Fritware

Last updated January 03, 2024

Fritware, also known as stone-paste, is a type of pottery in which frit (ground glass) is added to clay to reduce its fusion temperature. The mixture may include quartz or other siliceous material. An organic compound such as gum or glue may be added for binding. The resulting mixture can be fired at a lower temperature than clay alone. A glaze is then applied on the surface.

Fritware was invented to give a strong white body, which, combined with tin-glazing of the surface, allowed it to approximate the result of Chinese porcelain. Porcelain was not manufactured in the Islamic world until modern times, and most fine Islamic pottery was made of fritware. Frit was also a significant component in some early European porcelains.

A small manufacturing cluster of fritware exists around Jaipur, Rajasthan in India, where it is known as 'Blue Pottery' due its most popular glaze. The Blue Pottery of Jaipur technique may have arrived in India with the Mughals,^[1] with production in Jaipur dating to at least as early as the 17th century.^[2]^[3]

Composition and techniques

Fritware was invented in the Medieval Islamic world to give a strong white body, which, combined with tin-glazing of the surface, allowed it to approximate the white colour, translucency, and thin walls of Chinese porcelain. True porcelain was not manufactured in the Islamic world until modern times, and most fine Islamic pottery was made of fritware. Frit was also a significant component in some early European porcelains.

Although its production centres may have shifted with time and imperial power, fritware remained in continued use throughout the Islamic world with little significant innovation.^[4] The technique was used to create many other significant artistic traditions such as lustreware, Raqqa ware, and Iznik pottery.^[5]^[6]

Raw materials in one contemporary recipe used in Jaipur are quartz powder, glass power, Fuller's earth, borax and Tragacanth gum.^[7]^[8] Raw materials for a glaze are reported to be glass powder, lead oxide, borax, potassium nitrate, zinc oxide and boric acid. The blue decoration is cobalt oxide.^[9]

History

Frit is crushed glass that is used in ceramics. The pottery produced from the manufacture of frit is often called 'fritware' but has also been referred to as "stonepaste" and "faience" among other names.^[10] Fritware was innovative because the glaze and the body of the ceramic piece were made of nearly the same materials allowing them to fuse better and less likely to flake and could also be fired at a lower temperature.^[11] Such traditions of low firing temperatures were not uncommon throughout the Middle East and Central Asia, having examples of the technique dating to the 11th century BC when it may have been developed.^[12]

The manufacture of proto-fritware began in Iraq in the 9th century AD under the Abbasid Caliphate,^[13] and with the establishment of Samarra as its capital in 836 there is extensive evidence of ceramics in the court of the Abbasids both in Samarra and Baghdad.^[14] A ninth-century corpus of 'proto-stonepaste' from Baghdad has "relict glass fragments" in its fabric.^[10] The glass is alkali-lime-lead-silica and, when the paste was fired or cooled, wollastonite and diopside crystals formed within the glass fragments. The lack of "inclusions of crushed pottery" suggests these fragments did not come from a glaze.^[10] The reason for their addition would have been to release alkali into the matrix on firing, which would "accelerate vitrification at a relatively low firing temperature, and thus increase the hardness and density of the [ceramic] body."^[10]

Following the fall of the Abbasid Caliphate, the main centres of manufacture moved to Egypt where true fritware was invented between the 10th and the 12th centuries under the Fatimids, but the technique then spread throughout the Middle East.^[13]

There are many variations on designs, colour, and composition, the last often attributed to the differences in mineral compositions of soil and rock used in the production of fritware.^[5] The bodies of the fritware ceramics were always made quite thin to imitate their porcelain counterparts in China, a practice not common before the discovery of the frit technique which produced stronger ceramics.^[11] In the 13th century the town of Kashan in Iran was an important centre for the production of fritware.^[15] Abū'l-Qāsim, who came from a family of tilemakers in the city, wrote a treatise in 1301 on precious stones that included a chapter on the manufacture of fritware.^[16] His recipe specified a fritware body containing a mixture of 10 parts silica to 1 part glass frit and 1 part clay. The frit was prepared by mixing powdered quartz with soda which acted as a flux. The mixture was then heated in a kiln.^[16]^[10] The internal circulation of pottery within the Islamic world from its earliest days was quite common, with the movement of ideas regarding pottery without their physical presence in certain areas being readily apparent.^[14] The movement of fritware into China - whose monopoly on porcelain production had prompted the Islamic world to produce fritware to begin with - impacted Chinese porcelain decoration, deriving the signature cobalt blue colour from Islamic traditions of fritware decoration.^[17] The transfer of this artistic idea was likely a consequence of the enhanced connection and trade relations between the Middle and Near East and Far East Asia under the Mongols beginning in the 13th century.^[17] The Middle and Near East had an initial monopoly on the cobalt colour due to its own richness in cobalt ore, which was especially abundant in Qamsar and Anarak in Persia.^[18]

Iznik pottery was produced in Ottoman Turkey beginning in the last quarter of 15th century AD.^[6] It consists of a body, slip, and glaze, where the body and glaze are 'quartz-frit'.^[6] The 'frits' in both cases "are unusual in that they contain lead oxide as well as soda"; the lead oxide would help reduce the thermal expansion coefficient of the ceramic.^[6] Microscopic analysis reveals that the material that has been labeled 'frit' is 'interstitial glass' which serves to connect the quartz particles.^[6] The glass was added as frit and the interstitial glass formed on firing.

