Since the beginnings of time, and until the 12th century CE , European potters generally worked with common clays, readily available throughout the continent. These earths were full of impurities, mainly iron, an element that imparts a reddish colour to most ceramics after firing. Earthenware was the most basic and universal ceramic product, and is still widely used today to make bricks, tiles and flowerpots.
In Roman times, new techniques began arriving from the Middle East, and potters started covering earthenware with a transparent, lead-based glaze. This innovation made the earthenware watertight and more hygienic to use, but the clear glaze could not hide the strong coloration of the underlying clay. The final product was still a relatively unrefined object and not easy to decorate.
The event that was to revolutionize the history of ceramics was the emergence in China, probably as early as the 7th century CE, of porcelain. This new ceramic was so extraordinary, with its immaculate whiteness, its strength, its resonance and its translucency, that it was to be a source of fascination for centuries. Unlike earthenware, porcelain is the result of already highly sophisticated technology. Firstly, it is a composite product: a clever mix of quartz, feldspar and in particular kaolin (also known as china clay), a naturally pure clay found only in certain specific deposits. What’s more, porcelain has to be fired at very high temperatures - between 1300 and 1400 degrees centigrade - temperatures that only the Chinese were able to master at the time.
In the 8th and 9th centuries CE, caravans that travelled the Silk Road brought the first samples of Chinese porcelain to the Middle East. They aroused envy and admiration, especially in Mesopotamia, where the Caliph of Baghdad, Harun al-Rashid, incited local makers to imitate these fabulous exotic ceramics. The Mesopotamian potters of course knew nothing of the secrets of porcelain manufacture, but they met the challenge to some extent in the 9th century by the invention of a new ceramic process, better known in Europe as faience. At first sight, faience has a surface almost as white and smooth as porcelain; a surface that soon lent itself to all kinds of decorative fantasies. Yet from the outset it was only a substitute for porcelain: nothing more than earthenware coated with a lead glaze rendered white and opaque by the addition of tin oxide. This enhanced glaze is also called a tin glaze. In all other respects, faience lacks the strength, the finesse and especially the translucency of porcelain. It nevertheless had a brilliant future ahead of it: for four centuries, until Europe was able to produce its own porcelain, faience reigned supreme as the most sophisticated and artistically the most ambitious ceramic product throughout the western hemisphere.