Limitations of Measuring Viscosity Using Viscosity Cups
Although the Viscosity Cup is very convenient to use, it also has certain limitations. Because the Viscosity Cup cannot obtain the data of the shear rate, let alone control the change of the shear rate. In addition, as the liquid level of the coating sample gradually decreases during the viscosity measurement process, the shear rate will also change due to the change of the static hydraulic pressure. For example, when measuring the viscosity by painting 4 cups, the viscosity value of the general paint is 40-150s, but when encountering the thixotropic paint, the viscosity measured by this method will be too high. Therefore, Viscosity Cups can only measure relatively approximate viscosity data. If the paint sample is a non-Newtonian fluid, changes in shear rate will inevitably lead to continuous and significant changes in viscosity during the measurement process. This is why the viscosity value measured by the Viscosity Cup is defined as the kinematic viscosity value.
