Hi Odin2010,
Post #4 here has a list of suppliers for various components including several that sell a wide range of mattress covers.
@ Sleeping,
There is certainly legitimately “soft” Dunlop available (and some of the newer continuous pour Dunlop layers made by Latexco and Mountaintop can go as low as the low or mid teens) … it’s just much less commonly seen with molded Dunlop (although some of this is fairly soft in a few instances as well). I wouldn’t consider it to be less durable than Talalay in an equivalent ILD though. Some Dunlop pillows also have an ILD of under 10 although you won’t usually see this in a topper. I also think that that Odin2010’s top “soft” layer has a very wide range though, even for Dunlop, but the chances are that it’s just a guess on the part of the supplier to cover a wider range of possible firmness levels and isn’t the variance of any particular layer. It would be hard to imagine a supplier selling a Dunlop layer that was 27 ILD in a large part of the surface as being “soft” for most people.
I would also suggest that as soon as you label a specific design as being “better” than another either in terms of the type of material or in terms of layer thickness (rather than simply different) or turn preferences into “better or worse” suggestions … then those that take this to heart may quickly discover that there is no formula that can be more predictive than someone’s personal experience. In many cases they will start to focus more on the specs of a mattress than on their own personal experience. Everything depends on how all the layers interact with each individual person and body type.
Having two 3" Talalay layers for example is also a way to increase the compression modulus of the two base layers compared to a single 6" layer which in some cases can result in a higher compression modulus for the 6" combination than a single Dunlop layer with a single ILD. Different layering combinations changes compression modulus as well as the ILD at certain compression percentages in other words. Besides compression modulus … the response curve of Dunlop and Talalay are also different and Talalay has more initial resistance because of it’s thicker cell walls but then becomes firmer more gradually once the cell walls begin to deform so a lot depends on how much of a layer is compressed and where in the compression range it is. This can become so technical that it’s usually “best” to let personal testing and experience or the knowledge and experience of a retailer or manufacturer “cut through” all the technical stuff that can often lead to overanalysis and information overload. As soon as someone starts to question whether a 2" or 3" comfort layer is best for example without taking into account all the other factors involved there are so many “it depends on” in any answer that it becomes impossible to really know for certain with all the other interacting influences and can create a perception and analytical problem that can’t be solved by anything but personal experience.
Encouraging people to follow a formula can often be counterproductive because it becomes too easy to use theory rather than personal experience or the guidance and experience of a manufacturer with thousands of customers (and even then they can only go by averages and there isn’t any certainty that any design will match a specific person).
Post #26 here and post #2 here can give some idea of the complexities involved in using a formula or math rather than someone’s personal experience. “Theory at a distance” can be useful as a starting point or for gaining some insights into how layers interact with each other in many different ways but IMO it’s the least effective way to choose a mattress design (personal experience is the most effective followed by the help and guidance of a manufacturer who knows more than anyone about how their specific mattresses interact with different body types and sleeping styles … at least based on “averages”). In my experience … focusing on design or comfort specs (ILD, layer thickness etc) can often be counterproductive without specific reference points of someone’s personal experience.
Don’t forget … that in most cases on a forum you don’t hear from 90% or so of people where a “standard” layering design works very well and their first choice is their best one.
Phoenix