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Fuller's earth is usually highly plastic, sedimentary clays or clay-like earthy material. It is frequently used to decolorize, filter, and purify animal, mineral, and vegetable oils and greases.
Occurrence and composition
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In 2005, the United States was the largest producer of fuller's earth with an almost 70% world share followed at a distance by Japan and Mexico.
Fuller's earth usually has a high magnesium oxide content. In the United States, two varieties of fuller's earth are mined, mainly in the southeastern states. These comprise the minerals montmorillonite or palygorskite (attapulgite) or a mixture of the two; some of the other minerals that may be present in fuller's earth deposits are calcite, dolomite, and quartz.
In England, fuller's earth occurs mainly in the Lower Greensand. It has also been mined in the Vale of White Horse, Oxfordshire, England. The Combe Hay Mine was a fuller's earth mine operating to the south of Bath, Somerset until 1979. Other sites south of Bath included Frome, Lonsdale, Englishcombe, Tucking Mill and Duncorn Hill. Although these sites had been used since Roman times, William Smith developed new methods for the identification of deposits of fuller's earth to the south of Bath. Other English sources include a mine near Redhill, Surrey (worked until 2000), and Woburn, Bedfordshire, where production ceased in 2004.
In some countries calcium bentonite is known as fuller's earth, a term that can also refer to attapulgite, a mineralogically distinct clay mineral that exhibits similar properties.
Hills, cliffs, and slopes that contain fuller's earth can be unstable, since this material can be thixotropic when saturated by heavy rainfall.
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The name reflects the first use of the material. In past centuries, fullers kneaded fuller's earth and water into woollen cloth to absorb lanolin, oils, and other greasy impurities as part of the cloth finishing process. Similarly, it has been used as an ingredient in powdered, "dry" shampoos. It is also an important ingredient of face packs. Fuller's earth was also sold in pharmacies until recently for compressing pills and cleaning hats and fabrics.
Important uses are in absorbents and filters. Because of this, it is used (with activated charcoal) in the treatment of paraquat poisoning to prevent the progression to pulmonary fibrosis. Fuller's earth is also used by military and civil emergency service personnel to decontaminate the clothing and equipment of servicemen and CBRN (Chemical Biological Radiological Nuclear) responders who have been contaminated with chemical agents.
Fuller's earth has also been used extensively for many years in the motion picture industry for a variety of uses. In the area of special effects, it is used in pyrotechnics explosions and dust clouds because it spreads farther and higher than most natural dirt soils resulting in a blast that looks larger. It is also safer than naturally-occurring dirt, should the blast spray hit actors. Fuller's earth is also widely used by the make-up, props, wardrobe, and set dresser departments because it is considered a "clean" dirt, safer to use around people, and it cleans up easily. However, the health issues in this regard have been debated recently. Fuller's earth is available in small quantities by make-up suppliers for use in making the face and body appear dirty. It is used by props technicians in a flour sieve to make furniture look dusty. Wardrobe dressers use a small, loose-mesh cloth bag filled with fuller's earth to dust down clothing to make it look more worn or dusty, as in the case of cowboys out on the range, or soldiers on the battle field. Set dressers use fuller's earth to change paved streets into dirt roads, to create dust trailing from a moving vehicle over a dirt road, or to indicate a vehicle trail over untraveled ground.
- A. B. Hawkins, M. S. Lawrence and K. D. Privett (September 1986). "Clay Mineralogy and Plasticity of the Fuller's Earth Formation Bath, UK". Clay Minerals (The Mineralogical Society) 21 (3): 293–310. doi:10.1180/claymin.1986.021.3.04. Retrieved 2009-09-05.
- Mineral statistics of the United Kingdom of Great Britain and Ireland, 1855
- Macmillen, Neil (2009). A history of the Fuller's Earth mining industry around Bath. Lydney: Lightmoor Press. p. 9. ISBN 978-1-899889-32-7.
- Gray Cross Prescription Purity Fuller's Earth "Uses: Used for cleaning hats and fabrics" Rabin Company, Los Angeles, USA, circa 1958
- Survive to Fight, British Army CBRN Publication, 2008
- "Mineral Fact Sheet: Fuller's Earth". British Geological Survey. Retrieved 7 August 2009.
- "fuller's earth". Encyclopædia Britannica. Encyclopædia Britannica Online. 2006. 9035638. Retrieved 2006-11-02.
- Oxford English Dictionary (2nd ed.). Oxford: Oxford U P. 1989.
- Brady, G.S., Clauser, H.R., & Vaccari, J.A. (2002). Materials handbook. (15th ed.) New York: McGraw-Hill.
- Hosterman, J.W. and S.H. Patterson. (1992). Bentonite and Fuller's earth resources of the United States [U.S. Geological Survey Professional Paper 1522]. Washington, D.C.: United States Government Printing Office.