Exterior Paint Solution Center

• Failure to adequately prepare 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 a high quality, 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 and allow it to dry completely; then apply a coat of top quality exterior house paint, masonry paint or elastomeric wall coating.

• Use of an interior paint for an out door application.
• Use of a low quality paint, leading to rapid degradation (chalking) of the paint film. Blues appear to fade, but are actually chalking.
• Use of custom paint colors that are vulnerable to UV radiation, most notably, lighter reds, yellows, and oranges.
• Tinting a coating not intended for tinting, or over tinting a light or medium paint base.

• When fading/poor color retention is a result of chalking, it is necessary to remove as much of the chalk as possible (see Chalking). Avoid custom colors using colorants that are not suited for exterior use. Ready-made colors made with inorganic oxide pigments are the most colorfast. In repainting, be sure to use a high quality latex exterior house paint in colors recommended for exterior use.

Frosting

• Forms mostly in protected areas (such as under eaves and open porch ceilings) that do not receive the cleansing action of rain, dew and other moisture.
• Use of Japan drier or other accelerators with dark colored oil and alkyd based paints.
• Application of dark-colored paint over a paint or primer containing calcium carbonate extender pigments.
   

• Frosting can be a stubborn problem. It often cannot be washed off readily. Moreover, the condition can recur even as a bleed-through when a new topcoat is applied. In extreme cases, it can interfere with adhesion. The best remedy is to remove the frosting by wire brushing masonry or sanding wood surfaces; rinse, and then apply an alkyd-based primer before adding a coat of high quality exterior paint.

Lapping

• Failure to maintain a “wet edge” when applying paint.
• Failure to use a primer over a porous surface.
   

• When painting, maintain a wet edge by applying the paint starting from the unpainted area and going back into the just-painted area. This technique (brushing from “dry to wet”, rather than vice versa) will help produce a smooth, uniform appearance. It is also wise to work in manageable-size areas; plan for job interruptions at natural breaks, such as a window, door or corner. This is especially important when applying stain to bare wood. If the substrate is very porous, a primer/sealer should be used to provide an optimal surface that will prevent the topcoat from drying too quickly and reducing the wet edge time. Alkyd paints generally have superior wet edge properties.

• Forms mostly on areas that tend to stay damp, and receive little or no direct sun light. Walls with a northerly exposure and the underside of eaves are particularly vulnerable to mildew growth.
• Use of a lower quality paint, which has an insufficient amount of mildewcide.
• Painting over a substrate or coating on which the mildew has not been removed.

• Test for mildew by applying a few drops of household bleach to the discolored area; if the stain lightens in color or disappears, it is 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 with clean water, prime any bare wood, and then apply one or two coats of high quality exterior paint, which typically contains the correct amount of mildewcide.

Nailhead Rusting

• Non-galvanized iron nails have begun to rust, causing bleed-through to the topcoat.
• Non-galvanized iron nails have not been countersunk, primed, and filled.
• 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 nailheads, spot prime, then caulk with a high quality, all-acrylic or paintable siliconized 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 nailheads, arid then follow the same surface preparation procedures as outlined above.