Glasses containing fixed mutual ratios of Al, B, Ca, Fe, Mg, Na, and Si were melted while varying the fluoride content. The effect of fluoride was to suppress the formation of non-fluoride-containing crystals in the composition range from 0 to 11 wt. % F; above 11 wt. % F, the formation of fluoride containing crystals began to define the liquidus temperature. The effect of fluoride on the liquidus temperature was quantified and used to predict the liquidus temperature of melts made from real radioactive wastes. Although the liquidus temperatures of the surrogate and radioactive glasses agreed well, the types of crystals formed differed due to slight compositional differences introduced by the waste stream.