Flow agents are widely used in industry, such as the plastics and pharmaceutical industry, to promote the flow of cohesive powders. Few studies of the quantitative effects of the flow agents on the flow of the powder have been reported. In this communication the effect of silica flow agents on the flow of a plastic powder is studied by means of avalanching behaviour. The avalanching behaviour of the powder as modified by the silica flow agents is summarized using descriptive parameters based on the calculation of fractal dimensions in data space and phase-space strange attractors. The structure of the strange attractors are shown to be statistically self-similar and effective descriptors of the change of theology caused by the presence of the flow agents.