Sunday 16 December, 2018

9 top tips for painting this Christmas

The Christmas season is upon us, so it's time to get cleaning, scrubbing and painting every surface in your house.

Before you break out the paintbrush though, check out the list below and see if the surfaces of your home are experiencing any of these common issues. 

The following are tips for repainting a variety of surfaces:

 

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 Causes:

•             Use of 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 the latex paint dry too fast.

Solution:

It may be possible to correct cracking paint 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; then re-painting.

If the cracking goes down to the substrate, remove all of the paint by scraping, sanding and/or the use of a heat gun.  Then prime and re-paint with a high-quality exterior latex paint.

 

Peeling

Loss of paint due to poor adhesion.  Where there is a primer and top coat, or multiple coats of paint, peeling may occur on some or all of the coats.

Possible Causes:

•             Seepage of moisture through uncaulked joints, worn caulk or leaks in the roof or walls.

•             Excess moisture escaping through the exterior walls (most likely if the paint is oil-based).

•             Inadequate surface preparation.

•             Use of a lower quality paint.

•             Applying an oil-based paint over a wet surface.

•             Early blistering of paint.

Solution:

Try to identify and eliminate the source of moisture.  Prepare the surface by removing all loose paint with scraper or stiff wire brush.  Sand rough edges and apply the appropriate primer.  Re-paint with a top quality acrylic latex exterior paint for best adhesion and water resistance.

 

Fading

Premature and/or excessive lightening of the paint colour, which often occurs on surfaces that get direct sun exposure.  Fading/poor colour retention can also be the result of chalking of the coating.

Possible Causes:

•             Use of an interior paint for an outdoor application.

•             Use of lower quality paint, which leads to rapid degradation (chalking) of the paint film

•             Use of a paint colour that is particularly vulnerable to UV radiation (most notable, certain bright reds, blues & yellows).

•             Tinting a white paint that is not intended for tinting, or over-tinting 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.  When re-painting, be sure to use a quality exterior house paint in colours that are recommended for exterior use.

 

Alligatoring

Patterned cracking in the surface of the paint film, which resembles the scales of an alligator.

Possible Causes:

•             Application of an extremely hard, rigid coating such as 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 oil-based 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 careful to avoid igniting the paint substrate.  The surface should be primed with a high-quality latex or oil-based primer, then painted with a top quality exterior latex paint.

 

Poor Gloss Retention

Deterioration of the paint film, resulting in excessive or rapid loss of lustre of the top coat.

Possible Causes:

•             Use of an interior paint outdoors.

•             Use of a lower quality paint.

•             Use of a gloss alkyd or oil-based paint in areas of direct sunlight.

Solution:

Direct sunshine can degrade the binder and pigment of a paint, causing it to chalk and lose its gloss.  While all types of paint will lose some degree of lustre over time, lower quality paints will generally lose their gloss much earlier than better quality grades.  The binder in top quality acrylic latex paints is especially resistant to UV radiation, while oil and alkyd binders actually absorb the radiation causing the binders to break down.  Surface preparation for a coating showing poor gloss retention should be similar to that used for chalking surfaces.

 

Chalking

Formation of a fine powder on the surface of the paint 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 from heavy chalking.

Possible Causes:

•             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, scrubbing with a stiff bristle brush (or wire brush on masonry).  Then rinse thoroughly, 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 quality oil-based or acrylic latex primer (or a comparable sealer for masonry).

Then, re-paint with a quality exterior coating.  If little or no chalk remains and the old paint is sound, no priming is necessary.

 

Mildew

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

Possible Causes:

•             Forms most often on areas that tend to be damp and that receive little or no direct sunlight. (Walls with no sun exposure and the underside of eaves are particularly vulnerable.)

•             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 to distinguish mildew from dirt by applying a few drops of household bleach to the discolored area.  If the discoloration disappears, it is probably mildew.  Treat the mildew by applying a 3:1 solution of water and bleach.  When applying this solution, wear goggles and rubber gloves.  Leave the solution on for 20 minutes, applying more as it dries. The scrub and rinse the area. Apply an exterior latex primer, then a top-of-the-line exterior latex paint in a paint in a flat, satin, semi-gloss or gloss finish, depending on the desired appearance.

 

Poor Alkali Resistance

Colour loss and overall deterioration of paint film on fresh masonry.

Possible Causes:

•             Oil-based paint or vinyl acrylic latex paint applied to new masonry i.e. that had not cured for a full year.  Fresh masonry is likely to contain lime, which is very alkaline. Until the lime has a chance to react with carbon dioxide from the air, the alkalinity of the masonry remains so high that it can attack the integrity of the paint film.

Solution:

Allow masonry surfaces to cure for at least 30 days – ideally for a full year – before painting.

If this is not possible, the painter should apply a quality, alkali-resistant sealer or latex primer, followed by a top quality, 100-percent acrylic latex exterior paint.  The acrylic binder in these paint resists alkali attack.

 

Efflorescence/Mottling

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

Possible Causes:

•             Failure to adequately prepare the 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 siliconised acrylic caulk.  If moist air is originating inside the building, consider installing vents or exhaust fans, especially in the 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.  Allow the primer or sealer to dry completely, then apply a coat of top-quality exterior house paint, masonry paint or elastomeric wall coating.

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