The constitution, evaluation and ceramic properties of ball clays

Ball clay is a fine-grained highly plastic, mainly kaolinitic, sedimentary clay, the higher grades of which fire to a white or near white colour. The paper will review the origin of the term "Ball Clay" and the location and origins of several deposits with particular emphasis on the mineralogical, physical and rheological properties which make the clays so important in ceramics bodies. Particular attention will be paid to the well known bay clay deposits of Devon and Dorset in southwest England, which are mined by ECC International Europe and Watts Blake Bearne & Company PLC, and brief descriptions from elsewhere in the world of ball clays from the United States, Germany, Czech Republic, Thailand, Indonesia, Argentina and China. The evaluation of deposits will be covered along with a description of the main types of ball clay for ceramics with details of the mining, processing and blending techniques which are necessary to ensure long term consistency of products. A brief description in given of the ceramic properties of some Brazilian ball clays. The location of some ball clay deposits is shown in Fig. 1.