The glass melting process can be broadly divided into five stages: silicate formation, glass formation, clarification of the molten glass, homogenization, and cooling.
The silicate formation stage is completed at 800–900℃, where the batch material becomes an opaque sinter. The glass formation stage ends at around 1200℃, where the sinter melts into a transparent molten glass. The clarification stage occurs at 1400–1500℃, where the viscosity of the molten glass decreases and air bubbles are eliminated. The homogenization stage uses diffusion and other processes to homogenize the chemical composition of the molten glass. The cooling stage lowers the temperature to achieve the required viscosity for forming. These stages are interconnected and influence each other, and in actual melting, they often occur simultaneously or alternately. Depending on the equipment, in a tank furnace, these five stages occur in different spaces at the same time, while in a crucible furnace, they are completed in the same space at different times. Modern tank furnaces are often divided into two main stages: batch melting and molten glass refining.
