Enter your search terms Submit search form

(Continuing to: Natural Stone">Stone Care and Cleaning)

Know Your Stone">Stone
Natural stone">stone can be classified into two general categories according to its composition: siliceous stone">stone or calcareous stone">stone. Knowing the difference is critical when selecting cleaning products.

Siliceous stone">stone is composed mainly of 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">stone include granite, slate, sandstone">stone, quartzite, brownstone">stone and bluestone">stone.

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

How to Tell the Difference
A simple acid sensitivity test can be performed to determine whether a stone">stone is calcareous or siliceous. You will need about 4 oz. of a 10%solution of muriatic acid and an eye-dropper. Or you can use household vinegar and an eyedropper. Because this test may permanently etch the stone">stone, select an out of the way area(a corner or closet) and several inches away from the mortar joint. Apply a few drops of the acid solution to the stone">stone surface on an area about the size of a quarter. If the stone">stone is calcareous, the acid drops will begin to bubble or fizz vigorously. If little or no reaction occurs, the stone">stone can be considered 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. If an old sealer is present, chip a small piece of stone">stone away and apply the acid solution to the fractured surface. CAUTION: Muriatic acid is corrosive and is considered to be a hazardous substance. Proper head and body protection is necessary when acid is used.

source: Marble Institute of America