ISO 11127-4 is part of the test method for non-metallic abrasive cleaning of steel surface preparation sand blasting before painting, this part is to assess Hardness by glass slide test. This standard specifies the method for evaluating Non-metallic abrasive Hardness during sand blasting cleaning to ensure abrasive mass and adaptability. The standard specifies experimental equipment, experimental procedures and data processing methods. Specifically, the standard requires that abrasive be tested using glass slides under specific conditions and then the abrasive Hardness is calculated.