To coat automobile exteriors, making their appearance more attractive.
* While a particular model/version may be used as an example in this method, any current or past model/version from the same series may also be used. Please consult a sales associate to discuss the most current instrumentation and software available.
In our experiment we used the "Standard Test Method for Cone/Plate Viscosity at a 500 s-1 Shear Rate" as described in ASTM Standard D 7395 -07. This is a test method to determine the viscosity of paints at 500 s-1 using a Cone/Plate Viscometer. The test method calls for the material being tested to be at 25°C, and allows up to one minute for the material to equilibrate. The test method recommends using the solvent trap to help prevent evaporation of the material. For further detail on this test method refer to ASTM Standard D 7395-07.
We used a High Torque CAP 2000+L and a Low Torque CAP 2000+L viscometer, with Capcalc v3.0 software for automated instrument control and data acquisition. We used Cone 10 to achieve on-scale results, with 170 ?L of fluid. The cone and plate were cleaned before dispensing each paint portion. A fresh portion of sample was used for each trial. Three trials were done for each color of paint. We equilibrated the sample and cone for 35 seconds prior to testing. The solvent trap was used to help prevent evaporation. Representative data from the analyses are shown in Figures 1, 2, and 3 below:
Figure 1: White Auto-Refinishing Paint, at 25°C.
Figure 2: Black Auto-Refinishing Paint, at 25°C.
The tolerance for the High Torque CAP 2000+L Viscometer running at 100 RPM with cone 10 is +/-100 cP, and the tolerance for the Low Torque CAP 2000+L Viscometer running at 100 RPM with cone 10 is +/-4.4 cP. Figures 1 and 2 show that results obtained with the Low Torque CAP 2000+L and the High Torque CAP 2000+L Viscometer were repeatable within the tolerance of the viscometers.
Figure 3: Black and White Auto-Refinishing Paint Comparison
Figure 3 plots Run 1 of Figures 1 and 2. Figure 3 shows the great difference in the viscosities of Black and White Auto-Refinishing Paints. This difference required different viscometers to be used for each paint. For the black paint, we used a Low Torque CAP 2000+L Viscometer so we could achieve on scale results at a lower viscosity. For the white paint, we used a High Torque CAP 2000+L Viscometer so we could achieve on scale results at a higher viscosity.
Acknowledgement: We thank Clifford M. Schoff, Ph.D., for his helpful technical discussions concerning this work.