The role of viscosity on microstructure development and stain resistance in porcelain stoneware tiles

Effect of composition on viscosity of porcelain stoneware tiles and role of the viscosity on microstructure development and stain resistance in porcelain stoneware tiles were investigated. The viscosity of the tiles was successfully measured by a thermomechanical analyzer. Na2O/K2O ratio was used as a parameter to change the viscosity. As the Na2O/K2O ratio increases, the viscosity decreases. This reduction in the viscosity results in improvement of microstructure (i.e., spherical pore morphology and reduced closed porosity) and usually increases the stain resistance significantly. However, too low viscosity may also cause deformation of the tile during production. Therefore, the viscosity of the tiles should be carefully controlled and it should lie between a lower limit (in this study this value is between 107.93 and ∼108.35 P) and an upper limit (in this study this value is 108.67 P) to achieve high stain resistant porcelain tiles with no deformation.