Once a clay shape has been made and left to dry and harden, it is fired in a kiln, after which it's nature changes, going from clay to ceramics. Once this process has occurred, the clay is no longer workable, but has become durable and impervious to liquids. The word 'ceramics' has its roots in the Greek word keramos, meaning’ potters earth’. Vessels and receptacles such as plates, bowls, jugs and goblets are collectively known as pottery.
Ceramics and pottery were first made about 12 000 years ago. It is thought that foodstuff such as grain was kept in baskets, which were made of reeds woven together, and then lined with clay. It is impossible to say what first made man aware of the properties of clay, but a likely solution would be that one of the baskets fell into the fire and after the reeds had burned away the clay shell was left, effectively creating the first pot.
Earthenware
There are three basic types of pottery, earthenware, stoneware and porcelain. Earthenware fires the lowest of the clays, usually in the range of between 900° and 1100°. Terra cotta is an example of earthenware clay, and is quite porous. Because of this, most earthenware clay is not suitable to hold liquid, unless glazed. Specialist clays such as raku are also earthenware and fall in the lower temperature firing range.
Earthenware clay is never pure, containing detritus that it has collected on its journey, such as leaves and other vegetation, and minerals such as iron. These impurities are the reason why the firing temperature is lower than that of other clays. This clay travels through river beds and along streams over a long period of time, which causes the colour to darken, and also makes it more plastic and workable.
Stoneware
Stoneware is high-fired, non-porous clay. The firing temperature ranges from 1100° to 1200° for the lower temperature range, to between 1200° – 1300° for the higher temperature range. Stoneware clay particles are finer than that of earthenware clays, and when fired correctly, are dense and hard, with the same qualities as stone, hence the name ‘stoneware’.
They are non-porous, durable and strong, and are often used today to make casseroles or similar oven ware dishes. The colour of stoneware ranges from light grey when wet, to grey, buff and beige coloured, and can even be as dark as chocolate brown when fired. The finished colour is often representative of the type of firing which the clay has undergone.
Porcelain
This is the purest form of clay, and is made of kaolin, which is derived from the Chinese word for ‘high hill’, which is where clay was first found in China. Because this clay has not travelled, but has remained completely uncontaminated, it’s colour ranges from light grey when mixed with ball clay, to pure white. Ball clay is often added to improve plasticity, as porcelain is difficult to work with.
It is thought that the first porcelain wares were manufactured during the T’ang Dynasty in China (618 – 906), having evolved from high-fired, glazed ceramic ware during the Han Dynasty. Porcelain is translucent, and the word derives from the Italian porcellana, meaning cowrie shell, due to its resemblance to the surface of this fragile and lustrous sea shell.
Ceramics has a rich and diverse history and background, irrespective of the culture or the type of clay they used. Ancient pieces of pottery are treasured today, as they offer an insight into an ancient world and the cultures and civilizations from the past. Traditions and beliefs are often depicted on a specific society’s pottery, making it easier to decipher their way of life. Because ceramics has an infinite lifetime, the broken shards of pots and vessels which have been buried with the trappings of a society can paint a picture of that time.
Resources:
- Savage, G Pottery Through the Ages Pelican Books (1959)
- Scholes, S Book of Knowledge Grolier Incorporated (1979)
- Cooper, E A History of World Pottery Batsford LTD (1988)
Mellissa Bushby - Mellissa Bushby is an author, illustrator and ceramicist. She studied Fine Art for four years, and her newest book release is January ...
