Aluminum siding is a common exterior home covering that lasts for many years with little maintenance other than cleaning. However, as it ages, the metal oxidizes and creates a white chalky residue on the siding that dulls it. If the siding is located next to a brick surface, the white oxidation can run down and stain the bricks as well. It is best to remove the white stains as soon as they occur.
Fill a bucket with 1 gallon of warm water and 2 to 3 tbsp. of liquid dish soap. Stir the mixture up until soap bubbles form.
Put on rubber gloves and insert an abrasive sponge into the bucket until saturated. Scrub the brick surface with the sponge to remove as much of the stain as possible. Rinse off the soap residue.
Scrub the remaining residue with a piece of steel wool or a wire brush using circular motions to dislodge the remaining residue.
Put on heat-resistant gloves and plug in a heat gun. Turn the heat gun to high heat and aim the nozzle at the remaining stains on the brick surface. Keep the heat gun at least 12 inches from the brick and use care since the heat will cause severe burns on the skin.
Turn the heat gun off and scrape the brick again with the wire brush to dislodge any remaining oxidation.
Open the tank of a pressure washer and fill it with a mix of concrete cleaner and water, using the proportions specified on the cleaner bottle. Put on safety glasses and pressure wash the brick surface to complete the stain removal process.