Memory Foam Ain't What It Used To Be

[phoenix]

Hi Walt,

We’ve been memory foam fans for over 15 years now, but that’s changing. It seems that all the memory foam manufacturers these days offer only soft-to-medium memory foam. If you want firm, you can get it in the foundation layer, but not in the memory foam layer.

There have always been “firm” memory foam mattresses but there has never been any particularly “firm” memory foam. Firm memory foam mattresses generally use thinner layers of memory foam so that the firmness of the layers underneath it “come through” more. This is why memory foam has never been used in support layers because it’s not firm enough to be suitable as a support material … only as a comfort or transition layer.

ILD with memory foam isn’t particularly meaningful because the ILD of memory foam changes with heat, humidity, and the length of time it is continuously compressed and there are many other factors that contribute more to the firmness level of a mattress than just the ILD of the material … particularly with memory foam (see post #4 here). There is also more about the different properties of different types of memory foam that have always been independent of density but that can affect how firm it feels in post #8 here and post #9 here.

What is true is that much of the memory foam being sold today has a faster response and is less temperature sensitive which can both affect how firm a memory foam layer feels as well.

Further, it used to be that you could judge firmness by density, but that corollary no longer holds true. Nowadays, a 5.3 lb density memory foam layer could be soft or medium, but it’s never firm (as far as I’ve been able to find).

This has never been particularly true because any density of memory foam can be made in firmer or softer versions. For example the Tempurpedic 7 lb memory foam feels softer than the Tempurpedic 5.3 lb memory foam and there are also several versions of the Tempurpedic 5.3 lb memory foam that have different firmness levels as well even though they are the same density.

Or if they do tell you, it’s only in the 10-20 range, which qualifies as soft.

Memory foam ILD’s don’t relate or compare to the ILD’s of other fast response materials because the method that is used for testing ILD produces different results with slow response materials than with fast response materials. Memory foam has always been in “soft” ILD ranges under 20 which again is why it has never been used as a support layer.

This really sucks if you want true support from the memory foam layer.

Again … memory foam can only be used as a comfort or transition layer and its strength is as a pressure relieving layer … not as a support material. It has always been too soft to use as a deeper support layer in a mattress. There is more about primary support, secondary support, and their relationship to pressure relief in post #2 here and in post #4 here that may be helpful in understanding the difference between support/alignment and comfort/pressure relief.

What you may be looking for is some of the older style memory foam that is more temperature sensitive (takes longer to soften and feels firmer because of this) and has a slower response than many (but not all) of the newer types of memory foam. Much of this was in response to the complaints about many “old style” memory foam mattresses with temperature regulation and a feeling of being “stuck in the sand” which makes it difficult to change position. There are still many “firm” memory foam mattresses available though and because there are more manufacturers that are making memory foam mattresses than there used to be … there are also more “firm” memory foam mattresses available than there used to be as well.

Phoenix