Hello all,
I talked with Tuft & Needle today and confirmed that the latest iteration of their mattress uses two layers vs three in their previous design. The top layer which replaces the previous two top layers they were using is a much higher density (about 3 lbs) and higher performance polyfoam similar to what I was describing in post #2 earlier in this topic. The foam itself is being formulated specifically for their criteria in consultation with their foam pourer/manufacturer.
It is a more point elastic and conforming material that is more pressure relieving and softer than their previous mattress and with only a single layer (and eliminating the glue between the previous top two layers) the transition and response curve between layers would be “smoother” as well. Because of the higher density and higher compression modulus of the foam (compression modulus is the rate that a material becomes firmer as you compress it more deeply) it is also more supportive than their previous version. It also has a higher airflow and is more breathable and would be more temperature regulating than their previous comfort layers as well. It would make sense that with the properties of this higher quality and higher performance polyfoam that it would be a better match in terms of PPP for a higher percentage of people than their previous mattress design.
Post #234 here also has some additional information about their new comfort layer and the fire barrier they are using as well.
They also changed the density of the deeper layers to a polyfoam support core that is about 1.8 lbs.
Phoenix