Understanding the primary causes of paint failures will help you prevent future paint problems. The primary causes of paint failures are moisture, inadequate surface prep, the improper application of paints, the Sun, and weathering. You should be aware that most paint failures are related to moisture and inadequate surface preparation. Some of the more common paint failures are listed on the next few pages in order of prevalence in Calgary climate with recommendations for their prevention.
Mildew is not a big problem in the Calgary area because of our dry climate. Mildew is a fungus that grows best in a warm humid climate and is often found in shaded areas, but not limited to shaded areas. Mildew can appear in a variety of colors and prefers painted surfaces because of the nutrients that paints provide. These same nutrients float through the air and land on painted surfaces and become food. Mildew grows faster on flat surfaces than on glossy surfaces, and is attracted to linseed oil based products that contain no fungicide. Most paints and stains come already made with fungicide included. However, fungicide can be added to paints and stains that do not contain one. Mildew can be effectively cleaned with a 3 to 1 ratio of water to bleach. A much stronger solution may be necessary in extreme cases of neglect. Proper surface preparation and cleaning are crucial for mildew prevention; in addition to using top quality primer and acrylic latex finish paint. Acrylic latex finish paints are the most mildew resistant. Painting contractors who perform quality surface preparation and painting are a homeowner’s best ally in preventing the growth of mildew.
Chalking is the weathered powder found on exterior painted surfaces and is a normal way for paint to weather away. However, premature chalking can be caused by inadequate priming or thin paint. Homeowners should be aware that chalking on siding located above masonry will run during rainy weather causing the masonry to stain. Once a chalked surfaced is pressured washed clean and prepared for painting, one coat of a top quality alkyd primer and one coat of a top quality acrylic latex finish paint is highly recommended for the prevention of future excess chalking.
Rusting occurs when metal is exposed to moisture and oxygen. Any metal surfaces should be completely sealed with a rust inhibited primer. If rust appears through painted surfaces, it should be wire brushed to bare metal, or treated with a coating that will harden it. Two coats of a top quality rust inhibited alkyd or acrylic latex primer should be applied to metal surfaces once the rust is treated or wire brushed away. Rusty nails that bleed through surfaces should be reset, coated with a top quality rust inhibited primer, caulked, primed, and painted with top quality coatings.
Fading is caused by the natural weathering due to the ultraviolet rays of the Sun. Chalking pigment, alkali from masonry, and tint intended for interior based paints but used on exterior surfaces, will cause paint to fade prematurely. This can be reduced by using any Acrylic instead of Alkyd paint. An acrylic paint is more colour fast than Alkyd paints. Red and other primary colours fade more than earth tones. If customers want let fading encourage these colours.
Efflorescence is a white salty substance that forms on masonry and plaster due to moisture migrating through the surface. If left untreated for long periods of time, it will become hard and crusty. Any source of excessive moisture must be eliminated and the surface must be cleaned by scraping or wire brushing, and surfaces must be repaired where applicable before priming and painting. Surfaces can be painted with top quality alkyd or acrylic latex based primers and paints that are alkaline resistant
Blistering - Fresh paint applied in direct sunlight, and moisture, causes paint to blister. Surfaces that are heated by the Sun and become hot can prematurely dry new paint, causing blistering. This is more common with dark or dramatic colors because they, in addition to surfaces, absorb heat. Heat blistering will have a layer of paint under the blister if the surface is being repainted. Trapped moisture in walls or behind surfaces will eventually try to escape through painted surfaces, also causing blistering. Moisture blistering will reveal a bare surface under the blister. Blistering surfaces should be scraped and sanded smooth, primed with a top quality alkyd or acrylic latex primer, and finished with top quality acrylic latex finish paint. If moisture blistering occurs on a repainted surface, spot priming of bare spots will be necessary to ensure a uniform and even finish before the final priming and painting is completed.
Alligatoring is cracked paint that resembles alligator skin, and is generally found on wood surfaces. Alligatoring occurs when paint cannot adhere to a glossy surface, when a second coat of paint is applied over an inadequately dried first coat of paint, weather aging, excessive coats of paint, or when the finish coat expands and contracts at a greater extent that any underlying coats. Paint must be completely removed when alligatoring has occurred to ensure an even and uniform finish. Wood surfaces should be primed with a top quality alkyd primer and acrylic latex finish. This is extremely expensive and it would probably be cheaper to replace siding.
Bleeding is an unsightly surface discoloration commonly found on exterior wood surfaces and hardboard siding, ceilings, repainted wallpaper, or when light colored paint is applied over dark colored paint. The causes of bleeding are moisture and water soluble dyes located within wood surfaces and wallpaper, and inadequate priming of surfaces. Bleeding on hardboard siding is caused by wax. The removal of any excessive water source is essential before any surface preparation can be completed. Exterior wood surfaces should be primed with top quality alkyd based primers and finished with top quality acrylic latex paints. Interior surfaces should be primed with either a top quality alkyd based or acrylic latex based stain blocking primer, and finished with top quality acrylic latex finish paint. is an unsightly surface discoloration commonly found on exterior wood surfaces and hardboard siding, ceilings, repainted wallpaper, or when light colored paint is applied over dark colored paint. The causes of bleeding are moisture and water soluble dyes located within wood surfaces and wallpaper, and inadequate priming of surfaces. Bleeding on hardboard siding is caused by wax. The removal of any excessive water source is essential before any surface preparation can be completed. Exterior wood surfaces should be primed with top quality alkyd based primers and finished with top quality acrylic latex paints. Interior surfaces should be primed with either a top quality alkyd based or acrylic latex based stain blocking primer, and finished with top quality acrylic latex finish paint.
Peeling occurs on a variety of surfaces and is directly linked to moisture and inadequate surface preparation. Understanding different surfaces and how they react to moisture and coatings will greatly reduce the risk of this common paint problem.The most common areas that peel in Calgary are, decks, window sills, fence tops, galvanized metal.Decks, window sills and fence tops: these are a maintenance item and should be painted every few years. Water sits on top, one little crack or pinhole will allow the water to enter the substrate resulting in peeling. If these items are not maintained the wood will start to get cracks in it resulting in shorter periods between repaints. Galvanized metal will not peel if primed properly when it was originally painted. If this was not done the only way to fix it is to strip the substrate, prime with a galvanized metal primer, and finish coat with a 100% acrylic paint.