ISO 4629-2-2016 standard specifies a method for the determination of hydroxyl values in Paints and varnishes using the Titrimetric method of catalysts. The hydroxyl value is a measure of the hydroxyl content in Resin, which is crucial for the performance of Coatings. This method is superior to traditional catalyst-free methods, with lower solvent consumption and faster reaction speed. The standard applies to the determination of hydroxyl values in various Resins, paints and varnishes, providing a scientific basis for quality control and formulation adjustment of Coatings.