Hi Cloudz,
I would be surprised as well. Where did you come up with the value of a 2.8 lb polyfoam, as this is not a common density except in some of the newer generation of what I call “high performance” polyfoams? Unless you are very experienced with foam manufacturing, fabrication and mattress design (which would be a very small percentage of the population), I’d avoid making specific foam density specifications in particular layers, and instead reply upon the manufacturer’s knowledge of mattress construction and then compare their specifications to see if they meet the mattress durability guidelines here, and then perhaps request a foam of a higher-density in a certain layer if you found a “weak link”. A 1.8 lb polyfoam would be considered a good and durable material in a two-sided mattress.
On their web site, Springmade doesn’t list the specifics of their mattresses, so you’ll need to acquire the information listed here so you can compare the quality of the materials and components. And be sure to follow the steps as outlined in the mattress shopping tutorial, which I’ve linked to previously, for testing a mattress.
Good luck!
Phoenix