 Since the time taken for the titanium film to react depends on a number of factors (such as the composition of the residual gas, the temperature of the chamber and the total pressure), the period between successive sublimations requires some consideration.Typically, the operator does not know all of these factors, so the sublimation period is estimated according to the total pressure and by observing the effectiveness of the outcome.Some TSP controllers use a signal from the pressure gauge to estimate the appropriate period.