- ISO 6914:2004 describes three methods for measuring the change of stress in a rubber test piece at a given elongation for the purpose of determining the ageing characteristics of the rubber vulcanizate: one for measurement under continuous strain conditions and two for measurement under intermittent strain conditions. The necessary calibration schedule for this type of measurement is included in Annex A. No agreement between the three methods should be inferred; the method used will depend on the purpose of the test. Measurements at a single elevated ageing temperature may be used for quality control purposes as a measure of heat-ageing resistance. Measurements at a number of temperatures may be used for research and development purposes to estimate long-term ageing characteristics, in accordance with the procedures described in ISO 11346.