The depth of the rotor immersed in the liquid and the effect of air bubbles.
The rotational viscometer has strict requirements on the depth of the rotor immersed in the liquid and must be in accordance with the requirements of the specification (some binocular instruments have strict requirements on the amount of liquid used for the test and must be taken from the cylinder).
When the rotor is immersed in the liquid, bubbles are often present. Most of the float will disappear after the rotor rotates. The bubbles attached to the lower part of the rotor sometimes cannot be eliminated. The presence of bubbles will cause a large deviation in the measurement data, so the tilt Slowly immersing the rotor is an effective way.