I pray I don’t make this too long. I just don’t have the time or energy to over-elaborate, right now. Sorry if it seems like I am being overly simplistic or focusing too much on this or that spec etc… I just have a couple of questions regarding some (very enlightening) reading I have been doing on this site.
Differential vs Progressive
Diff and progressive design: I read your overview etc… on these and also read you telling another member that these are merely guidelines and not concrete designs that you would, for example, see a manufacturer list as a feature or spec. I’m not saying this right… let’s just say I understand what you were telling that member. My question is; Are these actually mattress designs that are black and white/this or that, or can one person’s differential be another’s progressive based on their weight, body type etc…
If one person of 100lbs lays on a mattress that has 3" of say, 4lb MF and never “sinks in” to the support layer, would this make the mattress a Differential design, as opposed to another at 200lbs laying on the same mattress and sinking well past the comfort layer and “borrowing” from the support layer(s). Does the same mattress essentially become a progressive? I am well aware of my “theory at a distance” problem, I’m just wondering if I have these definitions and their grey areas in perspective. The main thing I got from that article, in combination with others is that with memory or any other comfort layer, more is not better and just enough is the goal. Also, that memory foam has characteristics of air(low resilience?) And that is why too of thick layers of it causes lumbar support issues(my biggest complaint with beds)
This is why my Tuft n Needle + blind topper purchase has some problems, and ordering both at the same time would be unwise at best. The other problem is that most toppers are not returnable…
Support Factor/Sag Factor
Is support factor a spec that I should ask for when speaking to manufacturers? To what extent can it become a weak link? Or a “feature?” If I see a support layer labeled as HR foam, the manufacturer should be giving me a Support/sag factor of 2.5, otherwise it is mislabeled, correct?
Rocky Mountain Mattress (I think is one of your members), for example, boasts a 2.4 support factor in their support layers. Does this indicate HR Foam? I think you said HR must be 2.5. Is it safe to say they are using very high resilience HD Poly? Is that .1 A hard line between the two, or are these two products as close as they are on paper(an HD w/2…4 SF and an HR with 2.5 SF)?
I get the impression that you don’t consider HD Polyfoam a very ideal support material, at least in terms of durability. Unfortunately, it would seem that 90% of foam support layers are made of it, including those made by many of the member companies on MU. Is this simply a price trade-off that one has to make? If true HR foam is less expensive than latex, but more expensive than coils, why don’t we see more options using it? Is it just too close to latex’s price point to be relevant? Is it not worth it to them inject another price point/option between HD Poly and Latex, considering most consumers have not been enlightened by the MU?