Ceramics - How it's made | Ceramic Tiles

 

FIRING THE GREEN WARE     - continued...

 

Biscuit kiln, Brownhills. Mr. Geoff Corn inspecting the output.

 

In the case of the tunnel kiln, some 120 saggars containing perhaps 100 square yards of tiles are placed on the platform of a heavy fireclay truck, which is then slowly hauled by an endless wire rope to the charging end of the kiln. Here it joins the long train of trucks already filling the kiln from end to end. Electric propelling gear urges it, with the fifty odd trucks ahead of it, slowly forward on its four days' 
firing journey, on which it will be followed by other trucks at intervals of two hours or so. As it moves forward through the 120 odd yards of the kiln's length at about four feet an hour, it encounters steadily rising temperatures, until, after some 48 hours, it enters the actual firing zone. Here it – or rather its load – passes through a long barrage of flames – clean, smokeless and intensely hot flames caused by the burning of "producer" gas, for the making of which we have one of the finest plants in the kingdom – which completely envelop the saggars, raising them and their contents to white heat. Leaving the firing zone a day later the truck and its load begin slowly to cool. Twenty-four hours more and, still cooling, they are out of the kiln and on the returnw ay. moving slowly towards the "emptying" benches. Arrived there the tiles are removed from the saggars and placed on inspection tables, while saggars and truck are moved forward to the "placers" a few yards further on, reloaded, and sent off on one more of their endless sequence of journeys. 

 

A 'bottle' oven interior. 'Setting in' prior to firing.

 

Floor tiles and mosaics will go through firing experiences essentially the same as, though differing widely in detail from, those just described. Ten or twelve hundred square yards of them, packed in two thousand or more saggars, will be carried into the gloomy vaulted interior of a great bottle-shaped oven, whose narrow entrance will then be solidly bricked up and whose fires lighted. For the next five days the temperature of the oven will rise steadily till it stands at about 1,250 degrees centigrade – slightly above the melting point of cast iron. The fires will then be allowed to die down, and two or three days later, when the heat has sufficiently diminished, the oven door will be broken through, and the saggars conveyed to the sorting warehouse to be relieved of their contents. 

'Drawing' a 'bottle' oven. A peep through the entrance.

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From: "A Century of Progress 1837-1937" a publication to commemorate The Centenary of Richards Tiles Ltd.