Q: I have heard that painting outside in the fall and spring is not a good idea because of the dampness in the air. I plan on using latex paint. How late or early in the season can I paint and still have long-lasting results? I live in the Midwest.
A: If you need to paint outside with latex paint when temperatures are moving up and down like a yo-yo, I suggest you use one of the latex like Duration, Resilience, or SuperPaint. These products can be applied and will cure at lower temperatures, as low as 35° F. Traditional latex-based paints need temperatures above 60° F to cure properly. Warmer temperatures are needed to allow the latex particles to coalesce, or melt together. That is why the spring and fall can be tricky times to paint outside. A common mistake is to paint when the daytime high temperature gets above 60° F and the nighttime temperatures get much cooler because dew forms on almost everything as soon as the sun goes down. Even though the temperature was OK at the time of application, the paint can stop coalescing. This permits moisture to get into the uncured paint film allowing certain ingredients to come to the surface when the moisture evaporates, causing surface staining and possible adhesion problems.
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 sweat-in or induction time?
A: These terms refer to the waiting period required between the time you mix and the time you can start applying a two-part product, such as an epoxy. This allows the necessary chemical reactions between the two parts to begin so the coating will cure and perform properly.
Q: When daytime and nighttime temperatures differ significantly, should I be concerned about when to stop painting?
A: Yes. You want to follow the label directions for the product you are using. Most products require at least 4 hours of dry time before moisture can settle on the surface. The cooler the temperature the sooner you should stop painting.
Q: What is the optimal temperature to paint outside?
A: Until a few years ago you needed to paint above 50° F. Sherwin-Williams now has products like Duration, Resilience, SuperPaint and A-100 Exterior that will allow you to paint down to 35° F.
Q: What is the best method of applying an elastomeric?
A: Rolling is usually the best method. Consult the Product Datasheet for specifications and recommendations on this. If applying by airless, you should use .021 to .031 tips because this is a fairly heavy-bodied material. When working with a low-texture material, the spray unit must be specifically designed for aggregate coatings. Generally, you can spray on 20 to 30 wet mils by cross coating (a horizontal coating pattern followed by a vertical coating pattern). When rolling, almost invariably a minimum of two coats will be needed to achieve the acquired film thickness. When applying over flat surfaces like poured-in-place concrete, simple spraying works well. When applying over rough surfaces like stucco, spraying would have to be followed by backrolling. Backrolling involves an additional pass with a wet, but not loaded roller, that will force the material into contact with all dips and holes in the surface.
Q: What about the problem of roller-tracking when applying elastomeric coatings? How can this be avoided?
A: Because this material goes on with a heavy film thickness, there is a tendency to roller-track. To avoid the problem, the painter should "dress down" when rolling. In other words, before redipping, always finish rolling with a downward roll. This will give the same repeat pattern throughout the job.
Q: Which produces the better, longer lasting paint job on aluminum siding, spraying or brushing?
A: The key thing to consider when repainting aluminum siding is not the method of application, but the surface prep. Aluminum siding is normally painted only after it has faded and chalked. If the chalkiness is not removed, the paint will not adhere properly. Spraying will be much quicker than brushing, and as long as the proper tip size and pressure are used, it will produce excellent results. Duration, Resilience, or SuperPaint Exterior Acrylic, applied to a properly prepared surface will produce a quality long lasting finish.
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: When using an oil-based product, how much time is needed for the product to set up sufficiently to withstand rain or precipitation?
A: A minimum of eight hours is recommended when the temperature is above 70° F. The cooler the temperature the longer the wait.
Q: What happens to paint that is applied during summer, when it is really hot and humid?
A: Extremely high temperatures (over 100° F) could cause a paint film to dry before it has had a chance to properly adhere to the surface. This can cause it to peel in the future.
Q: What is the best time of year to stain exterior surfaces?
