Clay theory
Clay is usually formed naturally over a long period of time and usually from the erosion of rocks. It is made of very fine minerals and water but is different from mud because it is plastic. It also hardens when it is fired. It is mainly aluminium silicate but may have other things in it.
When clay is cooked ( fired) in a kiln, permanent chemical changes take place. After it is fired in the kiln it is called ceramic. There are two main categories of clay - earthenware and stoneware. Earthenware describes clay that's correct firing temperature is 1000 degrees. Stoneware is clay that can withstand being fired to 1300 degrees. Stoneware is much stronger than earthenware and also becomes waterproof ( vitrified) when fired to 1300.
Uses
Prehistoric humans discovered the useful properties of clay, and one of the earliest artifacts ever uncovered is a drinking vessel made of sun-dried clay.[citation needed] Depending on the content of the soil, clay can appear in various colors, from a dull gray to a deep orange-red.
Clay tablets were used as the first known writing medium, inscribed with cuneiform script through the use of a blunt reed called a stylus.
Clays sintered in fire were the first form of ceramic. Bricks, cooking pots, art objects, dishware, and even musical instruments such as the ocarina can all be shaped from clay before being fired. Clay is also used in many industrial processes, such as paper making, cement production, and chemical filtering. Clay is also often used in the manufacture ofpipes for smoking tobacco. Until the late 20th century bentonite clay was widely used as a mold binder in the manufacture of sand castings.
Clay, being relatively impermeable to water, is also used where natural seals are needed, such as in the cores of dams, or as a barrier in landfills against toxic seepage (lining the landfill, preferably in combination with geotextiles).[3[[http://en.wikipedia.org/wiki/Clay#cite_note-2|]]]
Recent[when?] studies have investigated clay's absorption capacities in various applications, such as the removal of heavy metals from waste water and air purification.
resources for research on clay:
wikipedia
http://en.wikipedia.org/wiki/Clay
Clay is usually formed naturally over a long period of time and usually from the erosion of rocks. It is made of very fine minerals and water but is different from mud because it is plastic. It also hardens when it is fired. It is mainly aluminium silicate but may have other things in it.
When clay is cooked ( fired) in a kiln, permanent chemical changes take place. After it is fired in the kiln it is called ceramic. There are two main categories of clay - earthenware and stoneware. Earthenware describes clay that's correct firing temperature is 1000 degrees. Stoneware is clay that can withstand being fired to 1300 degrees. Stoneware is much stronger than earthenware and also becomes waterproof ( vitrified) when fired to 1300.
Uses
Prehistoric humans discovered the useful properties of clay, and one of the earliest artifacts ever uncovered is a drinking vessel made of sun-dried clay.[citation needed] Depending on the content of the soil, clay can appear in various colors, from a dull gray to a deep orange-red.
Clay tablets were used as the first known writing medium, inscribed with cuneiform script through the use of a blunt reed called a stylus.
Clays sintered in fire were the first form of ceramic. Bricks, cooking pots, art objects, dishware, and even musical instruments such as the ocarina can all be shaped from clay before being fired. Clay is also used in many industrial processes, such as paper making, cement production, and chemical filtering. Clay is also often used in the manufacture ofpipes for smoking tobacco. Until the late 20th century bentonite clay was widely used as a mold binder in the manufacture of sand castings.
Clay, being relatively impermeable to water, is also used where natural seals are needed, such as in the cores of dams, or as a barrier in landfills against toxic seepage (lining the landfill, preferably in combination with geotextiles).[3[[http://en.wikipedia.org/wiki/Clay#cite_note-2|]]]
Recent[when?] studies have investigated clay's absorption capacities in various applications, such as the removal of heavy metals from waste water and air purification.
resources for research on clay:
wikipedia
http://en.wikipedia.org/wiki/Clay
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