Measurements of linear swelling in solvent of small test pieces provide a useful means of investigating anisotropy in vulcanized products and components whose small size precludes the use of conventional tests on dumbbells, etc. Anisotropy has been found to be present in molded components. The extent of this is related to the material flow in the mold before or during vulcanization. There also appears to be an effect of flow on crosslink density. In this preliminary investigation the contribution of each of the various factors, e.g., filler- filler structure, polymer gel, polymer-filler interaction, tendency to prevulcanize, has not been established.