Coatings manufacturers use various methods for quality assurance/quality control or QA/QC. The devices are simple and low-cost. Data usually consists of one point, giving what essentially is a "go/no-go" test. However, greater competition in the markets, stricter customer demands for product tolerances and wider adherence to ISO (or other) standards, are driving the adoption of tests that provide more meaningful data at reasonable cost. Furthermore, the "one-point" tests are inherently limited, in that they cannot describe the material behavior over a range of shear rates that may be essential for proper product performance.
Many coatings, for example, are sprayed onto substrates - requiring very low viscosity at very high shear rates - but then must stay on the substrates without further dripping - requiring fast structural recovery and, therefore, high viscosity at essentially zero shear rate. Thus, an automated, multi-speed, rheological or viscometric test is appropriate. These concepts are discussed and a solution presented within this article.