What is "fritware"

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

It seems to have been first manufactured in Iraq in the 9th century. Egypt was the main center of manufacture between the 10th and the 12th century, but it then spread throughout the Middle-East until modern times.

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