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What does a red, blue, green, white or even pink grease tell you about that grease? Does it imply certain types or additives? Different levels of quality or cost? These are all common questions, and they can all be answered in one word: no. Or, more specifically: not necessarily. You see, red grease, while it may imply high temperature grease, such as Badass High Temperature Red Grease from a supplier like Delta Fuel. But another supplier offering a different brand of grease might also have a red grease with a completely different purpose, formulation and additive package.
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. One benefit of a grease with a distinctive color is that it 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. This can be a helpful indicator, but grease color alone should never be used to identify a grease (unless you are certain that only one particular grease of a certain color is used in your facility).
The table below shows how a particular grease color may refer to several different types of grease, especially among lithium-complex greases.
The color of grease can also provide some indication of its overall quality—not that red grease is always higher quality than black grease, but if your grease that started out red begins to look darker and darker until it turns black, its color is telling you something about the grease's current quality: degraded.
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.
Besides grease darkening due to operating and environmental conditions, a shift in color could be a sign that the grease has mixed with a different type of grease unintentionally. If this occurs, immediate action should be taken to determine how and why this has happened. Careless greasing with the wrong grease is more common than most people realize, and the effects of grease mixing are very bad for machine reliability and grease performance.
A quick solution would be to use different types of fittings for various types of grease, such as normal fittings for stand-alone bearings and button-head fittings for electric motor bearings. Another option would be to leave a dollop of grease remaining on the grease fitting to indicate the appropriate color. But remember, this method should be used only when there is a single type of grease at the facility with that particular color. The grease type and color should also be marked clearly on the grease gun.
Remember, while the color of grease may have the potential to provide quality information, it is only intended as a branding to indicate the type of grease (usually by thickener type.) However, keep in mind that no grease color is guaranteed to specify a particular thickener type even within a single grease supplier or manufacturer’s offerings.