The primary difference in production between conventional calcium-base grease and anhydrous calcium-base grease (sometimes referred to as high-quality calcium-base grease) lies in the hydration step: for conventional calcium-base grease, the hydration process is a unique and essential stage—dictated by the inherent characteristics of the grease itself—that is absent in the production of anhydrous varieties.
For illustrative purposes (provided for reference only), consider the production of conventional calcium-base grease: once the saponification and dehydration stages are complete, cooling water is circulated through the reactor jacket to lower the temperature in preparation for hydration. The hydration process typically commences within a temperature range of 110°C to 125°C. The amount of water added during hydration generally constitutes 2% of the total material volume within the reactor; this quantity may be adjusted slightly upward or downward depending on the specific product grade being manufactured. The water must be introduced slowly over a period of 25 to 30 minutes. Upon the initial addition of water, a phenomenon known as "reactor swelling" may occur—characterized by a rise in the material level and the generation of copious steam—necessitating continuous agitation; during this phase, the agitator speed may be reduced to approximately 30 revolutions per minute (rpm). However, as the temperature subsequently declines, the liquid level within the reactor will rapidly recede.
During the hydration stage, the precise quantity of water introduced directly impacts the quality of the final grease product. If insufficient water is added—preventing the calcium soap molecules from fully forming hydrates—the soap will fail to establish a stable structural matrix within the base oil; this results in the appearance of discrete soap particles within the reactor contents, often rendering the batch a manufacturing failure. Conversely, if excessive water is added, the surplus water will persist in the form of "free water." The resulting calcium-base grease will be excessively soft, exhibit a lowered dropping point, lose its characteristic translucent appearance in favor of a turbid one, and suffer a general degradation of its other performance properties.
In contrast, anhydrous calcium-base grease is formulated to form a finished grease product without undergoing any hydration process, thereby ensuring that the final product remains entirely free of water. Conventional calcium-base grease, by its very nature, invariably contains water.