According to Do It Yourself, an effective homemade solution for cleaning aluminum involves mixing up a ratio of 4 cups water to 1 cup vinegar and spraying it onto an aluminum surface that has had lemon slices rubbed directly onto its exterior. This solution brings back the shine and smoothness of aluminum on outdoor surfaces, such as doors, windows and siding.
Other cleaners can be used to wash aluminum siding. Bleach, vinegar and borax are effective cleaning solutions for mold and mildew removal. The aluminum siding should be rinsed before the cleaning solution is applied. Cleaning chemicals then need to be rinsed off to eliminate the possibility of discoloration occurring due to drying.
When homemade cleaning solutions are not effective on tough stains, try specific cleansers, such as trisodium phosphate, and eco-friendly biodegradable options found in hardware stores that are specifically formulated for aluminum siding. This Old House reveals that, no matter the cleaner that is used, aluminum siding should be washed down with water on a hose nozzle's low-pressure setting to prevent damage. Some dirt, grime and mildew may only come off aluminum siding with scrubbing followed by low-pressure water washing.
Other tips for cleaning aluminum siding include spraying water at an angle near windows and doors, using assistance when on a ladder and scrubbing with soft brushes. To keep siding clean, maintain a regular schedule of washing and rinsing the siding each month throughout warm-weather seasons.