Painting aluminum siding is a similar process as painting many other types of siding found on homes insofar as it requires the same fundamental steps for a proper paint job:
The first step is to provide a surface that is free from contaminants and otherwise ready for primer. The next step is to apply a coat of primer that is suitable for aluminum (the right kind of primer). The final step is to use a quality exterior acrylic latex paint for the painted finish.
Over a prolonged period of time, aluminum siding can collect contaminants such as dirt, grime, and mildew. Oxidization can also cause aluminum surfaces to become chalky. A good cleaning solution coupled with scrubbing action and/or pressure washing will most likely remove these types of contaminants. Simple Green House & Siding Cleaner is a non-toxic, biodegradable concentrate that works well for aluminum siding. Laundry detergent, about ¼ cup per gallon of water is also an effective cleaning solution. There are actually several cleaning products on the market that could be used to clean weathered aluminum siding.
Begin the cleaning process by waterproofing all the electrical outlets. This can be accomplished with painter’s plastic and red vinyl duct tape. Apply the cleaning solution with a soft to medium bristle scrub brush. A scrub brush that can be attached to a telescoping extension pole increases reach and leverage making it easier to work from the ground. The use of a scouring pad placed on a pole sander head, attached to an extension pole is also a very effective way to eliminate chalky surfaces. After scrubbing a small section, thoroughly rinse with clean water. A garden hose with a nozzle will work. A pressure washer with the wide angle cleaning tip may be preferable for extremely chalky surfaces. The high pressure water helps to remove any contaminants that the scrubbing may have missed. Allow the aluminum siding to thoroughly dry, two or more days before applying a prime coat.
Choosing the Proper Primer and Paint
When painting aluminum siding, success greatly depends on a primer coat that will adhere well to the aluminum surface. The use of a primer that does not bond well to metal surfaces will ultimately cause paint failure for the subsequent finish coats. Some experts claim that only oil base primer formulated for aluminum should be used. They state that the ammonia contained in many latex primers will chemically react with aluminum ultimately causing paint failure. Actually there are many waterborne all purpose primers that work well on aluminum surfaces. Their ease of use and superior adhesion qualities make them a better choice. I have had great success using Stix acrylic urethane primer and ICI Gripper on aluminum surfaces. Rust-oleum also makes a quality latex aluminum primer. One coat of primer should be sufficient for this application.
An all-purpose exterior acrylic latex paint should be used for the finish coats. Because acrylic paint finishes are quite flexible, they perform better when subjected to expansion and contraction than their brittle oil base counterparts. The use of high quality paint will maximize longevity. One finish coat may be sufficient but two finish coats may increase the durability and longevity of the paint job.
aluminum siding is similar to painting other types of residential siding
insofar as paint application. Primer and paint coats can be applied with a
paint brush and roller or they can be spray painted with an airless sprayer.
A 3 or 3-1/2 inch paint brush with synthetic filaments (bristles) is a good choice for a brush finish. A combination nylon/polyester brush works well for this application. A quality brush finish requires maintaining a wet edge during application so as to avoid unsightly lap marks. This is best accomplished by painting one section at a time. Start at the beginning of a section and efficiently work toward the opposite side while maintaining a wet edge. If a paint roller is needed, a mini roller with a short nap roller sleeve is preferable to maintain a relatively smooth finish.
Spray painting aluminum siding can be a big time saver but it does require adequate masking and covering to prevent overspray. Because aluminum siding is a smooth, non-porous material, it is advantageous to control the paint output so as to avoid excessive paint build up. This can be accomplished by choosing the proper airless spray tip. We often use a 515 or 615 reversible spray tip. A 513 or 613 spray tip will also work well but may require a small amount thinning to reduce the viscosity of the paint. A spray tip larger than a 015 may result in paint runs. As with a brush and/or roller finish it is best to start at the beginning of a section and efficiently work toward the opposite side while maintaining a wet edge.