The aggregates for two types of fumed silica are compared with each other and with colloidal silica similar to one used as a spacer additive for toner. These examples of fumed silica differ in that one is made up of very large (sub-micron) sized primary particles with a low degree of aggregation while the second fumed silica example has a much higher, balanced, degree of aggregation. The aggregates of both forms of fumed silica disperse on a toner surface to result in effective particle diameters larger than the colloidal silica particle. Also, because of their fractal morphology, these dispersed aggregates are more likely to remain fixed on the toner surface as compared to the colloidalbased additives.