This report covers the results of a general study of the effect, of various physical and chemical factors upon the oil separation (bleeding) tendencies of greases. Where possible the results were examined on anmathematical basis, but in many cases no exact relationship could be established. Bleeding was increased by an increase in temperature or pressure but not proportionally in all cases. Increasing the oil viscosity, soap percentage, additional millings, and aging of the grease, all tended to reduce bleeding. The chemical composition of the thickener and the consistency of the grease did not seem to have any consistent effect. The construction of the test cell had an influence in that a thicker grease layer reduced and a finer screen increased the bleeding. Radioactive tracer studies disclosed, that during gravity bleeding of a grease the oil-soap ratio remained constant throughout the grease mass.
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