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34-435: In the great majority of cases the "red" concerned is the natural reddish-brown of the fired clay , and the same sort of colour as in terracotta (which most types of red ware could also be called) or red brick. The colour to which clay turns when fired varies considerably with its geological makeup and the conditions of firing, and as well as terracotta red, covers a wide range of blacks, browns, greys, whites and yellows. Of

68-575: A gel of orthosilicic acid ).) The clay minerals formed depend on the composition of the source rock and the climate. Acid weathering of feldspar -rich rock, such as granite , in warm climates tends to produce kaolin. Weathering of the same kind of rock under alkaline conditions produces illite . Smectite forms by weathering of igneous rock under alkaline conditions, while gibbsite forms by intense weathering of other clay minerals. There are two types of clay deposits: primary and secondary. Primary clays form as residual deposits in soil and remain at

102-836: A great capacity to take up water, and they increase greatly in volume when they do so. When dried, they shrink back to their original volume. This produces distinctive textures, such as mudcracks or "popcorn" texture, in clay deposits. Soils containing swelling clay minerals (such as bentonite ) pose a considerable challenge for civil engineering, because swelling clay can break foundations of buildings and ruin road beds. Clay minerals most commonly form by prolonged chemical weathering of silicate-bearing rocks. They can also form locally from hydrothermal activity. Chemical weathering takes place largely by acid hydrolysis due to low concentrations of carbonic acid , dissolved in rainwater or released by plant roots. The acid breaks bonds between aluminium and oxygen, releasing other metal ions and silica (as

136-402: A major challenge in civil engineering . The defining mechanical property of clay is its plasticity when wet and its ability to harden when dried or fired. Clays show a broad range of water content within which they are highly plastic, from a minimum water content (called the plastic limit ) where the clay is just moist enough to mould, to a maximum water content (called the liquid limit) where

170-556: A red or terracotta-coloured body. Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Red Polished Ware . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Red_Polished_Ware&oldid=1245636063 " Category : Disambiguation pages Hidden categories: Misplaced Pages articles needing clarification from September 2024 Short description

204-453: A reddish body, whether glazed or not. In fact it was very often given a white or other glaze, either tin-glazed or lead-glazed , though it is more usual to describe them as lead-glazed. Depending on the locality, this was the basic utilitarian pottery of the Colonial period of North America. It was often complemented by imported or American stoneware for large vessels where the added strength

238-481: A special type of clay, came to Holland through the East India companies with tea consignments and provided exemplars which were often copied with various degrees of closeness. Soon a European design vocabulary was used as well. A Delftware manufacturer announced in 1678 that he was making "red teapots", of which no examples are known to survive. The Dutch Elers brothers brought the style to Staffordshire pottery in

272-452: Is Armenian bole , which is used to soothe an upset stomach. Some animals such as parrots and pigs ingest clay for similar reasons. Kaolin clay and attapulgite have been used as anti-diarrheal medicines. Clay as the defining ingredient of loam is one of the oldest building materials on Earth , among other ancient, naturally occurring geologic materials such as stone and organic materials like wood. Between one-half and two-thirds of

306-445: Is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolinite , Al 2 Si 2 O 5 ( OH ) 4 ). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide . Clays develop plasticity when wet but can be hardened through firing . Clay

340-620: Is a unique type of marine clay indigenous to the glaciated terrains of Norway , North America , Northern Ireland , and Sweden . It is a highly sensitive clay, prone to liquefaction , and has been involved in several deadly landslides . 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

374-459: Is clay with visible annual layers that are formed by seasonal deposition of those layers and are marked by differences in erosion and organic content. This type of deposit is common in former glacial lakes . When fine sediments are delivered into the calm waters of these glacial lake basins away from the shoreline, they settle to the lake bed. The resulting seasonal layering is preserved in an even distribution of clay sediment banding. Quick clay

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408-448: Is especially used for pottery from the 17th and 18th centuries, before porcelain , whether imported from East Asia or made in Europe, became cheap enough to be used very widely. In this period red stoneware was used for vessels, especially teapots, jugs and mugs, which were relatively expensive and carefully made and decorated. Chinese Yixing clay teapots , an unglazed stoneware type made from

