DO NOT use muriatic acid on cast stone as it can burn and/or stain, as well as leach organic and inorganic particles to the surface of the stone.

Using a soft bristle brush and a mild solution of water and hydrochloric acid (six to one respectively) with a small amount of liquid dishwashing detergent will allow the stone's surface to be cleaned without being etched. Smaller brushes such as a toothbrush or similar may be required to clean inside corners or detailed areas.

Take necessary steps to protect surrounding areas that may come in contact with the cleaner. Soak the stone with water prior to washing with the acid solution to prevent surface burning. Insure that lower stone courses are frequently drenched with water because as acid is rinsed down the wall it can gather strength when reapplied.

Allowing the detergent to dry on the surface may result in stains and residue. Using fresh water, thoroughly rinse the stone's surface to remove any chemical residue or free sand immediately after cleaning and before it is allowed to dry. Do not allow the cleaner to remain on the grout joints any longer than is absolutely necessary, as they are much more vulnerable to discoloration and deterioration when exposed to acids.

If the stone has stubborn stains that are not effected by the 6:1 solution, contact our office for assistance. When unusual stains are encountered, the same procedures which are recommended to clean concrete will normally clean Cast Stone. The most important step to stain removal is identifying the stain and its cause. There are degreasers and paint removers readily available. Any treatment should be tested on a small inconspicuous area prior to cleaning the main units.

Helpful Hints:

• The stronger the solution, and/or the longer the solution is allowed to set on  the surface 
  of the stone, the rougher the finish of the stone will become.

• Metal fiber brushes are not to be used for scrubbing Cast Stone.

• Cast Stone must be thoroughly dry before applying a sealer to the  finished surfaces.