Ball clay

File:Image 8-ball clay.jpg

Ball Clay

Description

A fine, soft, very plastic clay. Ball clay is a relatively pure, Secondary clay composed of Kaolin (20-90%), Mica (5-45%), and Quartz (1-70%). The high quality clay is found in England (Wareham, Dorset, Devon) and the U.S. (Kentucky, Tennessee). Originally, ball clay was dug up and made into 30-35 pound balls for transportation by horses. The fine-grain clay contains small amounts of carbon and other organic materials that give it an intial dark color. These materials are combusted during firing leaving a white vessel. Ball clay is very plastic and has a high shrinkage rate of up to 20 %. It is often mixed with other clays to increase their plasticity. Ball clay is used in the manufacture of ceramics, whiteware, porcelain, glass, and tiles.

Synonyms and Related Terms

argile plastique (Fr.); argila gorda (Port.)

Sources Checked for Data in Record

• G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 428

• Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)

• Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993

• Henry Hodges, Artifacts: An Introduction to Early Materials and Technology, Ronald P. Frye, Kingston, Canada, 1988

• Robert Fournier, Illustrated Dictionary of Practical Pottery, Chilton Book Company, Radnor, PA, 1992

• Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997

• The Dictionary of Art, Grove's Dictionaries Inc., New York, 1996 Comment: "Ceramics"

• Art and Architecture Thesaurus Online, http://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000