To keep your house looking clean and spiffy, you will need to clean and re-paint the aluminum siding from time to time. Painting is a more cost-effective option compared to replacing the siding. If aluminum siding is not painted well, you will find your new coat of paint starting to peel after a few months. These steps will help to ensure the preparation and paint job is properly carried out.

Preparing the aluminum siding

A critical step in painting the aluminum siding is to first make sure the surface is thoroughly clean and dry. Often the old paint on the siding will rub off as a chalky residue, a sign of oxidation of the paint. You may also notice black areas that have been affected by mildew.

Prepare a cleaning solution consisting of one cup each of chlorine bleach and trisodium phosphate (TSP) mixed in a gallon of water. The bleach will kill the mildew, and the TSP is a strong household cleaner that will break down the powdery paint residue. Use an abrasive sponge to scrub the siding clean. You can reach more difficult areas with a scrubbing pad attached to a pole sander. After thorough scrubbing, rinse the surface down using a hose.

Alternatively, you may choose to use a pressure washer to do the cleaning. Using the same cleaning solution, it can do a faster job over a large surface area. Keep the tip of the spray fairly close to the siding and always direct the water downwards. Be very careful that the water does not get behind the siding, especially at corners, doorways, and windows, causing leaks into the house. Rinse off the cleaning solution with clean water. It is expected that some of the old paint will be washed off as well.

Applying primer

The clean aluminum siding should be allowed to dry for several days. The next step is to apply a coat of primer, which will help the new paint to go on smoother and last longer. The type of primer best recommended is an oil-based metal primer. Thin the primer down by adding one pint of paint thinner to a gallon of primer. You may also want to tint the primer so that it is a shade closer to your top coat of paint.

You should not use a primer or a paint that contains ammonia or you will cause a chemical reaction, resulting in the production of a gas. The problem shows up as a formation of bubbles beneath the paint, which will eventually cause peeling.

Applying paint

High quality 100% acrylic latex paint for house exteriors works best for aluminum siding. The paint should be applied within 48 hours of applying the primer. You can use a brush, roller, or rent an airless sprayer suited to thicker latex paint. Take note of the weather when deciding when to complete your paint job. The paint needs to dry slowly, so sunny or windy days are not ideal for applying the paint.