Why do some five-year-old paint jobs peel and flake while others done sometime during the Reagan era look as if they were laid on last week? The answer is deceptively simple: Quality exterior paint — when it’s properly applied over a well-prepped surface — lasts longer than the cheap stuff. But trying to find the good stuff at the store can be an experience in sensory overload. Besides pondering the oil-vs.-water-based dilemma, homeowners have to choose from among several lines from each of the national brands as well as from locally produced products. And, while price usually indicates quality, with some exterior paints tagged at $40 per gallon, going by price alone can get expensive. Fortunately, there are some other indicators that will help you buy the right paint — if you know what they are. So whether your next exterior-painting project is imminent or a few years off, read on to find out what, according to independent researchers and industry experts, makes a quality product. You’ll also pick up some helpful tips on both the all-important prepping process and the esthetic science of choosing colors.
For years, there’s been a lively debate about the supremacy of oil-based or water-based paint. Oil-based products, which include alkyd paints, clean up with mineral spirits. Water-based products, which are referred to as latex paints though they are now based on vinyl and acrylics, clean up with water. Although the question still gets asked, water-based paints win hands down for home exteriors. Research done at the U.S. Department of Agriculture Forest Products Laboratory (FPL) in Madison, Wisconsin, shows that water-based paints expand and contract with the siding. They also allow water vapor generated inside the house to pass through the paint film. Oil-based paints, on the other hand, dry to an inflexible coating that blocks moisture. The results can be telltale cracks as siding gives and paint blisters as trapped moisture tries to find a way out. Water-based paints are also gentler on the environment because they are lower in volatile organic compounds. Does that mean oil-based paint should not be used at all? Certainly not. “When asked to recommend a paint,” says Al Beitelman, director of the Paint Technology Center for the U.S. Army Corps of Engineers, “I always ask about the previous paint job. If it worked fine, I suggest using what was there before.”
The premium line from any manufacturer will almost certainly cover better and last longer than its less-expensive versions. Because the expense of painting is mostly in the labor, it makes sense to buy premium paint. But suppose you plan to move or want to change the color scheme of your home in the next few years. Here’s where you can save with a midlevel paint that’s backed for 10 years or so versus 15 or more for many top-of-the-line paints. “We find customers really don’t believe warranty claims,” says Lane Blackburn, vice president of architectural marketing for Sherwin-Williams. “But they do use the warranty as a guide to quality.” For example, Ace Hardware, like most retailers, offers two exterior-paint lines: Royal Shield ($20 to $25 per gallon, 15-year warranty) and Quality Shield ($16, 10-year warranty).
There are other ways to pick quality exterior paint out of a lineup:
Proper pigments. Quality pigments allow a good paint to cover fully with just one coat. Paints with lower-cost pigments often must be applied in several coats. That means more work, which makes buying low-quality paint a poor financial decision. The best pigment is titanium dioxide. Look for it when ingredients are listed on the can.
High percentage of solids. The solids are what’s left on the wall after the paint has dried. Anything over 45 percent is considered good; the higher the level of solids, the better, because you’ll wind up with a denser, more durable coating. For example, a gallon of Dulux Exterior Flat contains 52 percent solids by weight. However, be aware that some companies add cheap fillers to beef up the percentage of solids – that makes it wise to stay away from inexpensive paints with a high level of solids. Although you typically won’t find information about solids on the label, check with your paint retailer, ask to see product data sheets or fire up your modem and check the company’s Website.
All-acrylic binder. The binder is what holds the pigments, mildewcides and other solids that form the actual paint film. Look for latex paint with an all-acrylic binder, which is inherently more weather resistant than vinyl or vinyl-acrylic. Many paint companies use a modified acrylic for their interior lines and all-acrylic for premium exterior paints made to endure the elements. For example, Glidden’s Spred Satin is an interior with a modified acrylic, while its Spred Dura Satin is an exterior paint with an all acrylic binder. If you don’t see “100% Acrylic” or “All Acrylic” in bold on the front of the can, check ingredients for “acrylic polymer.” Also be sure you pick the right paint for the surface you’re covering. Most water-based exterior paints can be used on wood and hardboard siding and trim. They’re also fine for vinyl and aluminum siding, and most masonry. On stucco prone to cracking, use an elastomeric paint. It’s more flexible than standard coatings and leaves a durable film that’s twice as thick (about 5 mil). An example is the stucco paint from Valspar, which bridges hairline cracks to keep out water. You can also buy paint tailored to conditions in specific regions of the country. Dutch Boy’s ClimateGuard line was the first of these paints from a major manufacturer. For example, its Southeast formulation has extra mildewcides for a humid climate, while Northwest paint is higher in solids to resist months of rainfall.
Choosing and matching colors can be nerve-wracking, which explains why there are so many white houses. Fortunately, paint companies are taking the pain out of this process. Many offer color cards that suggest color combinations for siding and trim. Several have also come up with other approaches. For example, Sears tracked colors customers preferred and those found in nature for its Weatherbeater line. Research by the company yielded palettes that correspond to different regions of the country – one set of colors for the coasts, one for the Sun Belt and a third for the center of the country. Color experts from The Home Depot came up with 30 popular combinations from its Behr line that range from soft pinks and peaches to bold rusts and blues. And if you have a classic home, or even a modern classic, the Sherwin-Williams Preservation palette offers a range of historical hues. Most paint dealers will also help you win the match game. Some offer color-matching software. For instance, Benjamin Moore dealers will also scan a photo of your house and let you experiment with color on a computer screen. Or you can choose a house from the program that looks like yours. Whichever method you use, remember that your roof and landscaping, along with the other houses on the street, won’t change. So consider these permanent colors when making your selection. And favor lighter hues, suggests Mark Knaebe, a chemist at the FPL. Dark colors absorb heat and are more likely to suffer from moisture problems.
Even the best exterior paint can fail if it’s applied incorrectly. Always use a primer when painting any untreated surface to seal it off and to provide a base for topcoats to stick to. Alkyd primers are best for bare wood because they cover bleed-through from wood knots better; be sure the label states that the primer is designed to stop bleed-through. Water-based primers are a good choice if knots aren’t an issue. Water-based paints are compatible with both types of primer. When repainting, prime only when necessary. If the paint hasn’t cracked or flaked, you may not need to prime at all. Advantage 900 from Porter Paints is designed to go over any existing paint without priming or sanding. If you must scrape down to bare wood, spot-prime. Not sure whether priming is needed? Try this test: Paint a small portion of the wall and let it dry. Then put an adhesive bandage on the newly painted surface and snap it off. If paint sticks to it, the old paint won’t support a new coat and requires a coat of primer. If the bandage is clean, power wash the siding and paint. For painting new construction, the FPL recommends dipping each piece of siding in a paintable water repellent, priming, then applying two coats of water-based paint. The lab also suggests installing siding on furring strips, creating a ventilated space behind it to reduce vapor. Seal the bottom with screening to keep insects out. If you hire a painting contractor, be sure he or she follows the paint manufacturer’s directions. For example, the temperature should be between 50° and 90°F to apply water-based paint. Also, the topcoat should go on within two weeks of the primer. If you wait too long, the mechanical bond between the two won’t be as strong because the surface texture of the primer breaks down. And if two topcoats are used (recommended for new construction), the second should go on within two weeks of the first. There are lots of exterior paints out there. Knowing how to pick the best from a lineup of look-alike cans will help your paint job last well into the next century.