Elastic recovery, or resilience, is a measure of the ability of an elastomer to return to its original shape when a compression load is removed.

Ideally a seal should have a good resilience which can be largely controlled by compounding. It is a peculiarity of many elastomers, however, that resilience can vary widely with temperature, and with a sharply defined minimum value which commonly occurs in the range of –20 to +20 °C. Some elastomers, notably silicones, retain substantially constant resilience over a wide range of temperatures.

A low rating is desirable for dynamic seals, where recovery is important; this may refer to compression set or tension set and is a measure of the permanent change in original dimension after being compressed, or stretched, under compressive or tensile loading, respectively.

Compression Set is significant in that because most seals are loaded in compression some permanent reduction in dimension or shrinkage will occur, by the amount of set characteristic for that material. This may, however, be offset by other factors, such as swelling of the seal in contact with the fluid or can be allowed for in seal design.

Excessive Tension Set may result in a seal ring being a loose fit after being stretched in place over a rod because the seal does not recover to its original inside diameter to which the groove was matched. This would probably be offset by compression set on completion of the assembly and so tension is normally ignored.

The latter may be significant in plastomers which have low elongation and slow recovery, particularly if over-stretched. Both elastomers and plastomers, however, if loaded in tension, or with residual tensile stresses, will tend to contract with an increase in temperature.