Measurements of Coating Colors

The shear-viscosity and viscoelastic properties of paper coatings and their time-dependent behavior are important attributes that need to be measured for better understanding and optimization of the process. 

Viscosity is measured with rheometers or viscometers. The methods used include rotational deformation, squeezing deformation, extrusion (capillary) flows, and free surface stretching. For rotational instruments, there are two modes of operation controlled strain and controlled stress. Rotational measurements can be further subdivided into different measuring methods (flow, oscillatory, stress relaxation, and creep) and different measurement devices (spindle, cone-and-plate, parallel plate, concentric cyhnder). As for a capillary rheometer, there are two modes of operation controlled flow (strain) and controlled pressure (stress). 

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