In high volume liquid toner printers, a liquid toner supply should be continuously replenished. We provide a simple process physics diagram relating toner properties to developed mass and printed density. We describe three toner control and replenishment methods that have been used in previous products. We show print density and toner property data from a long print test using an experimental set of inks. We use regression analysis to analyze the adequacy of the three known replenishment methods. The analysis shows ink to ink differences and also identifies cases in which the known replenishment methods are insufficient to maintain constant output print quality.