Clustering of zircon in raw glaze and its influence on optical properties of opaque glaze

Abstract The cluster of zircon (ZrSiO 4 ) is always observed on the surface of a zircon-containing raw glaze. This work studied the cluster's formation mechanism and its influence on optical properties of opaque glaze by comparing a zircon-containing raw glaze with a zirconium-based frit one. It was observed that the cluster of zircon occurs during the densification of the raw glaze. We found evidences that this phenomenon is caused by the releasing of gas when the glaze is vitrifying. The optical analysis revealed that the cluster of zircon has a significant effect on the scattering of light and also on the color of the studied glazes.