Bubbles resulting from localized loss of adhesion, and lifting of the paint film from the underlying surface.

Blistering

POSSIBLE CAUSES:

• 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.

SOLUTION:

• If blisters go down to the substrate: try to remove the source of moisture. Repair loose caulking; consider installing vents or exhaust fans. Remove blisters (see Below).
• If blisters do not go all the way down to the substrate: remove them by scraping, then sanding, prime bare wood and repaint with a quality latex exterior paint.

Undesirable sticking together of two painted surfaces when pressed together (e.g., a door sticking to the jamb).

Blocking

POSSIBLE CAUSES:

• Not allowing sufficient dry time for the coating before closing doors or windows.
• Use of low quality semigloss or gloss paints

SOLUTION:

• Use top quality semigloss or gloss acrylic latex paint. Low quality latex paints can have poor block resistance, especially in warm, damp conditions. Follow paint label instructions regarding dry times. Acrylic latex paints generally have better early block resistance then vinyl latex paints or alkyd or oil-based paints; however, alkyds develop superior block resistance over time. Application of talcum powder can relieve persistent blocking.

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 occurs.

Cracking / Flaking

POSSIBLE CAUSES:

• Use of lower quality paint that 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 paint 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 a filler may be necessary. Prime bare wood areas before repainting. Use of a top quality primer and top coat should prevent a recurrence of the problem.

Appearance of a denser color or increased gloss where wet and dry layers overlap during paint application.

Lapping

POSSIBLE CAUSES:

• Failure to maintain a "wet edge" when painting.
• Use of a low solids "economy" paint.

SOLUTION:

• 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; plan for interruptions at a natural break, such as a window, door or corner. Using a top quality acrylic latex paint makes it easier to avoid lapping problems because higher solids (pigments and binder) content makes lapped areas less noticeable. If substrate is very porous, it may need a primer/sealer to prevent paint form drying too quickly and reducing wet edge time. Alkyd paints generally have superior wet edge properties.

Black, gray or brown spots or areas on the surface of paint or caulk.

Mildew

POSSIBLE CAUSES:

• 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 an alkyd or oil-based paint, or lower quality latex paint.
• Failure to prime bare wood surface before applying the paint.
• Painting over a substrate or coating on which mildew has not been removed.

SOLUTION:

• Test for mildew by applying a few drops of household bleach to the area; if it is bleached away, the discolorant 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 top quality latex 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.

Mud Cracking

POSSIBLE CAUSES:

• Paint applied too thickly, usually over a porous surface.
• Paint applied too thickly, to improve inherent poor hiding (coverage) of a lower quality paint.
• Paint is allowed to build up in corners upon application.

SOLUTION:

• Remove coating by scraping and sanding. Prime and repaint, using a top quality latex paint. Mud-cracked areas can also be repaired by sanding the surface smooth before repainting with a top quality latex paint. This type of paint is likely to prevent recurrence of mud cracking, because it is relatively more flexible than alkyd paint, oil-based paint and ordinary latex paint. Quality paints have a higher solids content, which reduces the tendency to mud crack. They also have very good application and hiding properties, which minimize the tendency to apply too thick a coat of paint.

An effect of non uniform color that can appear when a wall is painted with a roller, but is brushed at the corners. The brushed areas generally appear darker, resembling the "frame" of a "picture." Also, sprayed areas may be darker than neighboring sections that are brushed or rolled. Picture framing can also refer to sheen effects.

Picture Framing

POSSIBLE CAUSES:

• Usually a hiding (coverage) effect. Brushing will generally result in lower spread rates than rolling, producing a thicker film and more hiding.
• Adding colorant to a non tintable paint or using the wrong type or level of colorant, resulting in variation in color, depending on method of application.

SOLUTION:

• 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 colorant-base combinations are used. Factory colors, as well as in-store tints, should be thoroughly shaken at time of sale.

Failure of dried paint to obscure or "hide" the surface to which it is applied.

Poor Hiding

POSSIBLE CAUSES:

• Use of low quality paint.
• Use of low quality tools/wrong roller cover.
• Use of an improper combination of tinting base and tinting color.
• Poor flow and leveling (see Poor Flow/Leveling).
• Use of a paint that is much lighter in color than the substrate, or that primarily contains low-hiding organic pigments.
• Application of paint at a higher spread rate than recommended.

SOLUTION:

• If the substrate is significantly darker or is a patterned wallpaper, it should be primed before applying a top coat. Use a top 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 color must be used, apply a primer first.

Shiny spots or dull spots (also known as "flashing") on a painted surface; uneven gloss.

Poor Sheen Uniformity

POSSIBLE CAUSES:

• Uneven spread rate.
• Failure to properly prime a porous surface, or surface with varying degrees of porosity.
• Poor application resulting in lapping (see Lapping).

SOLUTION:

• New substrates should be primed/sealed before applying the top coat to ensure a uniformly porous surface. Without the use of a primer or sealer, a second 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.

Concentration of water-soluble ingredients on latex paint, creating a blotchy, sometimes glossy appearance, often with a tan or brownish cast. More likely with tinted paints than with white or factory-colored paints.

Surfactant Leaching

POSSIBLE CAUSES:

• 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.
• Mist, dew or other moisture drying on the painted surface shortly after it has dried.

SOLUTION:

• 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. Sufactant leaching should not affect the ultimate durability of the coating.

Development of a yellow cast in aging paint; most noticeable in the dried films of white paints or clear varnishes.

Yellowing

POSSIBLE CAUSES:

• Oxidation of alkyd or oil-based paint or varnish.
• Heat from stoves, radiators and heating ducts.
• Lack of light (e.g., behind pictures or appliances, inside closets, etc.).

SOLUTION:

• Top quality latex paints do not tend to yellow, nor does non-yellowing varnish. Alkyd paints, because of their curing mechanism, do tend to yellow, particularly in areas that are protected from sunlight.

Crusty, white salt deposits, leached from mortar or masonry as water passes through it.

Efflorescence

POSSIBLE CAUSES:

• Failure to adequately prepare surface by removing all previous efflorescence.
• Excess moisture escaping through the exterior masonry walls from behind.

SOLUTION:

• 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 a high quality, water-based all-acrylic or siliconized 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 or primer, and allow it to dry completely; then apply a coat of top quality exterior house paint, masonry paint or elastomeric wall coating.