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vendredi 23 avril 2010

Materials and Techniques Used In Pottery

Pottery is the oldest art of making clay utensils. It is basically clay (cement-like earth) which is modeled, dried and then fired into a vessel. Pottery may then be decorated with paint and glaze applied to it. There are certain materials used in making pottery. Clay is one of the most important materials used in making pottery and the clay used must be soft and malleable. Again clay is formed when rock decomposes into flat plates and water is trapped between these microscopic plates. Clay consists of 40% aluminum oxide, 14% water and 46% silicon oxide.

There are different types of clay and they can be grouped as primary clay and secondary clay. Primary clay is not mixed with other forms of sediment and it is not transported by water or glacier. Potter's clay is the most commonly used clay in creation of potteries. The secondary clay is mixed up with sediments and is lighter and finer than the previous one. Clay is sometimes given additives.

In the early stages of history, the main machine in making pottery was a potter's wheel. A potter's wheel was a wheel with a connecting wire which was tied to a pedal. The wheel spun as soon as the pedal was pushed and the potter shaped the pot with his hand when the clay was put in the center of the wheel. Clay was the main ingredient. It was made from mud or other kinds of dirt. The design was made using rocks, knives and twigs. Then the clay is placed in a kiln which is a type of oven used for heating the clay until it becomes solid. Glaze and/or paint adds a finishing touch to the pot.

However it must always be kept in mind that pottery is rarely made from raw clay. Clay is almost always mixed with other materials.

A variety of materials are used today in making pottery .The two most widely used materials in pottery are-

1. Ceramics

2. Porcelain.

Porcelain clay is made from white stone by crushing it and it is purified with water by mixing it until it becomes smooth and soft. This porcelain clay is also known as china clay or terracotta. There are different natural raw materials used in making traditional ceramics. The chemical used in the composition should be carefully measured so that no defects occur. The main motive of the chemical is to remove impurities or contamination. There are basically six types of ceramic raw materials - silica sand, clay, feldspar, calcium and magnesium carbonates, sodium and calcium borates and zirconium silicate. In a sample of ceramics the chemical cauterization is done by X-ray fluorescence, potentiometer, coulometer and atomic absorption spectrometry. There are again different ceramics with their own unique compositions used for making electrical goods as well.

These are some of the materials used in making pottery and ceramics. Today lots of research is being carried out for development in the field of pottery making and ceramics. This research aims at making better quality pottery by including different chemical substances and other enhancements.

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