The ISO 2431-2019 standard describes a method for measuring the flow time of Paints and varnishes using a flow cup. The standard specifies four flow cups with different pore sizes for a wide range of viscosity samples. The procedures for checking abrasion with flow cups are updated in the standard and guidance is provided for measurement in fume cupboards. The method is mainly used to control and confirm the consistency of coatings and is not suitable for materials with non-Newtonian flow characteristics. By standardizing the design and testing methods of flow cups, the standard aims to improve the accuracy and comparability of flow time measurements.