A class of structured particles is developed such that the effects of particle interactions are adjusted enabling suspension mechanics to be studied without the influence of interparticle forces other than volume exclusion, Brownian and hydrodynamic interactions. Three grades of these near-hard structured particles are developed from fumed silica. These particles have the same structure as measured by the mass fractal dimension. Stress dependent viscosities and diffusivity measurements are reported as a function of particle concentration, providing an opportunity to determine the scaling behavior of these properties with the two characteristic sizes: the primary particle and aggregate sizes. Except at stresses exceeding the critical value demarking the onset of shear thickening, flow curves superimposed with each other and with hard sphere suspensions compared at the same effective packing fraction, phi/phi(m). (C) 2004 The Society of Rheology.