National Standard for Coating Viscosity Determination [Rotational Viscometer method]

The viscosity measured by the Flow Cup method for thixotropic coatings is too large, and a Rotational Viscometer is required. There are rotary paddle viscometers, coaxial drum Rotational Viscometers, conical plate viscometers, etc.

In the national standard, the method standard for measuring the viscosity of coatings by Rotational Viscometer is commonly used in GB/T 9269---1988 Determination of viscosity of architectural coatingsStoner viscometer method and GB/T 975 1-1988 Determination of viscosity of coatings at high shear rates.

GB/T 9269-1988 is suitable for the determination of the viscosity of architectural coatings, and can also be used for the determination of the viscosity of suitable coatings. It is expressed in terms of the load required to generate a speed of 200 r/min in grams (g) and can also be obtained by checking the table in GB/T 9269---1988 and the load required to generate a speed of 200 r/min and Krebs units (KU) conversion. Krebs units (KU) are a logarithmic function of the load required to generate a speed of 200 r/min and are generally used to express the viscosity used for brush and roll coatings.

In GB/T 9751-1988, the kinetic viscosity of coatings is determined at a shear rate of 5 000-20 000 s, and the shear rate should be roughly the same when comparing the viscosity of various coatings. This standard applies to all brush paints, regardless of whether they are of Newtonian nature. Rotational viscometers and conical plate viscometers can be used in this standard. For the same experimenter, the relative error between two measured values obtained by using one device in the same laboratory should not be greater than 5%.

Comparison of 4 methods for determining the viscosity of coatings