Abstract The stability characteristics of mixed aqueous dispersions of titanium dioxide and mineral oil emulsion droplets are examined as a function of pH and emulsifier type and content. Knowledge of such behavior is important to strategies for conversion from solvent-based to water-based coatings. The practical goal is to determine conditions leading to selective coagulation between the oil droplets (binder) and pigment particles. Zeta potentials of both the titanium dioxide and the mineral oil particles are measured under all conditions to identify regions of expected heterocoagulation and to quantify the electrostatic boundary conditions. The latter are used in the numerical solution of the pair interaction potentials based on the recent theory of McCormack et al.( J. Colloid Interface Sci. 169,177, 1995). The potential functions are used in a modified version of the stability model of Hogg, Healy, and Fuerstenau ( Trans. Faraday Soc. 62,1638, 1966) to calculate early-stage aggregation rates. Photon correlation spectroscopy is used to determine stability ratios for homo- and heterocoagulation, and initial results indicate good agreement between experiments and computations.