Electroacoustic measurement with a zeta -potential probe offers a quick and accurate determination of the optimal dispersant dose required for preventing aggregation. The most important advantage of this method is its applicability to concentrated dispersions which eliminates dilution. Traditional methods based on the dilution protocol are often inadequate because dilution affects the g-potential value. It is shown experimentally how this method works on the example of various kaolin slurries at 40 wt %. In combination with acoustic spectroscopy, this method yields a complete and consistent characterization of the aggregation stability.