ISO 8502-6 is an international standard on the use of the Bresle method to determine the surface cleanliness of steel surface preparation before painting. The standard specifies a method for determining the surface cleanliness of steel surface preparation before painting using the Bresle method under specific conditions to ensure mass and adaptability of surface preparation. The standard specifies experimental equipment, experimental procedures and data processing methods. Specifically, the standard requires the use of the Bresle method to extract water-soluble contaminants on the surface preparation of steel surface preparation before painting under specific conditions, and then to determine the content of contaminants using appropriate analytical methods. The standard also specifies accuracy and Reliability requirements for the determination, and the manner in which test results are reported.