That surprises me. I used to work with this foam when I helped build driving systems for for people in wheelchairs or with other mobility limitations and I didn't know that.

We used different densities for different purposes. I always assumed the softer foam was a lesser quality because when it got even a little warm it seemed to lose almost all of it's visco-elastic properties. It became so soft that it provided almost no real cushioning of distribution of weight.

But I didn't pay the invoices for the sheets we purchased, so I never knew the cost difference. I recall that we had three different densities to choose from.

Now we have a memory foam mattress and I don't really like it. I think it uses a soft foam and when it warms up it sags like wet noodles. Feels great when you first get on it, but you end up with the same thing as you get sleeping long-ways in a hammock.

So, I'd like to ask a few questions if you don't mind...

Does the higher density foam retain a higher level of support as temps increase?

Is there a cost difference in the densities?

What is the weight difference?

I know they all broke down with age, exposure to air, and light. Is there a normal life expectancy for this stuff?

What qualities are superior in the soft foam?

I 'm just curious, you don't really need to answer these questions, they've just been hanging there nagging me when I think of applications for this stuff. For example, I got my Singer 99 last year and I'm looking at it thinking a project like a backpacking pillow might be something I can handle <img src="/forums/images/graemlins/grin.gif" alt="" />

Bill