The ISO 787-9:2019 standard specifies a test method for determining the pH value of aqueous suspensions of pigments and fillers. This method is suitable for evaluating the acid alkalinity of pigments or fillers when forming suspensions in water and has a wide range of applications. Major modifications to the standard include the reference to ISO 18451-1, the preparation method adjustment of Glass containers, and the update of wetting agent selection (including methanol). The standard provides standardized test procedures to ensure the accuracy and repeatability of test results, providing a basis for quality control and product development in related fields.