Article originally published on Noria.com.
Grease manufacturers use colorants simply to help facilitate the identification of greases and to make them more appealing, as opposed to just brown or black. Color can help users spot an incorrect grease if, for example, a certain color of grease emerges from a grease gun when another color of grease was expected.
The color of grease can also provide some indication of its overall quality. As grease degrades and becomes contaminated, it usually will begin to darken. This darkening, which can be more noticeable when compared to new grease, may be a sign that the grease has reached a condemning limit. Although it should not be surprising that grease darkens, the rate at which it darkens is the important factor.
(read the entire article, "How Color Can Indicate Grease Quality," at Noria.com...)
