Combining brick and siding on a home's exterior looks nice but can cause a few extra maintenance chores for the homeowner. The white chalky film that sits on your brick, right next to the aluminum siding is oxidation. Aluminum siding, when exposed to air, will oxidize and form a white powder-like substance on the surface of the siding. This oxidation is often transferred to the brick that surrounds the siding. Remove this oxidation with the proper chemicals and some hard work and your brick will look as good as new.
Rinse the stained area with a hose to remove large pieces of dirt and debris.
Mix one part bleach with one part water. Dip a sponge into the solution and apply it to the stain. Let the bleach and water sit on the stain for 15 minutes.
Scrub the stained area thoroughly. Choose a synthetic bristled brush. Steel or metal brushes will damage the brick. You can remove most of the oxidation with heavy pressure and scrubbing. If the oxidation is not completely removed, continue to Step 4.
Put on rubber gloves. Mix 1 lb. oxalic acid with 1 gallon of water. Put a small amount of the solution on a brick to test the effects. Let the solution sit for 15 minutes. Remove with clean water. If the brick is not stained or damaged, proceed to Step 5.
Apply the oxalic acid solution to all of the oxidation. Let the solution sit on the brick for 5 minutes. Rinse with a garden hose to remove all chemicals.