The tiles are burnt in a kiln which could accommodate 30,000–40,000 tiles. Such kilns are partly underground and are usually provided with a roof to protect the kiln from rain.
A layer of bricks is laid over the long narrow flues, and the flues are fed with wood. The bricks are so placed such that open spaces are left in between them so that flues can move.
Above the layer of bricks, the dried tiles are placed on edge layer by layer, until the kiln is fully filled with raw tiles. The doorways are closed.
The kiln is then fired initially with 800ºC, slaked for six hours and then increased to 1,300ºC for about 3 hours (Fig. 4.2). Once again it is slacked for 6 hours and then once more heated and kept steady for about 3–4 hours. Finally, the flues are filled with fuel and the doorways are closed by brickwork in mud. The kiln is cooled gradually over 72 hours. Then the tiles are removed.
Figure 4.2 Circular kiln for burning tiles
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