442-674: Is important to soil fertility. Clay is a common component of sedimentary rock . Shale is formed largely from clay and is the most common of sedimentary rocks. However, most clay deposits are impure. Many naturally occurring deposits include both silts and clay. Clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts , which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in particle size and other physical properties. The distinction between silt and clay varies by discipline. Geologists and soil scientists usually consider

476-429: Is the longest-known ceramic material. Prehistoric humans discovered the useful properties of clay and used it for making pottery . Some of the earliest pottery shards have been dated to around 14,000 BCE, and clay tablets were the first known writing medium. Clay is used in many modern industrial processes, such as paper making, cement production, and chemical filtering . Between one-half and two-thirds of

510-512: Is used in many industrial processes, such as paper making, cement production, and chemical filtering . Bentonite clay is widely used as a mold binder in the manufacture of sand castings . 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 permeability , decreased electrical conductivity , etc. Traditional uses of clay as medicine go back to prehistoric times. An example

544-437: The 1690s, after finding a suitable source of clay, and were widely imitated there. Some red stoneware by rival Dutch potters including Ary de Milde from the years around 1700 does survive, closely copying Yixing pots in style. Johann Friedrich Böttger was in contact with some of these and developed a rival "Böttger ware", a dark red stoneware first sold in 1710, and manufactured and imitated by others, all up to about 1740. It

578-412: The 19th century. But these special decorated pieces are rather untypical of the mass of sherds found by archaeologists excavating sites of the period. Many of these fancy pieces are dated, signed or marked with a stamp. "Red ware" is widely used in archaeology to distinguish local types of red pottery from types with other colours found in the same region. Generally these are unglazed earthenware where

612-415: The cohesion that makes it plastic. In kaolinite clay, the bonding between plates is provided by a film of water molecules that hydrogen bond the plates together. The bonds are weak enough to allow the plates to slip past each other when the clay is being moulded, but strong enough to hold the plates in place and allow the moulded clay to retain its shape after it is moulded. When the clay is dried, most of

646-516: The first known writing medium. Clay was chosen due to the local material being easy to work with and widely available. Scribes wrote on the tablets by inscribing them with a script known as cuneiform , using a blunt 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. Purpose-made clay balls were used as sling ammunition . Clay

680-404: The material. The clay mineral kaolinite is transformed into a non-clay material, metakaolin , which remains rigid and hard if moistened again. Further firing through the stoneware and porcelain stages further recrystallizes the metakaolin into yet stronger minerals such as mullite . The tiny size and plate form of clay particles gives clay minerals a high surface area. In some clay minerals,

714-724: The moulded clay is just dry enough to hold its shape. The plastic limit of kaolinite clay ranges from about 36% to 40% and its liquid limit ranges from about 58% to 72%. High-quality clay is also tough, as measured by the amount of mechanical work required to roll a sample of clay flat. Its toughness reflects a high degree of internal cohesion. Clay has a high content of clay minerals that give it its plasticity. Clay minerals are hydrous aluminium phyllosilicate minerals , composed of aluminium and silicon ions bonded into tiny, thin plates by interconnecting oxygen and hydroxide ions. These plates are tough but flexible, and in moist clay, they adhere to each other. The resulting aggregates give clay

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748-467: The plates carry a negative electrical charge that is balanced by a surrounding layer of positive ions ( cations ), such as sodium, potassium, or calcium. If the clay is mixed with a solution containing other cations, these can swap places with the cations in the layer around the clay particles, which gives clays a high capacity for ion exchange . The chemistry of clay minerals, including their capacity to retain nutrient cations such as potassium and ammonium,

782-570: The red colour is easily visible in complete pieces. Examples of types include: Red Polished Ware , of which there are five main unrelated types, all ancient, from Egypt, India, Cyprus, North Africa, and Roman Europe; the Black and red ware culture of Bronze Age India (individual objects are either black or red); African red slip ware ; Roman "red gloss ware" or Terra sigillata ; Salado or Roosevelt Red Ware , Arizona, c. 1280 to 1450 AD, and one form of Romano-British Crambeck Ware . Clay Clay

