Exterior: Product Application FAQs

Q: When painting outside, how long does the temperature need to stay in the suggested range? Some people say it's okay to paint all day, even if the temperature is above the minimum recommendation for only an hour or so.

  • A: Ideally, the temperature should be in the suggested range and above the dew point for at least 48 hours after application. Colder temperatures and moisture on the surface will not allow a paint film to form properly. This will shorten the life expectancy of the paint and could cause surfactant leaching, mildew growth, frosting, and adhesion problems. When the forecasters predict changing temperatures that may drop below the normal recommendation of 50° F for latex paint, consider using a house paint that can be applied and will cure at temperatures as low as 35° F. This will give you the opportunity to extend your painting season by as much as two months in most areas of the country.

Q: Is it better to brush or airless spray the exterior finish on smooth hardboard siding? What would be the longest lasting paint?

  • A: Spraying is faster. Brushing is neater. Many painters use a combination of the two methods by spraying to quickly get paint on the surface, followed by back brushing to spread the paint out evenly, resulting in a good looking finish. It may depend on how wide the surface is that you're painting as well. If you're painting big surfaces, cut in with a brush and roll the rest of the panel. For most siding areas, if you can't spray and backbrush, stick with a brush. Most siding areas are not wide enough to use a roller, so a good 4" brush that holds a lot of paint will work much better.

Q: What is the optimal temperature to paint outside?

  • A: Until a few years ago you needed to paint above 50° F.

Q: How can I avoid overlap marks when I'm painting?

  • A: Try not to paint too large of an area at one time. Overlapping occurs when a freshly painted section begins to dry before you start painting the adjoining area.

Q: What is the best method of touch-up?

  • A: To achieve acceptable touch-up results, it's important to apply touch-up by the same method as the original application, if possible, to avoid having any difference in sheen or texture. Be sure to use paint from the original batch, reduced 25 to 50 percent, and only apply a thin coat. It's also best to apply the touch-up paint under similar temperature and humidity conditions as the original.

Q: How long after it rains should I wait to paint?

  • A: That really depends on how wet the surface gets. A masonry or wood surface will absorb more moisture from a soaking rain than will aluminum or vinyl siding. I would wait a MINIMUM of one day after a heavy rain, but remember the surface must be dry before painting. Too much moisture in the substrate will prevent absorption and will most likely lead to peeling.

Q: Is it always bad to paint in direct sunlight?

  • A: It's best to avoid painting in direct sunlight, especially during the hot summer months. The heat from the sun's rays cause the paint to dry to quickly, which can cause a number of problems - brush marks, lap marks, inadequate adhesion. Move around the house to avoid the sun as much as possible.