A method for controlling process conditions in a continuous skull nozzle process is provided wherein one or more process parameters are controlled to maintain the operation of the process within a process window derived using integral solutions and expressed in terms of dimensionless parameters. The process window defines a range of values for the controllable process parameters within which a steady state solidified skull will be maintained and outside of which a steady state solidified skull will not be maintained. A pressure differential between the inside of a crucible holding the melt and outside of the crucible is one process parameter which is controlled to adjust the melt discharge flow rate to maintain operation within the process window.