Melting behaviour of raw glazes

Melting behaviour of raw and inhomogeneous glazes influences the appearance and the properties of the final glaze surface. The melting behaviour was estimated from the sintering curves and characteristic samples measured with hot-stage microscopy. The glaze compositions were statistically chosen to cover the glaze-forming systems used in traditional ceramic industries. Altogether seventy-five compositions were mixed and ball-milled from seven different raw materials. The temperatures describing the sintering and melting of the glazes were mathematically modelled as functions of the raw material compositions. All the compositions were then also applied on raw floor tiles and fired in an industrial kiln for fast-firing (50 min) of dense floor tiles. The gloss of the fired glazes was mathematically modelled as a function of both the raw material and the oxide compositions. The resistance to abrasion and the crystalline phases of the fired surfaces were also determined.