As I understand it, foam blocks have a property called firmness, which is essentially, for a given % of height reduction, how much force does it take to achieve it. Firmness is measured using the force in kg necessary to reduce a foam sample of a specific height by 25% of it's original height, a measurement termed Indentation Force Deflection (IFD).
Suppose we had two foam blocks of different thicknesses, which are, apart from the thickness, identical. By thickness I mean, if you place them on a table, the thicker foam block has a greater height from the surface of the table than the less thick foam block.
My question is, does thickness affect the compressibility of the foam? Will having more foam make it harder to compress? If so, why?
This intuition came to me because I recalled, if I take a single piece of paper, it will tear quite easily if I rip it in half. But if I take an entire ream of paper, it will not tear easily and be much harder. So I was wondering whether a similar property existed here.