**3. Results**

## *3.1. Pristine Grease*

Initial testing was performed on the pristine grease to study the variation in contact angle with different grades of lithium-based greases. Greases were sheared in the grease worker for 60 strokes, and the worked penetration values were determined using a penetrometer. Figure 6 shows the results of the contact angle measurement as a function of the worked penetration. From this figure, the existence of a linear correlation between different NLGI grade greases and contact angle values can be observed.

**Figure 6.** Worked penetration vs. contact angle for different NLGI grade grease.
