What is % Compression Set?
Percent compression set is a measure of the permanent deformation of foam after it has been compressed between two metal plates for a controlled time period and temperature condition. The standard conditions are 22 hours at 70o C (158o F). The foam is then compressed to a thickness given as a percentage of its original thickness, usually 50%. Compression set is expressed as the percentage of its original thickness that remained set. For example: If a 2 x 2 x 1 sample measured 1.00 inch before compression and 0.95 inch after the test, it is reported to have a compression set value of 5%, i.e., it did not recover 5% of its original thickness.
