The loose juxtaposition of clay particles is regarded as cause of thixotrophy by which we mean the spontaneous liquefaction of a semi stiff clay body on shaking and its re-consolidation on restoring the condition of rest. It is more in plastic bodies where alkalies have been used in their preparation. Water bound by the sodium clay is released temporarily under the influence of mechanical treatment in the shaping machine.
Too much water in throwing clay can also result in undesirable thixotropy. Thixotropy increases with reduction in particle size. In casting slip and glaze certain amount of thixotropy is desired. This facilitates the preparation of slip and prevents the glaze from running off the article during dipping.
To be contd…….
