kaolin
kaolinic, adj.
/kay"euh lin/, n.
a fine white clay used in the manufacture of porcelain.
Also, kaoline.
[1720-30; < F < Chin (Wade-Giles) Kao1ling3, (pinyin) Gaoling mountain in Jiangxi province that yielded the first kaolin sent to Europe (gao high + ling hill)]

* * *

clay
also called  china clay 

      soft white clay that is an essential ingredient in the manufacture of china and porcelain and is widely used in the making of paper, rubber, paint, and many other products. Kaolin is named after the hill in China (Kao-ling) from which it was mined for centuries. Samples of kaolin were first sent to Europe by a French Jesuit missionary around 1700 as examples of the materials used by the Chinese in the manufacture of porcelain.

      In its natural state kaolin is a white, soft powder consisting principally of the mineral kaolinite, which, under the electron microscope, is seen to consist of roughly hexagonal, platy crystals ranging in size from about 0.1 micrometre to 10 micrometres or even larger. These crystals may take vermicular and booklike forms, and occasionally macroscopic forms approaching millimetre size are found. Kaolin as found in nature usually contains varying amounts of other minerals such as muscovite, quartz, feldspar, and anatase. In addition, crude kaolin is frequently stained yellow by iron hydroxide pigments. It is often necessary to bleach the clay chemically to remove the iron pigment and to wash it with water to remove the other minerals in order to prepare kaolin for commercial use.

      When kaolin is mixed with water in the range of 20 to 35 percent, it becomes plastic (i.e., it can be molded under pressure), and the shape is retained after the pressure is removed. With larger percentages of water, the kaolin forms a slurry, or watery suspension. The amount of water required to achieve plasticity and viscosity varies with the size of the kaolinite particles and also with certain chemicals that may be present in the kaolin. Kaolin has been mined in France, England, Saxony (Germany), Bohemia (Czech Republic), and in the United States, where the best-known deposits are in the southeastern states.

      Approximately 40 percent of the kaolin produced is used in the filling and coating of paper. In filling, the kaolin is mixed with the cellulose fibre and forms an integral part of the paper sheet to give it body, colour, opacity, and printability. In coating, the kaolin is plated along with an adhesive on the paper's surface to give gloss, colour, high opacity, and greater printability. Kaolin used for coating is prepared so that most of the kaolinite particles are less than two micrometres in diameter.

      Kaolin is used extensively in the ceramic (traditional ceramics) industry, where its high fusion temperature and white burning characteristics makes it particularly suitable for the manufacture of whiteware (china), porcelain, and refractories. The absence of any iron, alkalies, or alkaline earths in the molecular structure of kaolinite confers upon it these desirable ceramic properties. In the manufacture of whiteware the kaolin is usually mixed with approximately equal amounts of silica and feldspar and a somewhat smaller amount of a 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 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.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Kaolin — Kaolin, auch als Porzellanerde, Porzellanton, weiße Tonerde, Aluminiumsilikat oder in der Apotheke als Bolus Alba oder Pfeifenerde bezeichnet, ist ein feines, eisenfreies, weißes Gestein, das als Hauptbestandteil Kaolinit, ein… …   Deutsch Wikipedia

  • kaolin — [ kaɔlɛ̃ ] n. m. • 1739; kao lin 1712; chin. kaoling, proprt « colline élevée », n. du lieu où l on extrayait le kaolin ♦ Silicate d alumine pur, provenant de l altération ( oukaolinisationn. f.) des feldspaths, des granits, argile réfractaire… …   Encyclopédie Universelle

  • Kaolin — (Kaolinit, Porzellanerde, Argillit, China clay) H2Al2Si2O9, reinster Ton, kristallisiert nach Miers monoklin, nach Reusch triklin in sehr kleinen durchsichtigen sechsseitigen Täfelchen oder Blättchen, ähnlich dem Glimmer. Die Blättchen spalten… …   Lexikon der gesamten Technik

  • kaolin — china clay, 1727, from Fr. kaolin (1712), from Chinese Kao ling, transliteration of the name of a mountain in Jiangxi, China (near which it was originally dug up), from Chinese gao high + ling mountain, hill …   Etymology dictionary

  • Kaolin — Ka o*lin, Kaoline Ka o*line, n. [Chin. kao ling.] (Min.) A very pure white clay, ordinarily in the form of an impalpable powder, and used to form the paste of porcelain; China clay; porcelain clay. It is chiefly derived from the decomposition of… …   The Collaborative International Dictionary of English

  • Kaolin — (Mineral), so v.w. Caolin …   Pierer's Universal-Lexikon

  • Kaolīn — (Kaolinit, nach dem chinesischen Kaoling, Porzellanerde), ein natürlich vorkommendes Tonerdesilikat, selten in kleinen, sechsseitigen, tafelförmigen Schüppchen und in feinschuppigen Aggregaten von schneeweißer Farbe (Nakrit) auf Erzgängen… …   Meyers Großes Konversations-Lexikon

  • Kaolin — Kaolīn, Porzellanerde, reinste, weiße, fettige Tonerde, Produkt der Verwitterung des Feldspats und feldspathaltiger Gesteine (Granite, Porphyre), Hauptrohstoff zur Fabrikation des Porzellans …   Kleines Konversations-Lexikon

  • kaòlīn — m 〈G kaolína〉 min. glina bijele boje, služi kao vatrostalna, lončarska, ciglarska i porculanska glina, u medicini kao adsorbens; porculanača ✧ {{001f}}kin …   Veliki rječnik hrvatskoga jezika

  • Kaolin — Kaolin,dasod.der:⇨2Ton …   Das Wörterbuch der Synonyme

  • kaolin — kaòlīn m <G kaolína> DEFINICIJA min. glina bijele boje, služi kao vatrostalna, lončarska, ciglarska i porculanska glina, u medicini kao adsorbens; porculanača ETIMOLOGIJA kin. Kauling: visoki brijeg, naselje u Kini gdje je prvo pronađen +… …   Hrvatski jezični portal

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”