In 2011, 29 potteries, employing a total of 300 persons, making fritware were identified in Jaipur.^[19]

Applications

Fritware served a wide variety of purposes in the medieval Islamic world. As a porcelain substitute the fritware technique was used to craft bowls, vases, and pots as both symbols of luxury as well as to more practical ends.^[5] It was similarly used by medieval tilemakers to craft strong tiles with a colourless body that provide a suitable base for underglaze and decoration^[14] Fritware was also known to be used to craft objects beyond simply pottery and tiling. It was also found to be used in the twelfth century to make objects like chess sets.^[20] There is also a tradition of using fritware to create intricate figurines, with surviving examples from the Seljuk Empire.^[21]

It was also the use ceramic body for Islamic lustreware, a technique that puts a lustred ceramic glaze onto pottery.^[5]

Related Research Articles

Pottery is the process and the products of forming vessels and other objects with clay and other raw materials, which are fired at high temperatures to give them a hard and durable form. The place where such wares are made by a potter is also called a pottery. The definition of pottery, used by the ASTM International, is "all fired ceramic wares that contain clay when formed, except technical, structural, and refractory products". End applications include tableware, decorative ware, sanitaryware, and in technology and industry such as electrical insulators and laboratory ware. In art history and archaeology, especially of ancient and prehistoric periods, pottery often means vessels only, and sculpted figurines of the same material are called terracottas.

Lead glass, commonly called crystal, is a variety of glass in which lead replaces the calcium content of a typical potash glass. Lead glass contains typically 18–40% lead(II) oxide (PbO), while modern lead crystal, historically also known as flint glass due to the original silica source, contains a minimum of 24% PbO. Lead glass is often desirable for a variety of uses due to its clarity. In marketing terms it is often called crystal glass.

"Blue and white pottery" covers a wide range of white pottery and porcelain decorated under the glaze with a blue pigment, generally cobalt oxide. The decoration is commonly applied by hand, originally by brush painting, but nowadays by stencilling or by transfer-printing, though other methods of application have also been used. The cobalt pigment is one of the very few that can withstand the highest firing temperatures that are required, in particular for porcelain, which partly accounts for its long-lasting popularity. Historically, many other colours required overglaze decoration and then a second firing at a lower temperature to fix that.

Islamic pottery occupied a geographical position between Chinese ceramics, and the pottery of the Byzantine Empire and Europe. For most of the period, it made great aesthetic achievements and influence as well, influencing Byzantium and Europe. The use of drinking and eating vessels in gold and silver, the ideal in ancient Rome and Persia as well as medieval Christian societies, is prohibited by the Hadiths, with the result that pottery and glass were used for tableware by Muslim elites, as pottery also was in China but was much rarer in Europe and Byzantium. In the same way, Islamic restrictions greatly discouraged figurative wall painting, encouraging the architectural use of schemes of decorative and often geometrically patterned titles, which are the most distinctive and original specialty of Islamic ceramics.

Underglaze is a method of decorating pottery in which painted decoration is applied to the surface before it is covered with a transparent ceramic glaze and fired in a kiln. Because the glaze subsequently covers it, such decoration is completely durable, and it also allows the production of pottery with a surface that has a uniform sheen. Underglaze decoration uses pigments derived from oxides which fuse with the glaze when the piece is fired in a kiln. It is also a cheaper method, as only a single firing is needed, whereas overglaze decoration requires a second firing at a lower temperature.

<span class="mw-page-title-main">Tin-glazing</span>

Tin-glazing is the process of giving tin-glazed pottery items a ceramic glaze that is white, glossy and opaque, which is normally applied to red or buff earthenware. Tin-glaze is plain lead glaze with a small amount of tin oxide added. The opacity and whiteness of tin glaze encourage its frequent decoration. Historically this has mostly been done before the single firing, when the colours blend into the glaze, but since the 17th century also using overglaze enamels, with a light second firing, allowing a wider range of colours. Majolica, maiolica, delftware and faience are among the terms used for common types of tin-glazed pottery.

