The character of phase transformations in glass mixtures at all stages of their preparation, including moistening, compaction and drying, has been studied, and criteria for evaluating the formability of glass mixtures have been proposed. The interrelation of the main technological parameters of the granulation process (moisture, duration of granulation and mechanical strength of granules) with the proposed criteria is established and the possibility of their use for choosing a method of compaction of charges and the conditions for its implementation is shown. Tab. 1, ill. 3, bibliography: 7 titles.