Compression set

The term is normally applied to soft materials such as elastomers and foams.

[2] This has the formal name compression set under constant force in air.

CA, the compression set A is given by CA = [(to - ti) / to] * 100 where to is the original specimen thickness and ti is the specimen thickness after testing.

[2] This has the formal name compression set under constant deflection in air.

The specimen is compressed to 75% of its original height for a set time and at a set temperature (sample is compressed to .75 of its original height).