Some Characteristics of Fireclay with Reference to Manufacturing Difficulties

JSGT_1935_V19_T139_T142

The characteristics considered are iron content, plasticity, shrinkage, and porosity. Two samples of fireclay were treated by an e1ectromagnetic method which removed accidental iron but did not lower the total iron content of the raw clay by more than 0·15%. Blunging the lump clay and then sieving without grinding did not affect any separation of iron which was evenly distributed throughout residue and fines. Plasticity cannot be given to a non-plastic clay by weathering; it is an inherent property of the raw clay and is often in inverse ratio to the depth of the seam below the surface. Shrinkage and porosity are closely related properties. Clay seams having irregular shrinkages can only be utilised in small quantities admixed with other clays, or as a grog material.

C.A.G. Thomas & J. R. Adderley