There are specific models about the influence of shear on mixtures that are distinctive from dspersions of unifom particles. Understanding the flow behaviour of mixtures of colloidal particles is crucial to many practical applications where the end structure is determined by process conditions. For example orthokinetic aggregation that might involve heteroflocculation is thus of considerable interest in theory and practice. This proposal will address these questions by making basic principles studies of model systems composed of isotopically labelled polystyrene latex.