The ISO 4629-3 standard provides a rapid test method for the determination of the hydroxyl value of gluing agents for Paints and varnish. The hydroxyl value refers to the amount of hydroxyl (-OH) groups in gluing agents and is commonly used to evaluate their reactivity and performance. The standard provides an efficient and reliable technical means for determining the hydroxyl value in a short time through a simplified rapid test method. The standard specifies the reagents, equipment, operating procedures and data processing requirements in detail to ensure the accuracy and repeatability of the test.