816-1177: The removal of heavy metals from waste water and air purification. Red Polished Ware (disambiguation) (Redirected from Red Polished Ware (disambiguation) ) Red Polished Ware may refer to several types of ancient pottery with a red or terracotta-coloured body: Egypt El-Badari , Egypt c. 5500-4000 BCE Cyprus Pottery of ancient Cyprus , Cyprus c. 2000 BCE Philia culture § Pottery , Cyprus c. 2000 BCE India Red Polished Ware in Gujarat and West & North India c. 300 BCE-1000 CE, continued through Kushan (39-375 CE), Gupta (4th to early 6th century CE) and Vardhan period Pushyabhuti dynasty (early 6th century to 7th century CE) periods such as at Harsh Ka Tila in Haryana Post-period, ie. after early 6th century CE Ancient Rome Terra sigillata § Roman red gloss pottery (Samian/samian ware); not capitalized African red slip ware See also [ edit ] Redware - various types of pottery with

850-696: The separation to occur at a particle size of 2 μm (clays being finer than silts), sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Clay-size particles and clay minerals are not the same, despite a degree of overlap in their respective definitions. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits . ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger. Mixtures of sand , silt and less than 40% clay are called loam . Some clay minerals (such as smectite ) are described as swelling clay minerals, because they have

884-841: The site of formation. Secondary clays are clays that have been transported from their original location by water erosion and deposited in a new sedimentary deposit. Secondary clay deposits are typically associated with very low energy depositional environments such as large lakes and marine basins. The main groups of clays include kaolinite , montmorillonite - smectite , and illite . Chlorite , vermiculite , talc , and pyrophyllite are sometimes also classified as clay minerals. There are approximately 30 different types of "pure" clays in these categories, but most "natural" clay deposits are mixtures of these different types, along with other weathered minerals. Clay minerals in clays are most easily identified using X-ray diffraction rather than chemical or physical tests. Varve (or varved clay )

918-599: The two "redware" types, both made between the 17th to 19th centuries (with modern revivals or imitations), the European was unglazed stoneware , mostly for teapots, jugs and mugs, and moderately, sometimes very, expensive. The American redware was cheap earthenware, very often with a ceramic glaze , used for a wide variety of kitchen and dining functions, as well as objects such as chamberpots . In European contexts "redware" usually means an unglazed ("dry-bodied") stoneware , typically used for serving or drinking drinks. The term

952-542: The useful properties of clay. Some of the earliest pottery shards recovered are from central Honshu , Japan . They are associated with the Jōmon culture, and recovered deposits have been dated to around 14,000 BCE. Cooking pots, art objects, dishware, smoking pipes , and even musical instruments such as the ocarina can all be shaped from clay before being fired. Ancient peoples in Mesopotamia adopted clay tablets as

986-426: The water molecules are removed, and the plates hydrogen bond directly to each other, so that the dried clay is rigid but still fragile. If the clay is moistened again, it will once more become plastic. When the clay is fired to the earthenware stage, a dehydration reaction removes additional water from the clay, causing clay plates to irreversibly adhere to each other via stronger covalent bonding , which strengthens

1020-735: The world's population live or work in buildings made with clay, often baked into brick, as an essential part of its load-bearing structure. Clay is a very common substance. Shale , formed largely from clay, is the most common sedimentary rock. Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts , which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. Mixtures of sand , silt and less than 40% clay are called loam . Soils high in swelling clays ( expansive clay ), which are clay minerals that readily expand in volume when they absorb water, are

1054-493: 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 , 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

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1088-548: Was Böttger's first commercial ware and a significant stage in his development of porcelain in Europe, which he was soon making at the Meissen porcelain factory. Josiah Wedgwood later refined the type, and gave the decoration a fashionable turn towards Neoclassicism , with his "Rosso Antico" body. This was usually decorated with sprigged reliefs in black, creating pleasing contrasts like those in his earlier Jasperware . In American contexts "redware" usually means earthenware with

1122-461: Was used as a mortar in brick chimneys and stone walls where protected from water. Clay, relatively impermeable to water, is also used where natural seals are needed, such as in pond linings, the cores of dams , or as a barrier in landfills against toxic seepage (lining the landfill, preferably in combination with geotextiles ). Studies in the early 21st century have investigated clay's absorption capacities in various applications, such as

1156-524: Was useful. The name distinguishes the type from various other earthenwares with white, grey or yellow colours to the fired body, depending on the particular clay used. Some redware was imported from England. Later, American stoneware in particular, and various types of modern wares, including porcelain, took over for many types of objects. Major museum collections concentrate on the larger dishes, platters and jugs that are glazed, often in yellowish tones, and painted with bold folk art designs, even well into

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