Abstract Ananalysis is made of the types of adverse behavior encountered in compounding and fabricating dry-mixed elastomers on a factory scale, with an attempt to ascribe the different modes of behavior to semifundamental properties of the elastomer and its compounds. On the basis of this analysis, four simple tests—filler stiffening, compound viscosity, length shrinkage, and rugosity—are proposed for determining the processing properties of elastomers on a laboratory scale. Extended correlations of predictions made from these tests with factory data demonstrate their reliability and usefulness in laboratory evaluation of new rubberlike materials. Much of the background information referred to in this and the following paper (page 833) was accumulated by the rubber industry at large working on the government-sponsored rubber program through the Research and Development Section, Rubber Reserve Company, and therefore has been subject to the usual secrecy orders. For this reason much of the earlier literature has not been published in the usual channels. However, every effort has been made to recognize contributions, made but not released, by other investigators by reference to their names and organizations.