Magic Sand

    Kids, have you ever built a sand castle at the beach? The sand "wets" easily with water to make a nice packing mud. Beach sand is mostly made of the mineral quartz (a form of silica, SiO2) that is broken into tiny pieces. In the jargon of chemistry, the surface of sand is said to be hydrophilic, or water-loving. But there is another type of sand that behaves very differently. "Magic" sand is coated with even smaller particles of chemically treated silica. This special surface treatment makes the sand hydrophobic, or water-hating. So what does this mean? Instead of sinking in water like beach sand, magic sand will float. A thick layer of magic sand will eventually sink, but it is surrounded by a silvery layer that is actually an air pocket. The clump can be molded underwater into any desired shape by hand. When taken back out of water, these sand grains are not clumped and are perfectly dry!

    Magic sand was developed by chemists at Cabot Corp. with the idea that it could be used to cleanse water of oily contamination. Many materials that are water-hating, like magic sand, are oil-loving. When sprinkled on an oil slick, magic sand attaches to the oil, adds weight, and sinks. This theoretically allows oil to be dredged from the bottom and saves the coasts from an oil slick. It has also been tested by utility companies in the Arctic. When a junction box is covered with magic sand, buried lines can be serviced easily because the dirt does not freeze and remains dry and loose year round. Other proposed uses: a surface for horse-racing tracks, in golf course sand traps, in children's sandboxes, and around the foundations of homes.

    There is a product available in toy stores called Sqand (RoseArt), for ages 6+, that is based on the principle of magic sand if you would 

    Please note:  All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.



    Kathleen Carrado Gregar, PhD, Argonne National Labs 
    [email protected]
    April 1998


    Reference: ChemMatters, April 1994, "Magic Sand" by D. Robson.