Do not thin the paint; avoid cool or humid condition; Sand glossy surface. Paint should be applied at its recommended spread rate; avoid heaping on the paint . Two coats of paint at is recommended spread rate is better than one heavy coat.
Peeling
Loss of paint due to poor adhesion. Where there is a primer and top coat, or multiple coats of paint, peeling may involve some or all coats. Possible Cause: Seepage of, moisture through open joints, worn caulk or leaks in roof of walls. Excessive moisture escaping through the exterior walls. Inadequate surface preparation. Applying oil base paint over wet surface. Solution: Try to identify and eliminate causes for moisture. Prepare surface by removing all loose paint with scraper or wire brush, sand rough surface, prime bare wood. Repaint.
Blistering
Bubbles resulting from localized loss of adhesion and lifting of the paint film from the underlying surface. Possible Causes: Painting a warm surface in direct sunlight. Application of oil- base or alkyd paint over a damp or wet surface. Moisture escaping through the exterior walls. Exposure of latex paint film to dew, high humidity or rain shortly after paint has dried, especially if there was inadequate surface preparation. Solution: If blisters go down to substrate, try to remove the source of moisture. Repair loose caulking; consider installing an exhaust fan. If blisters do not go all the way down to the substrate, remove them by scraping, sanding; prime bare wood and repaint.
Cracking/Flaking
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 hair line cracks; in its later stages, flaking occurs. Possible Causes: Use paint that’s has inadequate adhesion and flexibility. Overthinning or overspreading the paint. Inadequate surface preparation or applying the paint to bare wood without first applying a primer. Excessive hardening and embrittlement of alkyds paints as the paint jobs ages. Solution: Remove loose and flaking paint with a scraper or wire brush, sanding the surface and feathering the edges. If the flaking occurs in multiple layers of paint, use of fillers may be necessary. Prime bare wood areas before repainting.
Gelling
Decreasing viscosity caused by bacterial degradation of the protein binder or other thickening agents. This is often accompanied by an offensive odour. CAUSES: Use of
Skinning
Formation of a layer of skin on the surface of the paint or the container. CAUSES: Use of non-airtight containerLack of anti-skinning agentStorage under excessively
Settling
Settlement of pigment to the bottom and failure to re-disperse. CAUSES: Insufficient stirring during storage. Storage for long duration or under excessively warm condition. Excessive
Prolonged Tackiness
A coat of paint is dry when it ceases to be “tacky” to the touch. Prolonged tackiness indicates excessively slow drying. This may be caused
Rising Damp
Rising damp actually describes the movement of moisture upward through permeable building materials by capillary action. It becomes a problem if the moisture penetrates vulnerable
Foaming / Cratering
Formation of bubbles or foam and resulting small, round concave depressions. When bubbles break in a paint film, during paint application and drying. Possible Causes:
Improper Induction of Epoxy
Epoxy is a two-part system, consisting of a Base and converter. Improper Induction will result in difference in color, soft film, peeling, difference in gloss,
Mud Cracking
Deep, irregular cracks resemble dried mud in dry paint film. Possible Cause: Paint is applied too thickly, usually over a porous surface. Paint applied too
Fungal Growth
Fungus growth can appear with high humidity of surroundings or damp substrate or high moisture content. Fungus is commonly found on internal wall surfaces of
Algal Growth
The coating surface shows a green growth, usually on north facing timbers. Possible Cause: Plants, bushes and trees in close proximity to coating system. High
Saponification
Alkyd and oil-based paints react and saponify with alkalis present in new masonry to form water-soluble soaps. The paint film turned into soap, becomes soft,
Poor Galvanized Metal Adhesion
Paint that has lost its adhesion to a galvanised metal substrate. Possible Cause: Improper surface preparation, such as inedquate rust removal. Failure to remove the
Chalking
Formation of fine powder on the surface of the film during weathering, which can cause colour fading. Although some degree of chalking is a normal,
Efflorescence / Mootling
Crusty white salt deposits, leached from martor or masonry as water passes through it. Possible Cause: Painting over insufficiently cured concrete. Excess moisture escaping through
Paint Incompatibility
Loss of adhesion where many old coats of alkyd or oil base paint received a latex top coat. Possible Cause: Use of water base latex
Sagging
Downward “dropping” movement of the paint film immediately after application resulting in an uneven coating. Possible Cause: Application of a heavy coat of paint. Application
Peeling
Loss of paint due to poor adhesion. Where there is a primer and top coat, or multiple coats of paint, peeling may involve some or
Blistering
Bubbles resulting from localized loss of adhesion and lifting of the paint film from the underlying surface. Possible Causes: Painting a warm surface in direct
Cracking/Flaking
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
