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Exterior Painting

Alligatoring

Patterned cracking in the surface of the paint film resembling the regular scales of an alligator.

Possible Cause:

  • Application of an extremely hard, rigid coating, like an alkyd enamel, over a more flexible coating, like a latex primer

  • Application of a top coat before the undercoat is dry

  • Natural aging of alkyd paints as temperatures fluctuate. The constant expansion and contraction results in a loss of paint film elasticity

Solution:

Old paint should be completely removed by scraping and sanding the surface; a heat gun can be used to speed work on large surfaces, but be sure to take care to avoid igniting paint or substrate. The surface should be primed with a high quality latex or alkyd PARA PRIMETECH primer, then painted with a top quality PARA ULTRA Exterior Acrylic Latex Paint.

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Blistering

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

Possible Cause:

  • 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 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 an exhaust fan. Remove blisters. If blisters do not go all the way down to the substrate, remove them by scraping, then sanding; prime any bare wood and repaint with a PARA ULTRA top quality Exterior Paint.

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Chalking

Formation of fine powder on the surface of the paint film during weather, which can cause color 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 a low-grade, highly pigmented paint

  • Use of an interior paint for an outdoor application

Solution:

First, remove as much of the chalk residue as possible using a stiff bristle brush (or wire brush on masonry) and then rinse thoroughly with a garden hose; or use power washing equipment. Check for any remaining chalk by running a hand over the surface after it dries. If noticeable chalk is still present, apply a top quality PARA PRIMETECH alkyd or acrylic latex primer (or sealer for masonry), then repaint with a top quality PARA ULTRA Exterior Paint. If little or no chalk remains and the old paint is sound, no priming is necessary.

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Chalk Run Down

The washing down of chalk from an excessively eroding paint onto another area below (a brick foundation, for example), ruining its appearance (see Chalking).

Possible Cause:

  • Use of a lower quality, highly pigmented paint

  • Use of interior paint for an outdoor application

  • Erosion of factory-finished metal siding

Solution:

Remove as much of the chalk residue as possible (see Chalking). Scrub any stained areas with a stiff brush, using a detergent solution, rinse thoroughly. In cases of severe staining, an acid wash may be necessary. Either way, if the affected area dries to a different color, consider painting it with a quality acrylic latex paint. Eroding aluminum siding should be thoroughly cleaned (power washing recommended) before painting with a top quality PARA ULTRA pure Acrylic Latex Paint.

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Cracking/Flaking

The splitting of a dry paint film through at least one coat, which will lead to complete failure of the paint. Early on, the problem appears as hairline cracks; later, flaking of paint chips occurs.

Possible Cause:

  • Use of a lower quality paint that has inadequate adhesion and flexibility

  • Over thinning the paint or spreading it too thin.

  • Poor surface preparation, especially when the paint is applied to bare wood without priming

  • Painting under cool or windy conditions that make latex paint dry too fast.

Solution:

It may be possible to correct cracking that does not go down to the substrate by removing the loose or flaking paint with a scraper or wire brush, sanding to feather the edges, priming any bare spots and repainting. If the cracking goes down to the substrate, remove all of the paint by scraping, sanding and/or use of a heat gun; then prime and repaint with top quality PARA ULTRA pure Acrylic Latex Paint.

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Dirt Pickup

Accumulation of dirt, dust particles and/or other debris on the paint film; may resemble Mildew

Possible Cause:

  • Use of a low quality paint, especially lower grades of satin or semi gloss finishes

  • Soil splashing onto siding

  • Air pollution, car exhaust and flying dust collecting on house body and horizontal trim

Solution:

Wash off all surface dirt before priming and painting. If unsure whether the problem is dirt or mildew, conduct a simple spot-test (see Mildew). Clean off dirt with a scrub brush and detergent solution, followed by a thorough rinsing with a garden hose. Heavier dirt accumulation may require the use of a power washer. While dirt pickup can't be eliminated entirely, top quality exterior latex paints typically offer superior dirt pickup resistance and washability. Also, higher gloss paints are more resistant to dirt pickup than flat paints, which are more porous and can more easily entrap dirt.

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Efflorescence/Mottling

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

Possible Cause:

  • Failure to adequately prepare surface by removing all previous efflorescence

  • Excess moisture escaping through the exterior masonry walls from the inside

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 or power washer; then thoroughly rinse the surface. Apply a top quality PARA PRIMETECH Acrylic Latex or Alkyd masonry sealer and allow it to dry completely; then apply a coat of top quality PARA ULTRA Acrylic Latex Exterior House Paint.

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Fading/Poor Colour Retention

Premature and/or excessive lightening of the paint colour, which often occurs on surfaces with sunny southern exposure. Fading/poor colour retention can also be a result of chalking of the coating.

Possible Cause:

  • Use of an interior grade of paint for an outdoor application.

  • Use of a lower quality paint, leading to rapid degradation (chalking) of the paint film

  • Use of a paint colour that is particularly vulnerable to UV radiation (most notably, certain bright reds, blues and yellows). Tinting a white paint not intended for tinting, or overtinting a light or medium paint base

Solution:

When fading/poor colour retention is a result of chalking, it is necessary to remove as much of the chalk as possible (see chalking). In repainting, be sure to use top quality PARA ULTRA Exterior Paint. All PARA exterior colours are fade resistant.

