Influence of viscosity and composition of alkali borosilicate lead-free frit on its reaction with hematite, and the color control of red overglaze enamels

Inspired by the ion diffusion at the interface between the red glaze and glaze layers, which was confirmed by the study of overglaze painting on porcelain test pieces, we developed frits with compositions in which a lime glaze was systematically added to a lead-free multicomponent alkali borosilicate glass frit. When the mixed powder of the frit and hematite was heat-treated, the excessive reaction with hematite was suppressed as the lime glaze content increased, due to the increase of the frit viscosity. The dissolution of hematite was suppressed in the sample with the same viscosity at a higher heat treatment temperature, i.e., with a higher lime glaze content, confirming that the composition of the frit strongly affects the dissolution of hematite. We attempted to improve the chroma of lime-glaze-added samples, and the highest chroma in this system was achieved by adjusting the amount of initial hematite and heat treatment temperature.

Automated summary

By studying the ion diffusion at the interface between glaze layers, we developed a glass frit composition with added lime glaze for improved results in the ceramic industry. This addition effectively suppressed excessive reaction between the frit and hematite during heat treatment, resulting in improved dissolution control of hematite. The composition of the frit also influenced the chroma of the lime-glaze-added samples.