Many types and combinations of thickeners and base fluids, along with supplemental structure modifiers and performance additives, give final grease formulations their special properties. The alkali or alkaline earth metal is in its elemental form or occurs as a hydroxide or oxide. The mechanical stability and rheological properties of the finished grease result from the fiber structure provided by the metal soap.
Water becomes available as a by-product during processing.
Thus, the manufacturing system itself is a convenient source of water. A small portion of the water formed by the saponification reaction may be retained during processing. This water hydrolyzes an equivalent amount of metal soap resulting in free carboxylic acid that assists in the dispersion of soap molecules. Larger quantities of water are sometimes incorporated into the molecular framework and become essential structural elements, as in the case of simple calcium greases. Particle size Increasing the amount of soap almost always produces a corresponding increase in consistency or stiffness.