Care and Cleaning of Natural Stone Surfaces

Know your stone

Natural stone cab be classified into two general categories according to its composition: siliceous stone or calcareous stone. Knowing the difference is critical when selecting cleaning products.

Siliceous stone is composed of mainly silica or quartz-like particles. It tends to be very durable and relatively easy to clean with mild acidic cleaning solutions. Types of Siliceous stone include granite, slate, sandstone, quartzite, brownstone, and bluestone

Calcareous stone is composed mainly of calcium carbonate. It is sensitive to acidic cleaning products and frequently requires different cleaning procedures than siliceous stone. Types of calcareous stone include marble, travertine, limestone and Onyx. What may work on Siliceous stone may not be suitable for Calcareous surfaces.

How to tell the difference

A simple acid sensitivity test can be performed whether a stone is Calcareous or Siliceous. You need a few drops of vinegar and an eyedropper. Because the test may permanently etch the stone, select a hidden area (a corner or closet section) and several inches away from the mortar joint. Apply a few drops of vinegar to the surface of the stone on an area about size of a coin. If the stone is calcareous, the vinegar will etch the stone. If little or no reaction occurs, the stone can be considered to be Siliceous.

Rinse the area thoroughly with clean water and wipe dry. This test may not be effective if surface sealers or liquid polishes have been applied to surface. If an old sealer is present, chip a mall piece of the stone away and apply the vinegar to the fractured surface.

Floor Surfaces

Dust mop interior floors frequently using a clean non-treated dust mop. Sand, dirt and grit do the most damage to natural surfaces due to their abrasiveness. Mats or area rugs inside and outside an entrance will help to minimize the sand, dirt and grit that will scratch the stone floor. Be sure that the underside of the mat or rug is a non-slip surface. Normally, it will take a person about eight steps on a floor to remove dirt from the bottom of their shoes.

Other Surfaces

Clean stone surfaces with a few drops of neutral cleaner, stone soap (available at your hardware store or stone dealers) or mild liquid dishwashing detergent and warm water. Do not use products that contain lemon or orange or other acids on marble or other calcareous stones. Use a clean rag mop on floors and a soft cloth on other surfaces. Too much cleaner or soap may leave film and cause streaks. Rinse the surface thoroughly after washing with the soap solution and dry with a soft cloth. Change the rinse water frequently. Do not use scouring powders or creams; these products contain abrasives that may scratch the stone.

Bath and other wet area

To remove soap scum, use a non-acidic soap scum remover or solution of ammonia and water (half cup to a gallon of water). Frequent or over-use of an ammonia solution may dull the surface of the stone.

Vanity top surfaces

Vanity tops may need to have a penetrating sealer applied. Check with your installer for recommendations

Spills and Stains

Blot the spill with a paper towel immediately. Don’t wipe the area, it will spread the spill. Flush the area with plain water and mild soap and rinse several times. Dry the area thoroughly with a soft cloth. Repeat as necessary. If the stain remains, refer to the stain section.

Stain Removal

• Oil based: – (grease, tar, cooking oil, milk, cosmetics) An oil-based stain will darken the stone and normally must be chemically dissolved so the source of the stain can be flushed or rinsed away. Clean gently with a soft, liquid cleanser with bleach or household detergent or ammonia or mineral spirit or acetone. (At no time should these products be mixed!)
• Organic: – (coffee, tea, fruit, tobacco, Paper, food, urine, leaves, bark, bird droppings) May cause a pinkish-brown stain and may disappear after source of the stain has been removed. Outdoors, with the sources removed, normal sunlight and rain action will gently bleach out the stains. Indoors, clean with 12% hydrogen peroxide and a few drops of ammonia
• Biological: – (algae, mildew, lichens, moss, fungi) Clean with dilute (half a cup in a gallon of water) ammonia or bleach or hydrogen peroxide. Do no mix bleach and ammonia. This combination creates a toxic and lethal gas!
• Ink: – (magic marker, pen, ink) Clean with bleach or hydrogen peroxide (light stone only) or lacquer thinner or acetone (dark stones only)