Grease types sodium-soap greases

Since 1977 several new thickener types have become widely used, including complex (sodium, lithium, calcium or aluminium), polyurea, modified clays, and other non-soap thickeners. To bring the picture up-to-date, Risdon carried out an evaluation in 1986 of three of the newer grease types not inciuded in the previous programme. They were lithium complex, aluminium complex and polyurea. They included one EP (extreme pressure) and one non-EP grease for each type of thickener, and all were of the same consistency grade, NLGI No 2. 

Heavy-metal soaps (loosely called metallic soaps) are those formed by metals heavier than sodium (aluminum, calcium, cobalt, lead, and zinc). These soaps are not water soluble specific types are used in lubricating greases, gel thickeners, and in paints as driers and flatting agents. Napalm is an aluminum soap. See saponification detergent. 

Methods of analysis (ASTM D-128, IP 37) are available for the measurement of excessive acidity derived from oxidation. These methods cover conventional grease that consists essentially of petroleum oil and soap. Thus these test methods are applicable to many types but not all grease. The constituents covered by the test series are soap, unsaponifiable matter (base oil), water, free alkalinity, free fatty acid, fat, glycerin, and insoluble. A supplementary test method is also provided and is intended for application to grease that contains thickeners that are essentially insoluble in n-hexane and to grease that cannot be analyzed by conventional methods because of the presence of such constituents as nonpetroleum fluids or nonsoap-type thickeners, or both. These methods may not be applicable to grease analysis when lead, zinc, or aluminum soaps are present or in the presence of some additives such as sodium nitrite. 

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