Jars, vases, teacups and saucers, plates, bowls, mugs and the like all fall under the heading of pottery, or ceramic ware, as do bricks, tiles and certain engine parts. The soft, malleable clay is shaped and moulded, allowed to dry to a ‘leather-hard’ stage, and is then fired in a kiln, wether primitive or otherwise, to the required temperature, depending on the type of clay which has been used.
While different types of clay require different firing times, there are also certain techniques more suited to specific kinds of clay than others. A raku firing, for example, can be undertaken in an electric kiln, but a gas kiln is more commonly used. There are numerous reasons for this, personal preference in kiln usage being one of them, as many people prefer not to expose their expensive electric kiln to the extremes of rapid temperature change which is the trademark of Raku. Also, gas kilns typically reach temperature much faster than electric kilns, reducing firing time.
Terra-Cotta and Earthenware Clay
The clay most commonly used for Raku, as well as pit-fired wares, is terra-cotta, or a low-fired earthenware body, which is bisque fired to around 1000°. This method of firing puts extreme stress on the ware, thus a strong clay body is used. Terra-cotta is one of the most plastic, pliable types of clay, due to its exposure to earthy elements. Earthenware clays have travelled down mountainsides and riverbeds over the centuries, collecting debris and organic matter. Pure clay, such as porcelain, is found at a much higher altitude than terra-cotta, and has not been exposed to the acids or vegetation that terra-cotta absorbs on its journey. Porcelain also has a much higher firing range, typically around 1200°.
Ceramics is one of the oldest materials ever used by man. Clay is found almost everywhere, and it is a simple procedure to dig moist clay from a river bed, for the purpose of shaping it into a figurine, bowl or carving. There is a simple progression from the point which sees the soft clay becoming hard and brittle when dry; towards realising that the clay hardens when exposed to a heat source, becoming stronger when left in the sun.
Fire as a Ceramic Tool
Because the higher the heat source the more durable and resilient the clay will become, fire became the chief means of strengthening clay. Pottery pieces have been found that date back to pre-recorded history and clay, once fired, cannot rot, rust or otherwise erode in any way. It is durable and eternal, as well as having the ability to hold liquids such as oil, wine or water, leading to the primitive production of receptacles such as jugs, bowls to hold food, and storage jars for the purpose of grain.
Due to its permanence, ceramics is one of the chief means of discovery regarding ancient civilizations and their belief systems. Each culture has distinctive decorative features or styles which they used to decorate their pottery, archaeologists can often tell the age and the specific culture that produced a pot simply from looking at its shape or decoration.
Understanding the Past
Another valuable resource when deciphering the past are the written clay tablets which have been discovered over the centuries, such as the Rosetta stone. Most of the writing found on the tablets pertains to business records, or political listings. These lists were invaluable, the diverse information they contained regarding crops, borders, enemies and allies, legal records and so on being essential to the smooth running of a farm, family or kingdom. Their importance meant that they had to have a long lifespan, and be resilient and durable.
Apart from historical records on tablets, the pitchers and urns used for grain, oil and wine storage also had to be hard-wearing and long-lasting, as they were often used to store items through times of drought. Items of this nature were fired in primitive pits, a procedure still used today both for its beautiful and unpredictable decorative features, but also, in certain countries, as the dominant firing method, for example in many in parts of Africa. Wares are stacked in a mound, or placed in a hole dug into the ground, covered with combustible materials such as twigs, grass, leaves and straw, and left to burn slowly.
Resources:
- Scholes, S The Book of Knowledge Grolier (1979)
- Freestone, I Pottery in the Making British Museum Press (1997)
- Cooper, E 10000 Years of Pottery British Museum Press (1972)
Mellissa Bushby - Mellissa Bushby is an author, illustrator and ceramicist. She studied Fine Art for four years, and her newest book release is January ...
