Influence of nepheline syenite and milling time on the rheological properties of a porcelain stoneware tile slip

The rheological properties of porcelain stoneware tile slips were investigated using a rotational rheometer. The first step in the study was to evaluate the rheological behaviour of a reference slip at different particle size distributions to determine the optimum conditions at which to carry out the investigation of the influence of nepheline syenite in the mix. In the second step part of the K-feldspar in the reference mix was replaced with nepheline syenite such that the mix composition contained 10 % nepheline syenite. The flow curve, yield stress and thixotropy of the slips were evaluated at different milling times in order to study the effect of particle size on the rheological behaviour. The milling times for the reference mix and for the mix with nepheline syenite which resulted in the best rheological parameters were found.