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Frosting

A white, salt-like substance on the paint surface. Frosting can occur on any paint colour, but it is less noticeable on white paint or light tints. On masonry, it can be mistaken for efflorescence. Forms mostly in protected areas (such as under eaves and on open porch ceilings) that do not receive the cleansing action of rain, dew and other moisture.

Possible Cause:

  • Use of dark coloured paints that have been formulated with calcium carbonate extender

  • Application of a dark-coloured paint over a paint or primer containing calcium carbonate extender

Solution:

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 top coat 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, then apply a PARA PRIMETECH Alkyd Primer before adding a coat of high quality PARA ULTRA Exterior Paint.

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Lapping

Appearance of a denser colour or higher gloss where wet and dry layers overlap during paint application

Possible Cause:

  • Failure to maintain a "wet edge" when applying 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 from "wet to dry," rather than vice versa) will help produce a smooth, uniform appearance. It is also wise to minimize the area being painted and plan for interruptions at a natural break, such as a window, door or corner (especially important when applying stain to bare wood). Alkyd paints generally have superior wet edge properties.

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Mildew

Black, grey or brown areas on the surface of paint or caulk. Forms most often on areas that tend to be damp, and receive little or no direct sunlight (walls with a northerly exposure and the underside of eaves are particularly vulnerable).

Possible Cause:

  • Use of a lower quality paint, which may have an insufficient amount of mildewcide

  • Failure to prime bare wood before painting

  • 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 discoloured area; if it disappears, it is probably 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, prime any bare wood, then apply one or two coats of a PARA ULTRA top quality Exterior Paint with mildewcide.

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Nailhead Rusting

Reddish-brown stains on the paint surface.

Possible Cause:

  • Non-galvanized iron nails have begun to rust, causing bleed-through to the top coat

  • Non-galvanized iron nails have not been countersunk and filled over

  • Galvanized nailheads have begun to rust after sanding or excessive weathering

Solution:

When painting new exterior construction where non-galvanized nails have been used, it is advisable to first countersink the nailhead, then caulk them with a top quality, water-based all-acrylic or siliconized acrylic caulk. Each nailhead area should be spot primed, then painted with a quality acrylic latex coating. When repainting exteriors where nailhead rusting has occurred, wash off rust stains, sand the nailheads, then follow the same surface preparation procedures for new construction.

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Paint Incompatibility

Loss of adhesion where many old coats of alkyd or oil-based paint receive a latex top coat.

Possible Cause:

  • Use of water-based latex paint over more than three or four coats of old alkyd or oil-based paint may cause the old paint to "lift off" the substrate

Solution:

Repaint using another coat of alkyd paint. Or completely remove the existing paint and prepare the surface - cleaning, sanding and spot-priming with a high quality PARA PRIMETECH primer where necessary, before repainting with a top quality PARA ULTRA Acrylic Latex Exterior Paint.

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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 un-caulked joints, worn caulk or leaks in roof or walls

  • Excess moisture escaping through the exterior walls (more likely if paint is alkyd)

  • Inadequate surface preparation

  • Use of lower quality paint

  • Applying an alkyd paint over a wet surface

  • Earlier blistering of paint (see Blistering)

Solution:

Try to identify and eliminate cause of moisture (See Efflorescence/Mottling). Prepare surface by removing all loose paint with scraper or wire brush, sand rough surfaces, and prime bare wood with a suitable PARA PRIMETECH primer. Repaint with a PARA ULTRA top quality Acrylic Latex Exterior Paint for best adhesion and water resistance.

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Surfactant Leaching

Concentration of water-soluble ingredients of 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 coloured paints.

Possible Cause:

  • Painting in cool, humid conditions or just before they occur. The longer drying time allows the paints water-soluble ingredients, which would normally evaporate, to be leached out by rain or dew and 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.

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Tannin Staining

Brownish or tan discoloration on the surface due to migration of tannin from the substrate through the paint. Typically occurs on "staining woods" (e.g. redwood, cedar and mahogany) and knots in certain other wood species.

Possible Cause:

  • Failure to adequately prime and seal the surface before applying the paint

  • Use of a primer that is not sufficiently stain-resistant

  • Excess moisture escaping through the exterior walls, which can carry the stain to the paint surface.

Solution:

Correct any possible sources of excess moisture (see Efflorescence/Mottling). After thoroughly cleaning the surface, apply a PARA PRIMETECH high quality stain-resistant Alkyd or Acrylic Latex Primer. Alkyd stain-resistant primers are the best type to use on severely stained boards. In extreme cases, a second coat of primer can be applied after the first has dried thoroughly. Finish with PARA ULTRA top quality Acrylic Latex Paint.

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Vinyl Siding Warp

Warping or buckling of vinyl siding panels that have been repainted

Possible Cause:

  • Most likely cause is that vinyl siding was repainted with a darker colour paint than the original colour. Dark paint tends to absorb the heat of the sun, transferring it to the substrate. When vinyl siding expands dramatically, it is not able to contract to its original dimensions.

Solution:

Paint vinyl siding in a shade no darker than the original. White, off-whites, pastels and other very light colours are good choices. PARA ULTRA top quality Acrylic Latex Paint is the best type of paint to use on vinyl siding, because the superior flexibility of the paint film enables it to withstand the stress of expansion and contraction cycles caused by outdoor temperature changes. Siding that has warped or buckled should be assessed by a siding or home repair contractor to determine the best remedy. The siding may have to be replaced.

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