Kaolin is the common name for the mineral kaolinite, a chalky aluminosilicate mineral formed by the weathering of harder aluminosilicates such as feldspar. It is also known as china clay and is the chief source of most modern porcelain. It can be white or shaded with pink or russet tones depending on the impurities that are present. It is named for a town in China near which the mineral is found and is a very common mineral that is mined in many areas of the world. This versatile mineral is found in many industries and some of the uses of kaolin besides as clay for pottery and porcelain are paper-making, paint manufacture, and cosmetics.
The manufacture of ceramics has historically been among the chief uses of kaolin, which is still the main component of most ceramic products, including stoneware and porcelain. Pure white kaolin is especially favored for these products because of its color, although natural-colored kaolin is used as well. Another of the uses of kaolin is in the manufacture of specialty ceramic products called refractories, which are used in making kilns and ovens and to line furnaces in foundries.
In modern times, paper-making has become one of the largest uses of kaolin. Kaolin is infused into paper products to improve its white color, opacity, and ability to hold ink. It also improves print quality and makes the finish of paper smoother. Many glossy papers contain a substantial amount of kaolin, which may be infused into the paper with special adhesives. Many types of paper can contain as much as 70% kaolin by weight, and most of the kaolin produced worldwide is used by the paper industry.
Many other industries use kaolin as well. The mineral is used to supplement titanium oxide as a white coloring agent in many products. It is used in some paints, inks, and pigments, particularly in white shades. Kaolin is used in some kinds of rubber as well, which benefits from increased toughness and resistance to wear. Some types of mortar and Portland cement also contain kaolin, which improves the ability of these materials to absorb moisture evenly.
Medical applications are another traditional and ongoing use of kaolin. It has been used for centuries as a remedy for diarrhea and nausea, and some modern products continue to use it as an ingredient. Kaolin infused gauze, which has a greatly improved ability to staunch blood flow from wounds, was developed recently by the US Naval Medical Research Institute. Kaolin is used as an ingredient in cosmetics, pharmaceuticals, and foods as well, particularly in products like toothpaste. It can also be used in organic farming, both to repel insects and to prevent sun damage.