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Sunbeams can affect a home's exterior paint like slow-acting kryptonite. Radiant sunlight will severely limit the lifetime of many water- and oil-based paints. In fact, many exterior paints will begin to blister or crack, look noticeably faded and display uneven gloss within seven years of application. Fortunately, you can select from a new generation of high performance paints that will keep your home looking attractive for decades.
The Best Paints for Wood Siding and Trim
A 100 per cent acrylic latex paint bonds firmly to wood siding and forms a flexible, breathable barrier that is waterproof and that resists the destructive heat and UV rays of the sun. Because they are vapour permeable, these paints won't blister when the sun heats up water vapour that might become trapped behind lower-grade coatings. A 100 per cent acrylic film is flexible enough to expand and contract through recurring heat cycles rather than cracking or flaking. Daily exposure to UV won't cause the paint film to begin dissolving, which can appear as surface chalking. And 100 per cent acrylic paints usually contain UV-resistant pigments to help keep the paint's colour from fading prematurely. One hundred per cent acrylic paints may cost twice as much as bargain-priced latex paints, but they will typically last 50 to 100 per cent longer.
Choosing Colors for Wood Siding and Trim
Most of the pigments used in latex or oil-based paints will fade over time when exposed to UV rays, so choose colours wisely. Deep colours will lose saturation after years of exposure to sunlight. Bright yellows often turn weak and muddy looking, bright reds may take on a maroon cast and plum may shift to dark lavender. The transition is less pronounced in neutral colours, which is why so many homes are painted in off-white shades. A 100 per cent acrylic paint will offer better fade resistance than a conventional latex or oil paint.
The Best Paint for Exterior Masonry Walls
Mineral silicate paints won't work with wood or other organic surfaces, but they are particularly well suited for sun-exposed concrete walls, cement-based stucco, fibre cement siding or masonry block walls. A mineral silicate paint bonds into the wall's pores and is unaffected by heat or UV rays. Depending on the colour selected, a mineral silicate paint will reflect the sun's destructive heat away from the surface and help the wall stay cooler. The colour palette for mineral silicate paints is much smaller, but mineral-based pigments are not vulnerable to UV rays, which means that whatever colour you choose should last for decades.
Best Weather Conditions for Application
The best time to apply a 100 per cent acrylic latex paint or a mineral silicate paint is on a dry, sunny day with temperatures between 10 and 31.1 degrees Celsius. Some manufacturers' instructions allow painting on days as cold as 35 degrees or as hot as 100 degrees. When the air temperature is in the 90s, however, the sun may heat exterior walls to a much higher temperature. Likewise, if the morning air temperature is in the 30s, the walls themselves may be much cooler if they have not have absorbed enough heat from the sun to warm up from an overnight frost. Applying paint in either weather extreme may lead to premature failure of the paint finish.
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