Pottery is one of the oldest inventions of man with evidences dating as far back as 29,000 B.C.
Pottery is an art of making ceramic wares out of clay. All materials made from this process are classified as either Earthenware, Stoneware or Porcelains.
Contrary to the definition, although it is always involved and is the main component, clay is not the only material used. There are also other additives (such as salts) added to give the materials high and better quality.
There are also different type of clay used depending on the kind of product that is needed in terms of purity and plasticity. They majorly include:
- Primary clay or Kaolin
- Secondary clay or Clay ball
- Stoneware
- Red mud surface
- Bentonite
Production stages in Pottery
Materials made from clay undergo different stages that changes and modifies their physical properties. These stages include:
After moulding and shaping using appropriate clay and techniques, the resulting product is called a greenware. A Greenware is a shaped pottery that is about to be dried and is yet to be fired. Depending on the moisture content, it can be deformed if not handled properly.
Leather hard refers to a clay body that has dried partially. At this stage the clay object has about 15% moisture content. Trimming and attachment of handle (as in jars) often occurs at the leather-hard state.
At a moisture content of or near 0%, the clay body is referred to as Bone-dry. At this stage, the material is ready to be bisque fired.
The firing of a bone-dry clay body in the kiln for the first time is known as bisque-firing and the product is called a Bisque or Biscuit. This process changes the clay body in several ways. Some mineral components (such as iron oxide) are affected and can cause change in appearance in terms of colour and virification of the clay body.
Glaze can serve to colour, decorate or waterproof the item. Glazes are oxides that may be applied to the bisque form and the object can be decorated in several ways. After this the object is "glazed fired", which causes the glaze material to melt, then adhere to the object. Glaze firing will also harden the body more.
Glaze-fired clay body is the final stage of some pottery materials.
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Traditionally, hand moulding and the potter's wheel is generally and widely used by potters in making Pottery. However, advancement in tools and technologies gave way for easier methods such as, Injection moulding, Pressure casting and even 3D printing.
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