The type, nature and function of clay and other materials to create ceramic objects can be divided into two groups, namely:
Kaolin is also called china clay, clay types including primary (residue) that serves as a major component in making a mixture of porcelain, and is used in ceramic stoneware and white Earthenware. Kaolin and enhancer-binding function for ceramic body strength at high temperatures, porcelain, refractory goods (refractory), is also used as a reinforcement material in the manufacture of glaze.
The properties of kaolin (china clay):
- coarse grained
- not plastic
- relatively pure
- white color
- high melting point is 1800 0 C.
2. Ball clay
Ball clay, including the type of secondary clay (sediment / sludge) that has particles so fine that the level of plasticity and high dry strength, contains a lot of organic matter. Ball clay is generally used as an ingredient to make the white ceramic (ceramic smooth and in the email, also to make clay slip poured more liquid. In a plastic mass can increase their power and strong dry.
The properties of ball clay:
- fine-grained
- very high plasticity
- depreciation of 20%
- keing high strength
- melting point temperature of 1300 0 C
- gray
3. Stoneware
Stoneware clay is a material that is plastic refraktoris, including the type of secondary clay (sediment) has a low shrinkage, fine-grained and is widely used to make the object binders and colorants. Stoneware will produce solid objects and water-resistant when burned at a temperature of 1250 0 C – 1300 0 C without deformation.
- fine-grained,
- plastic,
- low shrinkage,
- low porosity,
- soil temperature reaches melting point 1400 0 C,
- raw color gray, dirty yellow,
- refractory,
Earthenware including secondary soil (sediment), clay is easily found in various areas, plastic, fine-grained with a fairly high iron content. This clay has a considerable degree of plasticity, making it easy to set up, but also have a high degree of shrinkage as well.
Once burned in strength and very porous, absorption (the ability to absorb) more water and 3%, low fuel temperatures between 900 0 C-1060C, roasted red brown color and melting point of about 1100C-1200C. Red clay tiles are widely used in industry, brick and pottery rough and smooth. Natural color is not bright red, but red rust, because of its iron content reached 8%, when glazed color will be richer, especially with the use of lead glaze (poisonous).
Earthenware clay is widely used in the manufacture of ceramic objects Earthenware, pottery, brick, tile, and can be used as a colorant in glazes.
Earthenware properties:
- plastic,
- fine-grained
- iron content is high enough
- raw color red, brown, gray, black,
- Fuel temperature between 900 0 C 1060 0 C
5. Fire Clay
Fire Clay including secondary soil (sediment) is a type of clay that is resistant to heat and do not change shape, has a high melting point is 1600 ° C-1750 ° C. Most clay refractory light-colored (white) to dark gray to black head and is found in nature in the form of solid chunks, some of which yield high alumina and low levels of alkali.
Were classified as refractory clay is impervious clay burnt at high temperatures without changing the shape of, for example, kaolin and refractory minerals such as alumina and silica. Fireclay serves as a refractory material to make items such as fire bricks, furnace equipment, the ceramic body as a compound to increase the ability of shape-making stoneware and porcelain products.
The properties of fire clay:
- tend to be plastic,
- coarse grains,
- low absorption rate
- medium shrinkage
- resistant to high temperature (refractory)
- The properties of bentonite:
- highly plastic.
- fine-grained
- melting point of 1200 º C
Figure 6.18. Plastic ceramic materials.