Summary: The calcium grease is designed for lubricating of joints and can be used in slow speed bearings and other friction mechanisms working at low pressures, normal to high humidity and temperatures between -20°C to 50 (60)°C.
It is a soft oily lubricant with yellow, light brown or dark brown color. It is prepared by reaction in situ in an environment of middle viscosity mineral oil of the fats and / or fatty acids, calcium hydroxide (lime) and a small amount of water.
It is one of the first industrially produced greases. In some countries this is one of the most widely used and cheapest greases. Water is necessary to stabilize its structure. Due to its evaporation calcium grease is sensitive to elevated temperatures. The process of dehydration starts at about 80°C, so the operating temperature must not exceed 65-70°C. Above 95-97°C the grease melts. At lower temperatures (70-80°C) the grease can also leak out of the bearings, as its penetration is increasing too many (grease softened). When the grease loses its water, it structure destroys and the two phases (mineral oil and the calcium soap) separate. This is not its only disadvantage. It is not suitable for lubrication at high speed. At high revs and / or temperature, the lubricant loses its quality. Another disadvantage of it is, that after a destruction through exposure on high loads and stress, the hydrated calcium grease recovers its initial properties to only 30%, while this index by modern greases is far higher. The hydrated calcium grease has its benefits too - despite the significant temperature limitations, it does not emulsify with water and has a very good resistance to wash out. Moreover, its production costs are relatively low. It is believed that in case of wetting of the lubricant with water even up to 5%, it does not lose its properties, though such a high water content is not permitted by the standards. Another improper impact on which the lubricant withstands relatively well, is the influence of the oxidized oils on it. While a lithium grease would be destroyed seriously, the calcium one would reduce its penetration due to mixing with oil (would soften), but probably nothing else would happen. The hydrated calcium greases have a very good colloidal stability. Even during prolonged storage, they do not separate oil. It is possible that they harden in some degree after manufacturing (so called thixotropic hardening). After intensive mixing they recover their penetration. Although in some cases the hydrated calcium greases are used as conservation (corrosion protective) lubricants, such use is not recommended. First - the grease could not be melted, and the workpiece immersed, so as to obtain a dense film. After the film is applied by daubing, it is not dense and the conservation is compromised. Its qualities are also far inferior to the best conservation lubricants.
The calcium grease is intended mainly for lubrication of units, operating under milder conditions, or exposed to water, and where it is needed as protection from jamming - for example in industry, agricultural equipment and others. It is used for the lubrication of threaded connections, small gears, springs, chains and plain bearings, joints and other friction mechanisms and parts, working under medium pressure and low speed. This hydrated grease has good low temperature properties, however, is strongly not recommended to be used at temperatures above + 70°C (the recommended highest operating temperature is lower with 10°C), therefore, that the small amount of water contained in the lubricant, which stabilizes its structure, begins to evaporate and the structure of the lubricant breaks.