Standard Bench Viscometry for Aqueous Paper Coatings
Bench viscometry qualifies low-shear slurry pumping and leveling, requiring tight thermal control and correct spindle torque to prevent coater runnability failure.
RV Spindle
Rotating Element
Mechanical testing of high-viscosity fluids requires a robust immersion object designed to generate measurable resistance when rotated. Viscometers utilize an RV spindle to measure the torque required to turn through coatings and adhesives. This component is designed to handle a specific range of fluid resistance.
Drag Measurement
Surface area dimensions on the rotating tool determine the amount of viscous drag encountered in the sample. A larger disc generates higher resistance, whereas a narrow cylinder is better suited for very thick mixtures. Accurate calculation of apparent viscosity depends on matching the rotational speed to the specific limits of the RV spindle.
Standard test procedures require that the spindle be fully submerged to the designated immersion groove to prevent measurement errors.
Calibrated Application
Quality labs in board mills rely on these devices to test the consistency of starch solutions and barrier coatings before they reach the production line. Because the RV spindle is calibrated to high tolerances, it allows converters to compare adhesive performance across different factories. If the spindle receives damage or bends even slightly, the test results will drift, resulting in incorrect readings of fluid flow.
Routine verification against certified reference oils ensures that the viscometer and spindle remain in perfect calibration.