Editing Clay (section)

== Uses ==
[[File: Clay In A Construction Site.jpg|thumb|Clay layers in a construction site in [[Auckland]], New Zealand. Dry clay is normally much more stable than sand in excavations.]]
[[File:Diósgyőr - 2015.02.07 (145).JPG|thumb|upright|left|A 14th-century [[Stopper (plug)|bottle stopper]] made of [[fire clay|fired clay]]]]
[[Modelling clay]] is used in art and handicraft for [[sculpting]].
Clays are used for making [[pottery]], both utilitarian and decorative, and construction products, such as bricks, walls, and floor tiles. Different types of clay, when used with different minerals and firing conditions, are used to produce earthenware, stoneware, and porcelain. Prehistoric humans discovered the useful properties of clay. Some of the earliest pottery shards recovered are from central [[Honshu]], [[Japan]]. They are associated with the [[Jōmon period|Jōmon]] culture, and recovered deposits have been [[radiocarbon dating|dated]] to around 14,000&nbsp;BCE.{{sfn|Scarre|2005|p=238}} Cooking pots, art objects, dishware, [[smoking pipe (tobacco)|smoking pipes]], and even [[musical instrument]]s such as the [[ocarina]] can all be shaped from clay before being fired. 

Ancient peoples in [[Mesopotamia]] adopted clay tablets as the first known writing medium.{{sfn|Ebert|2011|p=64}} Clay was chosen due to the local material being easy to work with and widely available.<ref>{{Cite web |title=British Library |url=https://www.bl.uk/history-of-writing/articles/a-brief-history-of-writing-materials-and-technologies#:~:text=The%20earliest%20material%20used%20to,drawn%20into%20with%20a%20stylus. |access-date=2023-05-09 |website=www.bl.uk |archive-date=12 September 2022 |archive-url=https://web.archive.org/web/20220912141816/https://www.bl.uk/history-of-writing/articles/a-brief-history-of-writing-materials-and-technologies#:~:text=The%20earliest%20material%20used%20to,drawn%20into%20with%20a%20stylus. |url-status=dead }}</ref> Scribes wrote on the tablets by inscribing them with a script known as [[cuneiform]], using a blunt [[reed (plant)|reed]] called a [[stylus]], which effectively produced the wedge shaped markings of their writing. After being written on, clay tablets could be reworked into fresh tablets and reused if needed, or fired to make them permanent records. Nowadays, clay is added as a filler to [[graphite]], in pencil lead, to change the hardness and blackness of the [[pencil]]. Purpose-made clay balls were used as [[sling (weapon)#Ammunition|sling ammunition]].{{sfn|Forouzan|Glover|Williams|Deocampo|2012}} Clay is used in many industrial processes, such as [[paper]] making, [[cement]] production, and chemical [[filter (chemistry)|filtering]].{{sfn|Nesse|2000|p=257}} [[Bentonite]] clay is widely used as a mold binder in the manufacture of [[sand casting]]s.{{sfn|Boylu|2011}}{{sfn|Eisenhour|Brown|2009}}
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[[File:Bain d'argile à Gogotinkpon au Bénin 01.jpg|thumb|Clay bath near [[lake Ahémé]] in [[Benin]]]]

=== Materials ===

Clay is a common filler used in polymer [[nanocomposites]].  It can reduce the cost of the composite, as well as impart modified behavior: increased [[stiffness]], decreased [[Permeation|permeability]], decreased [[electrical conductivity]], etc.<ref>{{cite journal |last1=Kotal |first1=M. |last2=Bhowmick |first2=A. K. |title=Polymer nanocomposites from modified clays: Recent advances and challenges |journal=Progress in Polymer Science |date=2015 |volume=51 |pages=127–187 |doi=10.1016/j.progpolymsci.2015.10.001}}</ref>

=== Medicine ===
Traditional uses of [[medicinal clay|clay as medicine]] go back to prehistoric times. An example is [[Armenian bole]], which is used to soothe an upset stomach. Some animals such as parrots and pigs ingest clay for similar reasons.{{sfn|Diamond|1999}} [[Kaolin|Kaolin clay]] and [[attapulgite]] have been used as anti-diarrheal medicines.{{sfn|Dadu|Hu|Cleeland|Busaidy|2015}}

=== Construction ===
[[File:WMEE-exp2019-(113).jpg|thumb|left|A clay building in [[South Estonia]]]]
Clay as the defining ingredient of [[loam]] is one of the oldest [[building material]]s on [[Earth]], among other ancient, naturally occurring geologic materials such as stone and organic materials like wood.{{sfn|Grim|2016}} {{cn span|date=December 2020|Between one-half and two-thirds of the world's population, in both traditional societies as well as developed countries, still live or work in buildings made with clay, often baked into brick, as an essential part of their load-bearing structure.}} Also a primary ingredient in many [[natural building]] techniques, clay is used to create [[adobe]], [[cob (material)|cob]], [[cordwood]], and structures and building elements such as [[wattle and daub]], clay plaster, clay render case, clay floors and clay [[paints]] and [[ceramic building material]]. Clay was used as a [[mortar (masonry)|mortar]] in brick [[chimneys]] and stone walls where protected from water.

Clay, relatively [[permeability (fluid)|impermeable]] to water, is also used where [[Puddling (civil engineering)|natural seals]] are needed, such as in pond linings, the cores of [[dam]]s, or as a barrier in [[landfill]]s against toxic seepage (lining the landfill, preferably in combination with [[geotextile]]s).{{sfn|Koçkar|Akgün|Aktürk|2005}} Studies in the early 21st century have investigated clay's [[sorption|absorption]] capacities in various applications, such as the removal of [[heavy metals]] from waste water and air purification.{{sfn|García-Sanchez|Alvarez-Ayuso|Rodriguez-Martin|2002}}{{sfn|Churchman|Gates|Theng|Yuan|2006}}