ABSTRACT
The essential property that lubricating grease must possess is the ability to form a film between surfaces so that surface-to-surface contact is prevented. There have been many definitions of lubricating grease but perhaps the most simple is that used by the ASTM which defines lubricating grease in the following manner: "A lubricating grease is a solid or semi-fluid lubricant consisting of a thickening agent in a liquid lubricant". By selecting a suitable lubricant thickener and manufacturing procedure it is therefore possible to produce greases with specific properties. The properties that a grease system must possess are, in relation to the ability to form a seal, water resistance and the ability to resist relatively high temperature without undue softening or melting, properties largely determined by the thickener type. This can be illustrated by considering the soap greases. So far mention has been made only of the characteristics imparted to grease by using a particular thickener.
