Things You'll Need
Commercial concrete cleaner
Cast stone is often used as an ornamental masonry product. The stones are used in buildings, fireplace and fountains to add an architectural look to the structure. It is common to have dirt and stains accumulated on the cast stone over a period of time. The cast stone can be cleaned, but requires extra caution.
Cover the doors and windows next to the cast stone to avoid damage from the acid in the cleaner.
Use the hose to spray the cast stone with water. Use a soft brush to apply water to the hard to reach architectural trims. It is very important to wet the surface with water first as it prevents the surface from etching when using the cleaner.
Wear rubber gloves and apply the cleaner to a small area carefully. Do not apply the solution to joints that are open or have sealants. It could lead to corrosion over a period of time. Leave the solution on the cast stone for a minute. Use a soft brush to rub stubborn stains.
Clean the surface thoroughly with water. Acids left behind will cause corrosion. Repeat step 4 and step 5 if necessary.
Cast stone will take several days to dry.
Do not use a metal brush. Do not use power washing or sandblasting techniques for cleaning cast stone.