Kaolin

Kaolin is used extensively in the ceramic industry, where its high fusion temperature and white burning characteristics make it particularly suitable for the manufacture of whiteware (china), porcelain, and refractories. The absence of any iron, alkalies or alkaline piles of earth in the molecular structure of kaolinite confers upon it these desirable ceramic properties. In the manufacture of whitewater, the kaolin is usually mixed with approximately equal amounts of silica and feldspar and a somewhat smaller amount of plastic light-burning clay known as ball clay. These components are necessary to obtain the proper properties of plasticity, shrinkage, vitrification, etc., for forming and firing the ware. Kaolin is generally used alone in the manufacture of refractories.

Substantial tonnages of kaolin are used for filling rubber to improve its mechanical strength and resistance to abrasion. For this purpose, the clay used must be extremely pure kaolinite and exceedingly fine-grained. Kaolin is also used as an extender and flattening agent in paints. It is frequently used in adhesives for a paper to control the penetration into the paper. Kaolin is an important ingredient in ink, organic plastics, some cosmetics, and many other products where its very fine particle size, whiteness, chemical inertness, and absorption properties give it particular value.