Clean light stains, including dirt, from the siding by mixing 1/2 cup of tri-sodium phosphate with a gallon of hot water in a bucket. Lightly scrub the siding with a soft-bristle brush, starting at the bottom of the wall, working upward. Thoroughly rinse the siding immediately with clean water to prevent staining.
Remove rust stains from the siding by dissolving one part of sodium citrate in six parts of commercial glycerin in a large bucket. Mix the solution with inert dry clay to form a soft, moist mixture, and then apply a thick layer on the rust stains with a trowel. When the paste is dry, replace with fresh paste.
Patch hairline cracks in the siding by working clear epoxy into cracks with a thin object. Repair slightly larger cracks by mixing cement and water to form a grout, and then apply the grout into the crack with a trowel.
Remove efflorescence deposits, a form of crystalline growth, from the asbestos siding by first dry-brushing the area with a soft-bristle brush. Wipe down the wall with a wet sponge or brush.