Painting Exterior Surfaces
To avoid extra work when doing exterior painting, it is wise to have a good plan of attack. Important considerations should be the sequence and procedures you follow in applying your paint. Here are some guidelines:
• As a general rule, work from the top down so that you don’t drip onto areas that have already been repainted.
• Start by painting fascia boards, gutters and eaves; then tackle the walls; next, paint your downspouts; finish the job by painting windows, doors and trim.
• When painting lap siding, work horizontally by applying paint all the way across several boards (stopping in the middle of a board can cause an unsightly “lapping” effect, which may show up immediately, or after a year or two of weathering). Likewise, on vertical siding – grooved plywood or board-and-batten, for example – complete one vertical section at a time, then move on to the next section.
• Regardless of the surface you are painting, don’t stop painting until you reach a visual breakpoint.
Paint in the Right Weather Conditions
When it comes to painting, all days are not created equal. And don’t assume that just because a day is rain-free that it is a good day to paint. If the day is too hot or too windy, your paint may dry too quickly to enable it to form the most protective film. In fact, painting in the wrong conditions can even lead to premature flaking and peeling of the paint.
So, when should you paint? Here are some tips that will help you get the best results with exterior latex paints:
• Try to do your exterior painting on days when the temperature is between 60° and 85°F. (l5.56°C and 29.4°C) with low or moderate humidity and little or no wind.
• Even on moderate days, it is best to avoid painting in direct sunlight, since exterior surface temperatures can be 10 to 20 degrees F higher (5 to 11 degrees C) than the air temperature – too hot for good paint film formation. Do this by working your way around the house so that you are always painting in the shade, especially in the warmer afternoon hours. As a bonus, you’ll be more comfortable working this way.
• At the other extreme, avoid painting when the temperature falls below 50 degrees F (10°C), since cold temperatures can also prevent latex paint from forming a good protective film. Remember, too, that certain sides of the home get less sunshine, so the surface there may be even colder than the air temperature. The north side of the home is especially vulnerable this way.
• You can apply latex paints just 30 minutes after it rains, assuming that the surface is not visibly wet. (If you are applying oil-based paints, you should wait until the surface is completely dry.)
• Avoid painting in windy weather. Even light wind can cause latex paint to dry too quickly, resulting in inadequate film formation. Moreover, wind can stir up dust and other contaminants that can ruin your paint job.
Painting Special Exterior Surfaces
Although many of the steps involved in painting wood siding are also required when painting other surfaces, different procedures are sometimes necessary with certain types of exterior surfaces. These include masonry, aluminum siding and vinyl siding.
Masonry exteriors, including stucco, brick and concrete block, can all be successfully painted with top quality paints, but you must take certain precautions when painting these surfaces.
To begin with, recognize that good surface preparation – as with all paint jobs – is critically important when painting masonry. To that end, the masonry should be sound; free of dirt, powdery dust, and loose chalk; and rough enough so that the primer or paint can get a good grip on the surface. The best ways to clean and roughen the surface are to use a bristle brush, wire brush or – in extreme cases – a sandblaster, followed by a thorough rinsing.
New unpainted masonry or unpainted masonry that has aged less than a year presents some special challenges: for one, it may still contain moisture from the original mixing; for another, it may have a high degree of alkalinity. Aging and weathering will naturally rid the surfaces of these problems. However, if you are unwilling or unable to wait for this to happen, take these points into account:
Oil-based and vinyl water-based paints can fail prematurely if applied directly to a masonry surface aged less than one year; an alkaline-resistant sealer must first be used.
100% acrylic latex paints tend to resist the alkaline nature of fresh masonry, so they often can be applied directly to these surfaces. However, it is still best to apply an alkaline-resistant primer or sealer, even with a 100% acrylic latex paint, if the masonry is less than four weeks old.
Be it previously painted or unpainted, entails other considerations. If efflorescence (white, crusty salt deposits on the surface of the material) is present, for example, you must remove it during surface preparation by scraping, wire-brushing or sandblasting. Furthermore, if your masonry shows a tendency to produce efflorescence – or if it is very porous or chalky – you should apply a sealer or latex block filler before painting.
Finally, if you are applying water-based latex coatings to any type of masonry, it is advisable to first dampen the surface. Pre-dampening will allow the paint or coating to dry more slowly, which in turn, will enable it to form a more durable film.
To paint aluminum siding, begin by cleaning the surface in the standard fashion, either by power washing or hand-washing with warm, soapy water. Then rinse the surface thoroughly.
The unique challenge with aluminum siding is surface oxidation, which occurs when bare metal is exposed due to extreme chalking of the original factory applied coating on the surface of the panels. If your siding has unsightly white oxidation, carefully remove all of it by rubbing it away with steel wool. Rinse off the surface to eliminate any residue. And, if any bare aluminum is exposed, spot-prime those areas with a quality acrylic latex primer.
When it comes time to paint, use a top quality 100% acrylic latex California Paints exterior paint. This type of paint will provide good adhesion to aluminum siding and excellent resistance to fading. From an aesthetic standpoint, top quality latex paint forms a thick, uniform paint film that will faithfully duplicate the original surface profile of the siding, be it smooth or textured.
Vinyl siding is one of the best exterior surfaces to paint. ..and one of the easiest. All you need to do is to clean the siding thoroughly and remove any mildew with a bleach solution, then rinse the surface clean. Be sure that you don’t skimp on the quality of paint you use when painting vinyl siding. Because the siding panels may have a slick surface, you need a top quality paint with excellent adhesion characteristics. Your best choice is a top quality acrylic latex paint. Oil-based paints should not be used on vinyl siding. Finally, keep in mind the things that you shouldn’t do when painting vinyl siding:
• Don’t scrape, sand or wire-brush the siding during surface preparation. These actions can permanently mar the panels.
• Don’t paint the siding any darker than its original color. Dark paint colors can cause the siding to absorb the heat of the sun, and that can permanently warp and ruin the panels.
The core content for Painting Tips is provided by the courtesy of Dow Chemical as found on CaliforniaPaints.com.