Foam is described by density; this is how we simplify the classification of foam quality. The heavier the density of foam the better the quality of the foam you have. There is however other ways on how softness and elasticity are measured.
Following the manufacturing process, foam is tested for density, resilience and hardness.
Density: The weight of foam per cubic meter;
Hardness: Measured by the pressure applied to 40% of the foam thickness; and
Resilience: Measures the Elasticity and bounce back qualities, providing how long lasting the foam will be.