The kinetic and equilibrium factors affecting the rate of precipitate flotation are analyzed by means of the Gouy-Chapman model. Kinetic effects are found to be extremely rapid, and the rate of precipitate flotation is due to equilibrium considerations. Removal efficiency as a function of inert salt concentration goes through a maximum at about 10−5Mfor films 300 Å thick. Removal efficiency increases with increasing zeta potential of the film surface and with increasing charge on the precipitate particles.