Lightly soiled bricks can be cleaned with water and a wire brush. Each section should be wet down and then scrubbed.
More heavily stained bricks – algae, mold, mildew or rust – require a specific cleaning solution. A good all-purpose solution is a bucket of hot water, 1 cup ammonia, ½ cup of vinegar and 1/4 cup baking soda.
A 50/50 mixture of water and bleach can remove mold and mildew. Soak or spray the bricks with water prior to applying the bleach solution and rinse after to avoid bleach stains.
Gritty hand cleaner works well to remove soot.
Always use safety goggles and gloves and work in a well-ventilated area. Never mix solutions containing ammonia and bleach.
Once you’ve cleaned your brick, use a silicone sealant to preserve and protect it – and prevent you from cleaning it again!