The ISO 2 2553-4 standard specifies the compatibility requirements of Paints and varnish electrodeposition coating materials with liquid, paste and solid foreign matter. This part mainly focuses on the compatibility of electrodeposition coating materials when they come into contact with foreign substances (such as solvents, additives or contaminants) during the painting process, ensuring that the performance of coatings is not adversely affected. The standard provides the operation method and evaluation criteria for compatibility testing, helping manufacturers and users to identify and solve possible compatibility problems, thereby avoiding coating mass decline or unstable performance. Through the implementation of this standard, the uniformity, Stability and Reliability of electrodeposition coatings in complex application environments can be effectively guaranteed.