Paint viscosity testers are viscosity meters to determine the viscosity of liquids. The flow cups are often used in industry and research laboratories. Due to the form of the measuring method, however, the determination is only carried out on low-viscosity liquids, since the liquid cannot run off through the nozzles if the viscosities are too high. Liquids with Newtonian behavior therefore give the most accurate results in the flow cup. The viscosity can be determined on the basis of the flow volume and the measured time that the liquid needs to run through the nozzle from the flow cup. The start time begins when the liquid emerges at the lower edge of the nozzle. It is stopped as soon as the liquid no longer flows evenly or the liquid breaks off. In addition, there are immersion cups that are suitable for quick measurements on site; these are only immersed in the material to be measured. As soon as you lift out the cup and the liquid comes out of the nozzle, you can start timing. After completion of the measurement, it is imperative that the flow cup is cleaned, as dried-on residues can falsify the next measurement result. It should also be ensured that no pointed or sharp tools are used for cleaning. Scratches and scrapes in the flow cup also affect the result.