AbstractFlocculation of latex particles by a series of cationic polymers has been investigated, with special attention being paid to the effect of particle concentration. Both initial rate and ultimate extent of flocculation have been examined over a range of polymer concentrations, so that the onset of flocculation and of restabilisation could be established. At low particle concentrations, the effect of the polymers seems to be predominantly charge neutralisation; even high molecular weight polymers do not appear to form ‘bridges’, presumably because of the relatively flat configuration of the adsorbed polymer chains. However, at high particle concentrations, bridging flocculation may occur because adsorbed polymer chains require a finite time to attain their equilibrium configuration.Some practical implications of these findings are briefly discus