What is Egyptian faience?
Egyptian faience is the oldest known type of glazed ceramic. It was first developed more than 5,000 years ago in Egypt, Mesopotamia and elsewhere in the ancient world. It is composed mainly of silica (sand or crushed quartz), sodium and calcium. It is a self-glazing ceramic: sodium in the wet paste comes to the surface as it dries and forms a glaze when it is fired in the kiln. This is called efflorescence glazing. Metals in the paste color the glaze. Two common colorants are copper (turquoise) and cobalt (blue). Faience can also be created by placing small items such as beads in a container full of glazing powder (cementation glazing) or by painting on a glaze (application glazing). More than one glazing method may be used on a single piece. I make my own faience bodies and glazes, and I fire my faience pieces one or more times, usually using the efflorescence and application glazing techniques.
The word faience comes from the Italian town of Faenza which is famous for its pottery. This pottery is a red earthenware covered in a white glaze and decorated with colorful designs. (Majolica, Maiolica and Delftware are similar to the pottery of Faenza.) When Europeans came to Egypt in the 19th century, they apparently thought the brightly colored scarabs and other small faience items looked like the pottery of Faenza and they called these items faience. (It is also true that the term faience was sometimes used as a generic word for any type of glazed pottery.) In fact, Egyptian faience is very different from earthenware pottery. For this reason, some potters prefer to call it Egyptian paste. Archaeologists and other related professionals refer to this material as Egyptian faience or ancient faience or even just faience.
Here is a small faience pot that has dried in the air but has not yet been fired in the kiln (on the edge of the pot at the bottom of the photo there is a fuzzy white layer visible; this is the effloresced sodium that will become a layer of glaze when the pot is fired):
Here are some faience pendants that have been fired once (the turquoise glaze is a result of efflorescence):
And here's a small faience pot after it has been fired a second time with two layers of applied glaze on top of the effloresced glaze (the applied glazes are colored by cobalt and copper):
Archaeological research and replication experiments have shown that there were many recipes for Egyptian faience. These recipes varied by location and also over time. Here are some examples of different Egyptian faience recipes (these have all been fired just once and are glazed with the self-glazing efflorescence technique; the turquoise color is created by copper in the paste):
The online UCLA Encylopedia of Egyptology has an excellent article on ancient Egyptian faience by Paul T. Nicholson. For more suggested references, see my bibliography page.