Fritware, also known as stone-paste, is a type of pottery in which ground glass (frit) is added to clay to reduce its fusion temperature. The mixture may include quartz or other siliceous material. An organic compound such as Natural gum or glue may be added for binding. The resulting mixture can be fired at a lower temperature than clay alone. A Ceramic 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.
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. The technique was used to create many other significant artistic traditions such as lustreware, Raqqa ware, and Iznik pottery.
Raw materials in one contemporary recipe used in Jaipur are quartz powder, glass power, fuller's earth, borax and tragacanth gum.'An Interactive Design Study of Jaipur Blue Pottery' Need Assessment Survey Report, MSME Design Clinic Scheme. 2011. Pgs. 9–11'Evolution of Blue Pottery Industry in Rajasthan' Bhardwaj A. International Journal of Research and Analytical Reviews. Vol. 5, Iss. 3 July–Sept. 2018 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.'Blue Pottery of Jaipur' Pande A. International Journal of Research - Granthaalayah. Vol.7. Iss.3. March 2019
The manufacture of proto-fritware began in Iraq in the 9th century AD under the Abbasid Caliphate, Archaeological chemistry by Zvi Goffer p.254 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. A ninth-century corpus of 'proto-stonepaste' from Baghdad has "relict glass fragments" in its fabric. 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. 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."
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.
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. 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. In the 13th century the town of Kashan in Iran was an important centre for the production of fritware.
Iznik pottery was produced in Ottoman Empire beginning in the last quarter of 15th century AD. It consists of a body, slip, and glaze, where the body and glaze are 'quartz-frit'. 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. Microscopic analysis reveals that the material that has been labeled 'frit' is 'interstitial glass' which serves to connect the quartz particles. 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.'An Interactive Design Study of Jaipur Blue Pottery' Need Assessment Survey Report, MSME Design Clinic Scheme. 2011. Pgs. 9-11
It was also used as the ceramic body for Islamic lustreware, a technique that puts a lustred ceramic glaze onto pottery.
Applications
Blue pottery
Further reading
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