Exterior Spray Painting
Most professionals and homeowners select spray painting to save time and their backs. Paint spraying can apply a lot of primer or paint very fast saving days of manual labor, but this method has some limitations.
The main limitations are overspray and difficulty to control. Both of these can be overcome with planning and practice. Other limits deal with ruff surfaces. Paint spraying is great for smooth surfaces, but can’t properly fill the pores of stucco and concrete block.
Carefully examine the limits of spray painting and plan accordingly. Planning starts with the preparation of the home for painting. The same attention to details like removing peeling paint and applying caulking are the same as with any application method. The similarities stop when the masking begins.
Preparation Before Spraying Paint
Overspray is a big problem for airless sprayers and you need to cover all items completely. Assume anything near or in the immediate area when spray painting will get some overspray.
Cover all windows and doors completely with plastic and tape. Plus, any other items you don’t want painted will need to be removed or masked with paper or plastic. Don’t assume you can shield everything and get away with it.
Extensive areas must be covered with drop cloths. This includes sidewalks, decks and fences. Spraying slow drying materials on windy days, such as oil base primer or paints and stains, is a big risk. The overspray can drift for substantial distances. Placing neighboring houses, cars and plants at risk.
Paint Spraying Safety
Airless paint sprayers are inherently dangerous, producing pressures as high as 3000 psi. Never point the spray gun at another person or yourself. The stream of paint can be injected under the skin and will require immediate medical attention.
Other hazards while spray painting are to your lungs, eyes, skin and hair. Protect your lungs with a high quality particle mask or respirator with an approved rating for the type of material being sprayed. Eyes and skin are covered with safety glasses and a lightweight spray suit. Protect your hair with a “spray sock”. This is a light cotton or nylon ski mask. Any remaining facial skin can be covered with petroleum jelly. This will make cleanup easier.
All of this clothing will be difficult to work in on a hot day, but is necessary if you will be spraying oil base primer, paint or stain.
Airless Sprayers and Tip Sizes
Choosing an airless sprayer depends on the material being sprayed and the needed versatility. Sprayers are pumps driven by electric motors or a gasoline engine. Types with gasoline engines are more powerful and capable of pumping a variety if paints. This extra power is necessary for very thick coatings, such as Elastomeric paint. Electrically powered airless sprayers are more versatile. (Example- can be used indoors.) This makes them the best all around choice for regular primers and paints.
Tip size is also dependent on material being sprayed. Many homeowners and professionals choose a spray tip that is too large thinking this will speed up the spray painting. Yes a large tip will speed up the paint spraying, but will also produce unsightly runs or very thick areas.
A general rule for first time users is to use a smaller tip size than recommended by the manufacture for better control. A good example is the 517 tip.
This is a good spray tip for most exterior acrylic paints and is used by most professional painters. The 517 can apply a lot of paint quickly. Requiring you to move very fast and still maintain control when spraying. An alternative is to use a 515 instead. This offers better control without drastically slowing you down. To use the smaller tip you might need to thin or condition your paint.
This example applies to the thick exterior acrylic paints that are in use today. For oil base finishes a smaller tip is necessary. Do some experimenting with different tip sizes in order to find what is right for you and the material you are spraying.
Correct Spray Painting Procedures
The best way to paint a house is from the top down, completing sections before continuing. This applies to siding, soffits and stucco.
An example of spraying paint a section at a time (corner to corner); Start at one end of a side and spray 6-8 feet of soffit then several (4-5 or more) pieces of siding. Now move across and repeat until the soffits and a few boards of siding are painted. Simply, lower your ladder and spray more siding, moving across. Repeat this procedure until you’re on the ground and the side is painted.
Paint spraying requires four basic procedures, with some exceptions depending on the surface being sprayed. After reading them you will realize most are common sense ideas. With some experience you will come up with some of your own.
The direction when spray painting can have a dramatic effect on the final appearance. Typically a horizontal direction across the surface works best. This will be a back and forth pattern with overlapping strokes.
- Keep the gun and tip perpendicular to the surface while spray painting. If you hold the gun at an angle more paint will be dispensed to one part of the spray pattern. The paint needs to be evenly applied across the entire surface.Avoid swinging the gun, left or right, at the end of each spray painting stroke. This will help avoid some of the overspray. Keeping the gun and tip straight at the surface will apply the proper amount of paint, avoiding the appearance of unpainted shadows caused by surface imperfections.
- Keep the gun and tip the correct distance from the surface. Manufactures rate their tips at 12 inches from the surface. This rating applies both the pattern size and shape. Although 12 inches is the optimum distance, 10-14 inches will suffice.If the gun is held to close to the surface, the material will build up to quickly causing runs or sags. To far away can produce a ruff finish, similar to sand paper, as each droplet of paint dries independently of each other.
- Keep the gun moving before, during and after the trigger is pulled. Airless sprayers will apply a lot of paint very quickly. If the trigger is pulled before the gun is in motion excess paint will be applied at the beginning of the paint spraying stroke. The same will happen at the end of the paint spraying stroke.
- Overlap the spray pattern for an even coat of paint. Typically more paint is delivered to the center of the spray pattern than the edges. To achieve an even application of paint overlap each pass slightly. Usually one-third overlap is enough.
The typical home has many different angles or types of surfaces and each one will present its own challenges. This is where the exceptions come from.
For lap siding, both wood or masonite, spray several rows back and forth at a time working down the wall. Back rolling is recommended to push the paint into nail heads and fully seal the lip of the siding. The spray gun can be angled toward the siding lip to help build up extra primer or paint while back rolling. Back rolling is only necessary on the first coat.
Heavily textured surfaces need the paint applied very thick and immediately rolled behind the sprayer. Spray painting can’t adequately fill pores on stucco or concrete block. It also helps to spray using different angles. This will distribute enough paint around the heavy texture of some stucco’s.
Another consideration is spray painting “dental work” on Victorian homes. This wood trim will have to be sprayed from different angles in order to be properly painted. Use two light misting coats by moving faster and from a greater distance than normal. Spray from one direction first allowing the paint to dry before spraying from the opposite direction.
- Use spray shields wile spraying next to roofs or any other difficult areas. These shields are available in aluminum with a wood handle or cardboard that locks to a special handle.
- If you stop spraying for an hour or two set the airless sprayer and in the shade. Cover the paint with a cloth and submerge the tip end of the gun in the appropriate thinner, water or mineral spirits.
- The sprayer must be properly cleaned if you plan on stopping over night.