1.1 ,These practices cover procedures for determining the liquidus temperature (T_L) of nuclear waste, mixed nuclear waste, simulated nuclear waste, or hazardous waste glass in the temperature range from 600°,C to 1600°,C. This method differs from Practice C829 in that it employs additional methods to determine T_L. T_L is useful in waste glass plant operation, glass formulation, and melter design to determine the minimum temperature that must be maintained in a waste glass melt to make sure that crystallization does not occur or is below a particular constraint, for example, 1 volume % crystallinity or T_1%. As of now, many institutions studying waste and simulated waste vitrification are not in agreement regarding this constraint (1).