Technical Terms Glossary
Density
Defined as the weight per unit volume. Measured in kg/m³. One of the most important features of foam is density which effects durability and support strength of the material. Foams with higher densities maintain their original features longer.
Firmness / ILD - Indentation Load Deflection
The firmness of a foam is its deflection against 40% pressure. Firmness is independent of density and is directly associated with the formulation. It is measured in Newtons.
Support Coefficient / Sag Factor
The support coefficient is the ratio of the force(a) necessary to squeeze the foam from 25% of its volume to the force (b) necessary to squeeze it to 65%. This is a value that is especially important for foam used in the seating parts of furniture. Density and SAG FACTOR are directly related. Having a high Support Coefficient means that along with a feeling of softness upon sitting, the foam will provide a continued feeling of support while sitting.
Compression Set
Compression is the deformation of foam under controlled heat within a certain period of time. This data provides information regarding how much deformation has taken place as a % unit based on original thickness after being in use for a certain period of time.
Tear Strength
Tear Strength is measured as the foam’s resistance to tearing. Unit of measurement is in Newton.
Tensile Strenght
Tensile strength is measured as the foam’s resistance to breaking off. Unit of measurement is in Newton.
Speed of Burning
Speed of burning shows how fast flames progress within a certain period of time in the case of burning foam. Unit of measurement is mm/sn.