This International Standard describes three methods for the measurement of the change of stress in a testpiece at a given elongation for the purpose of determining the ageing characteristics of a rubber. —MethodA is intended for measurement under continuous strain conditions. —MethodB is the preferred method for measurement under intermittent strain conditions. In the case of both methodsA and B, a stress relaxometer is used to record the stress at the temperature ofageing. —MethodC is an alternative to methodB for measurement under intermittent strain conditions in which thetest piece is removed from the ageing environment for measurement of the stress at standard laboratorytemperature. The necessary calibration schedule for this type of measurement is given in AnnexA.Measurements at a single elevated ageing temperature can be used for quality control purposes as a measureof heat-ageing resistance. Measurements at a number of temperatures can be used for research anddevelopment purposes to estimate long-term ageing characteristics in accordance with the procedures described in ISO 11346. No agreement between the three methods should be inferred. The method used will depend on the purpose ofthe test.