What are Ceramics & What is Clay?

What are Ceramics?

The word Ceramic is derived from the Greek “Keramikos”, which has its roots in the Sanskrit word “substance developed by fire”. Its Greek translation appears to vary from “burnt stuff” to “potters clay”. Ceramics are made from non-metallic minerals, usually oxides and silicates, that have been transformed in physical state by heat. Once heated or “fired” at a sufficient temperature and for a sufficient time, the basic ceramic becomes virtually indestructible; that is, the object is perhaps brittle and breaks, but the broken pieces or “shards/sherds” will last for thousands of years. This makes ceramics (commonly “pottery” in this context) hugely important as a record of man’s development through the ages.

Sherds of Egyptian Pottery, Badarian Period, 4,700 to
4,000 BC - UC 72966 - copyright of the Petrie Museum
of Egyptian Archaeology, UCL

The earliest production of ceramics by man, for ritual items and domestic pottery, used local clays as the source of the minerals and these were then fired in open fires at first, but later in kilns (special ovens). Scientific uses of ceramics came much later and are covered in subsequent sections. There are several main types of ceramics for domestic use; namely, earthenware or terracotta (varieties subsequently called majolica, delft or faience), stoneware and porcelain. Each is achieved at higher and more controlled firing temperatures and times, and consequently were discovered at later dates than the earliest earthenware pottery. Glass is not a true ceramic but is a “super-cooled liquid”. As the name implies, even though solid, it retains the characteristics of a liquid – in this case it is homogenous (amorphous) and has no crystal structure. However, glass is related to ceramics in a number of ways and so receives mention where relevant.