Low Density Foams

[phoenix]

Hi SleepyAl,

I’ve researched a number of mattresses and came across a few mattress retailers who offered a fairly high quality comfort layer, however, had a transition/base layer that was less than 1.8lbs. I can’t remember where i read on this forum but I was under the impression that 1.8lbs was the suggested lowest density that a foam mattress should have.

I believe you are referencing the durability guidelines here. For a one-sided mattress, I recommend a minimum of 1.8 lb. density for polyfoam, unless it is a very thin layer of “just an inch or so”. For a two-sided mattress, 1.5 lb. density would be the minimum I recommend for polyfoam. These would be my recommendations for a more durable product.

When I asked the retailer about the low density of the bottom layers of their mattress, they had suggested that density is not the ultimate metric when it comes to durability and suggested that there are a number of other factors to look at such as tensile strength, etc. Is there any truth to this or is this just marketing spin?

While there are certainly many ways to address the performance characteristics and durability of polyfoam, density is by far the best predictor of durability. The higher the polymer density of a foam, the better the foam will retain its original properties and provide the support and comfort that foam was originally designed to produce.

IFD is a measurement of foam firmness. Support Factor compares different IFD measurements and details the foam’s ability to provide support. There are several Flex Fatigue tests that help to determine the durability of polyfoam, such as Roller Shear, Tear Strength and Hysteresis. But overall, foam density is the most important indicator of polyfoam performance with regard to comfort, support and durability (the more polymer material used to produce the foam, the better the foam will retain its original properties).

There is a little more reading about foam and durability here, here, and here.

Phoenix