This standard specifies a method for measuring the flexibility of a paint film using a Flexibility tester, assessing its flexibility by measuring the minimum shaft rod diameter at which the paint film does not cause damage. The standard covers baseplate, material and instrumentation requirements, including shaft rod dimensions and perpendicular tolerances after assembly. Operational steps include sampling, baseplate processing and painting, drying of the test plate, and bending testing under standardized conditions. Test reports require detailed documentation of test product information, test conditions and results.