Bricks manufacturing: Preparation of clay

 The clay for bricks is prepared in the following order:

(1)Unsoiling: The top layer of soil, about 200mm in depth, is taken out and thrown away. The clay in top soil is full of impurities and hence it is to be rejected for the purpose of preparing bricks.

(2)Digging: The clay is then dug out from the ground. It is spread on the levelled ground, just a little deeper than the general level of ground. The height of heaps of clay is about 600mm to 1200mm.

(3)Cleaning: The clay, as obtained in the process of digging, should be cleaned of stones, pebbles, vegetable matter, etc. If there particles are in excess, the clay is to be washed and screened. The lumps of clay should be converted into powder form in the earth crushing roller.

(4) Weathering: The clay is then exposed to atmosphere for softening and mellowing. The period of exposure varies from few weeks to full season. For a large project, the clay is dug out just before the monsoon and it is allowed to weather throughout the monsoon.

(5)Blending: The clay is made loose and any ingredient to be added to it, is spread out at its top. The blending indicates intimate or harmonious mixing. It is carried out by taking small portion of clay every time and by turning it up and down in vertical direction. The blending makes clay fit for the next stage of tempering.

(6)Tempering: In the process of tempering, the clay is brought to a proper degree of hardness and it is made fit for the next operation of moulding. The water in required quantity is added to clay and the whole mass is kneaded or pressed under the feet of men or cattle. The tempering should be done exhaustively to obtain homogeneous mass of clay of uniform character.