Egyptian faience is a sintered-quartz ceramic material from Ancient Egypt. The sintering process "covered [the material] with a true vitreous coating" as the quartz underwent vitrification, creating a bright lustre of various colours "usually in a transparent blue or green isotropic glass". Its name in the Ancient Egyptian language was tjehenet, and modern archeological terms for it include sintered quartz, glazed frit, and glazed composition. Tjehenet is distinct from the crystalline pigment Egyptian blue, for which it has sometimes incorrectly been used as a synonym.

Blue Pottery is widely recognized as a traditional craft of Jaipur of Central Asian origin. The name 'blue pottery' comes from the eye-catching cobalt blue dye used to color the pottery. It is one of many Eurasian types of blue and white pottery, and related in the shapes and decoration to Islamic pottery and, more distantly, Chinese pottery.

Ceramic glaze, or simply glaze, is a glassy coating on ceramics. It is used for decoration, to ensure the item is impermeable to liquids and to minimise the adherence of pollutants.

Iznik pottery, or Iznik ware, named after the town of İznik in Anatolia where it was made, is a decorated ceramic that was produced from the last quarter of the 15th century until the end of the 17th century. Turkish stylization is a reflection of Chinese Porcelain.

A frit is a ceramic composition that has been fused, quenched, and granulated. Frits form an important part of the batches used in compounding enamels and ceramic glazes; the purpose of this pre-fusion is to render any soluble and/or toxic components insoluble by causing them to combine with silica and other added oxides. However, not all glass that is fused and quenched in water is frit, as this method of cooling down very hot glass is also widely used in glass manufacture.

This is a list of pottery and ceramic terms.

Tin-glazed pottery is earthenware covered in lead glaze with added tin oxide which is white, shiny and opaque ; usually this provides a background for brightly painted decoration. It has been important in Islamic and European pottery, but very little used in East Asia. The pottery body is usually made of red or buff-colored earthenware and the white glaze imitated Chinese porcelain. The decoration on tin-glazed pottery is usually applied to the unfired glaze surface by brush with metallic oxides, commonly cobalt oxide, copper oxide, iron oxide, manganese dioxide and antimony oxide. The makers of Italian tin-glazed pottery from the late Renaissance blended oxides to produce detailed and realistic polychrome paintings.

Chinese influences on Islamic pottery cover a period starting from at least the 8th century CE to the 19th century. This influence of Chinese ceramics has to be viewed in the broader context of the considerable importance of Chinese culture on Islamic arts in general.

Persian pottery or Iranian pottery is the pottery made by the artists of Persia (Iran) and its history goes back to early Neolithic Age. Agriculture gave rise to the baking of clay, and the making of utensils by the people of Iran. Through the centuries, Persian potters have responded to the demands and changes brought by political turmoil by adopting and refining newly introduced forms and blending them into their own culture. This innovative attitude has survived through time and influenced many other cultures around the world.

Lead-glazed earthenware is one of the traditional types of earthenware with a ceramic glaze, which coats the ceramic bisque body and renders it impervious to liquids, as terracotta itself is not. Plain lead glaze is shiny and transparent after firing. Coloured lead glazes are shiny and either translucent or opaque after firing. Three other traditional techniques are tin-glazed, which coats the ware with an opaque white glaze suited for overglaze brush-painted colored enamel designs; salt glaze pottery, also often stoneware; and the feldspathic glazes of Asian porcelain. Modern materials technology has invented new glazes that do not fall into these traditional categories.

Cuerda seca is a technique used when applying coloured glazes to ceramic surfaces.

Ceramic art is art made from ceramic materials, including clay. It may take varied forms, including artistic pottery, including tableware, tiles, figurines and other sculpture. As one of the plastic arts, ceramic art is a visual art. While some ceramics are considered fine art, such as pottery or sculpture, most are considered to be decorative, industrial or applied art objects. Ceramic art can be created by one person or by a group, in a pottery or a ceramic factory with a group designing and manufacturing the artware.

Kubachi ware is a style of Persian pottery. Though it takes its name from the town of Kubachi in Dagestan, modern-day Russia, scholars believe that Kubachi ware pieces were created during the Safavid Period in the northwestern part of what is now Iran. Nishapur, Tabriz, Mashhad, and Isfahan have all been put forth as possible places of origin for Kubachi ware.

Lajvardina-type ceramics were developed in the 13th century following the Mongol invasion of Persia. It was produced throughout the Ilkhanate reign. It is characterized by its deep blue color and often features geometric patterns or foliage inlaid with gold leaf. The style was created using overglaze enamel. An initial layer of dark blue glaze, produced from cobalt, was applied, followed by another layer, often gold, on which the details were painted. It was primarily produced in Kashan, a center for ceramic production and lusterware in the 12th and early 13th centuries. The style was continuously used for tiles and ornamental objects from the 1260s C.E. until the mid-14th century, when production dropped significantly, coinciding with the fall of the Ilkhanate in 1335.

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