We apply two coats to pine boards, then mount the boards on angled racks on the roof of our headquarters in Yonkers, N.Y. to see how well the paint withstands the elements. We also check how well the paint resists cracking, fading, and dirt buildup. Because the boards are angled, and not placed vertical as they would be on your house, they’re more exposed to the elements.

“Each year of testing is about three years on vertical surfaces,” says Rico de Paz, the engineer who oversees our tests of paints and stains.

“After three years, our results give you an idea of how the paint will look after nine years.” We also test for mildew resistance by placing painted panels on vertical racks in a shady area of our grounds.

Putting your stamp on it. You love turquoise, doesn’t everybody? You won’t be repainting your house for another eight years or so, and if you’re putting it on the market before that know that some house hunters won’t even look inside if they don’t like the exterior paint color. They’re thinking of the thousands they’ll have to spend to have it repainted.

Tips: Be a good neighbor and think how the color fits in. “You don’t want to be a total oddball on the street, but you don’t want a color that’s too close to homes next door,” says Harrington. “And the better the street looks, the more value it has.” You can add interest to your home’s exterior by painting the front door a color you love—it’s easy and inexpensive to change.

Overlooking natural light. In the South, pink houses can charm, but that’s harder to pull off up north, and the color of San Francisco’s painted ladies won’t work in Boston. Natural light plays an important role here and makes colors look lighter.

Tips: The exterior paint color you first pick might look washed out once it’s on your house. Pick a color that’s one or two shades darker than what you think you want, or go a shade grayer. Paint a swatch on the front of your house where it’s in full sun, not on the porch or overhang where there’s shadows. Look at the color at different times of day.

Ignoring details. The color of the roof, window trim, sashes, and even the mortar matter.

Tips: The mortar around the bricks is typically off-white, beige, or gray. So match trim to the mortar color for a look that’s warm and more natural, rather than painting it a bright white. If the roof has red or brown tones it can clash with a gray or green exterior, while black and gray act as neutral roof colors. When choosing a color for the window trim, consider the color of the window sash and whether it can be painted. Vinyl windows often have a white or beige sash and can’t be painted.

Buying the wrong paint is a mistake you can easily avoid by checking the results of our tough paint tests. Read on for the top performers in our paint ratings.