Polyurethane Foam ILD and Density

[phoenix]

Hi a2dox,

Would a 6 inch thick 2.4# polyurethane foam core that is 35 ILD feel the same (in terms of firmness) as a 6 inch thick 1.8# polyurethane foam core that is 35 ILD? Obviously the 2.4# would be more durable, but is there a difference in the feel, even with the same ILD numbers? If there is a difference, which would feel firmer?

There is more about the different specs that can affect how soft or firm a foam feels in post #4 here. The two most important of these would be the ILD and the compression modulus although there are also other foam properties that will affect the “feel” of a foam material as well outside of just its softness/firmness that are more subjective.

Depending on how deeply it was compressed … a polyfoam layer that has a higher compression modulus would start off feeling softer and then become firmer faster as you compress it more deeply than another layer of polyfoam that was the same thickness and ILD/IFD and would tend to feel firmer if it was compressed more than 25% (which is the percentage compression that ILD/IFD is measured) and would also feel softer if it was compressed less than 25% of its thickness. Higher density polyfoam will tend to have a higher compression modulus than a lower density polyfoam…

Phoenix