Sulphate partly reacts during batch melting, dependent on the presence of reducing agents in the glass forming batch. These reactions cause early sulphur losses from the batch or primary melts, thus it reduces the sulphate content available for fining of the fresh melt. The fining mechanism of sulphate containing glass melts is described & a simulation model is derived to calculate gas evolution from thermodynamic properties of gases & fining agents in glass melts at equilibrium conditions. Modelling results have been validated by experimental data, comparing modelled gas evolution with experimentally observed bubble size changes during fining. The model & experiments are consistent for the determined fining gas evolution, & sulphate retention after fining.
