Sandstone can be cleaned by manually scrubbing it with a brush and cleaning agent, or it can be washed with a pressure washer. The type of cleaner that should be used depends on the composition of the sandstone.
Calcareous sandstone may be cleaned with an alkaline cleaner that contains potassium hydroxide. Noncalcareous sandstone should be cleaned using hydrofluoric acid-based cleaner.
Before the sandstone is cleaned, all hardware attached to it must be removed. If a pressure washer is to be used, it should not spray more than 800 psi when used on medium. This prevents the sandstone from being degraded and eroded over time.
Ideally, sandstone should be cleaned at regular intervals. Owners should not wait until it is filthy to give sandstone a good cleaning. Prevention can help preserve the sandstone and keep it looking its best.