ISO 3384-2:2012 specifies two methods for determining the decrease in counterforce exerted by a test piece of vulcanized or thermoplastic rubber which has been compressed to a constant deformation and then undergoes temperature cycling.
Method A: The temperature is cycled at intervals between a high temperature for ageing and a low temperature for checking the sealing force at this low temperature.
Method B: The temperature is cycled continuously between a high temperature and a low temperature to introduce thermal stress in the test piece.
The counterforce is determined by means of a continuous-measurement system.