Ceramics - How it's made | Ceramic Tiles

 

FILTER-PRESSING AND GRINDING 

The body mixture is not yet ready for tile-making, however: it must first be converted into powdered form. To this end it is pumped under pressure into a filter press consisting of a series of large envelopes of fine canvas held between concave-faced iron plates, with the result that the water trickles away through the canvas, leaving the solid particles behind in the form of large flat cakes of the plastic compound known as potter's clay. As the press is emptied, these cakes, each weighing about a hundredweight, fall into special iron trollies shaped like giant toast-racks on wheels, on which they are conveyed into the drying kilns, there to be freed from all traces of moisture. From these kilns the cakes emerge, hard as boards, to be broken up, slightly moistened, and finally ground in pans or mills to the fine powder known technically as "dust," which is automatically conveyed to the department or "shop" in which it will be converted into tiles. 

A filter press. Taking out the clay cakes

The critical reader may wonder why we first dry and then re-moisten the clay cakes. The reason is that only in this way can we be sure that the dust made from them will contain the right proportion of moisture – just enough to make it bind together properly under pressure and no more. Even a small error in the moisture content of the dust may seriously effect the ultimate product; and we may remark that the same is true of small errors in almost any of the multiplicity of small processes involved in tile manufacture. Only by the most careful attention to every detail can consistently good tiles be made. 

 

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