EFFECT OF FRIT CATION RELEASE ON RHEOLOGICAL BEHAVIOR OF GLAZE SUSPENSIONS

The rheological conditions (yield stress, degree of deflocculation, vi scosity, etc.) of glaze suspensions used on an industrial scale in sin gle fire ceramic tile manufacture have often been observed to change g radually as such suspensions age. It is shown that ceramic frits do no t remain inert in glaze suspensions. Rather, these frits exhibit a cer tain solubility in water, as a result of which they can contribute cat ions to the glaze suspension, which can cause the viscosity of the sus pension to vary as it ages. A study was undertaken of how different ca tions (sodium, potassium, calcium, magnesium, zinc, barium, and boron) affect the viscosity imparted by the various glaze constituents (kaol in, sodium carboxymethylcellulose, and frit) to the suspension. The fi ndings showed that the interaction arising between the cations in the suspension and sodium carboxylmethylcellulose may cause viscosity to d rop. It was also established which cations had a more deleterious effe ct on glaze suspension viscosity. (C) 1996 The Institute of Materials.