A: Whenever it's dry and warm. Although 70° F is the ideal temperature for exterior staining, the "safe range" spans from 50° F to 90° F. Avoid staining when humidity is high or the day after a rainstorm, and never stain in direct sunlight. As always, check the label for product-specific directions.
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: How late into fall can I paint house exteriors with latex paint and give customers long-lasting results?
A: Fall can be a tricky time to paint outside. A common mistake is to paint when daytime temperatures rise above 50° F and nighttime temperatures drop below 35° F. Even though the temperature may be acceptable at the time of application, the paint can stop coalescing, or melting together, when the temperature drops. Additionally, dew will form on almost everything as soon as the sun sets, and seep into the uncured paint. When the moisture evaporates, certain ingredients rise to the surface causing surface staining and possible adhesion problems. My best advice is to use a paint made for painting at 35° F and above, like Duration, Resilience, Super Paint or A-100 Exterior products.
Q: What is the advisability of mixing topcoat paint with primer in order to tint the primer?
A: This technique is not recommended by paint manufacturers, and if done, can result in coating failure. We suggest the Sherwin-Williams Color-Prime System for shading primers.
Q: Every fall, I switch to oil-based paint for my exterior jobs since I can use it at lower temperatures than latex. Sometimes, though, I find the oil paint hard to work with early in the morning. Why?
A: There are a couple possible causes. It could simply be too cold to be painting outside in the morning. The temperature may not be high enough to allow the paint to flow and cure properly. Or, if you store the oil paint outside or in your truck, it is exposed to colder temperatures during the night that cause it to thicken, just like the motor oil in your truck. To avoid problems, be sure to follow the manufacturer's label direction for recommended application temperatures; and remember that they refer to air, surface, and material temperatures. It's also a good idea to store your oil-based paint inside or allow it plenty of time to warm up before you begin work in the morning.
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.
Q: In cold weather, why will dark colors turn white or frosted looking?
A: When latex paint is applied in temperatures below the manufacturer's recommendation or when the paint is exposed to low temperatures and/or high humidity too soon in its curing process, it doesn't form a proper film. To get rid of the "frosting," rinse the surface thoroughly with warm water. A garden hose works best because you need a lot of water, not a lot of pressure.
Q: Why would a popcorn texture peel and fall off in sheets after a latex paint is applied?
A: When latex is applied over a "popcorn" ceiling, the water in the paint can break down the adhesive bond between the texture and the substrate, allowing the weight of the texture to pull the material off the ceiling. Applying an alkyd primer before repainting with latex will usually alleviate the problem.
Q: Mixing instructions for two-part epoxies and urethanes mention a potlife of so many hours. Does this mean the paint turns solid in that amount of time?
A: In some high-solids materials, the liquid will become solid at the end of the potlife. In most cases, though, the potlife refers to the amount of time you have to apply the coating before it gets to a critical point in the chemical reaction between the two parts. After the potlife period expires, the material will become difficult to apply and the adhesion, cure, and performance of the coating will be adversely affected. When working with these types of products, it's best to mix only what you can use within the potlife listed by the manufacturer.
Q: There seems to be a lot of discussion about the best method to paint the exterior of a house. Some say use a brush, some claim it is best to spray on the paint and then back-brush it, and others say just using an airless sprayer is best. What do you think?
A: Painting with an airless will usually get more paint on the surface than with a brush. If applied properly - keeping the gun 12" away from the surface at a 90° angle and applying the recommended mil thickness of paint - airless spraying is the most efficient way to paint most large exterior surfaces. Brushing, while you are able to work the paint into the surface, takes considerably longer. For windows and intricate trim work, you almost have to brush the paint on the surface.
Q: What is the best way to paint the exterior of a house? Spraying would seem fastest. I have a compressor, should I buy a spray gun or airless equipment? What about back brushing or rolling, should this be done also?
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.
Q: What is the best tool for painting standard wood house exteriors? Should I use a brush or roller? Or perhaps a combination?
A: It really depends on how wide the surface is that you're painting. If you're painting big surfaces like plywood siding, 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.