memory foam as i understand it is normally a comfort layer but can be a support layer if of reasonable size and density. So many companies now use a smallish (1 or 2 inch) layer below a similar polyfoam layer. Now here the polyfoam would be more supportive than the memory foam so what is the benefit to having the memory foam? just for marketing purposes. Further since memory foam is activated by body heat its effectiveness is again reduced. So multiple issues of when does a comfort layer become both comforting and supportive. compression modulus? but its hard enough to get basic specs from these companies let alone this sort of figure.
Hi heywannaplay,
I’m not quite sure if you’re asking a question or just making a statement, but I’ll comment upon a few of the things that you said in case it is helpful.
Memory foam is indeed most commonly used in the upper layers of a mattress, as a comfort layer or sometimes as a “transition” layer between the comfort layers and the support core. It would not be appropriate or suitable to be used as a support core, as memory foam is generally quite plush and does not provide prevention of “bottoming out”. And like polyfoam, the hardness of memory foam is not directly related to the density.
Memory foam provides a comfort, just like any other foam, and where it is placed within a mattress (upper or deeper comfort layers) would be the result of the level of comfort that the mattress designer was attempting to achieve.
The deeper a memory foam layer is placed within a mattress, the less susceptible it will be to the impact of body heat, which means that the viscous nature of the foam won’t tend to change as much as if the layer was on top of the mattress. I wouldn’t term this as having the “effectiveness reduced”, but instead as having the change in viscosity reduced, which may be the goal of the mattress designer by locating the layer deeper within the mattress. Without our crystal ball, we can not infer the reason for the design of the mattress, only the final result.
Comfort layers are generally meant to be just that – layers that provide comfort – and not as concerned with support. Latex does have a unique ability to be quite point elastic but then also “firm up” as weight is applied (can have a higher support factor or compression modulus). Some true high resilience polyfoams can also have such characteristics.
There is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel” that may be useful as well.
I’m not sure what “sort of figure” you’re attempting to acquire. All the information you need to know is in this article. While the specs that affect the quality and durability of the layers and components are important to know … when you are testing a mattress locally then disclosing “comfort specs”, such as ILD/IFD, isn’t really necessary or even an important part of transparency because with careful testing your body will tell you much more about whether any specific combination of layers or components or any specific mattress is a good “match” for you in terms of comfort, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences). Such information as this or the compression modulus of a specific foam layer (or even of a finished mattress, which is not something that is measured) would be completely meaningless and only add to the confusion for most consumers anyway.
Phoenix
well im basically wondering the point of memory foam as a second layer in a classic three layer configuration. Say 2 inch top HR polyfoam 3.5 pcf, 2 inch memory foam 3.5 pcf, 6 inch base layer 1.8 pcf.
The top polyfoam at 2 inches having less compression modulus than if it was say 4 inches on top of the base layer with no memory foam. So more comfort than support relatively speaking than if 4 inches. the 2 inches of memory foam is for what? its now more like a slow to respond polyfoam because there is no direct body heat. So how is 2 inches of hr polyfoam on top of 2 inches memory foam more sensible than 4 inches of hr ployfoam instead of using memory foam in the middle layer. Im wondering if this is done just so tempt buyers who like memory foam while saying its responsive because of the top polyfoam. Is there any benefit to using a memory foam in the middle rather than some other transitional layer.
Hi heywannaplay,
I thought I addressed your question in my previous reply, but I’ll expand a bit here. All of the layers of a mattress work together to achieve comfort, and the choice of thickness, type of foam, ILD, density, compression modulus and ordering are the result of the comfort that a mattress designer is attempting to achieve. If you’re attempting to figure on “why” a designer used a certain layer of foam in a certain position, you’d have to contact that designer personally. Otherwise, attempting to infer such things would be mostly a waste of time, and instead you’d want to focus upon the quality of materials and then test out the product to determine if it aligns with your own PPP.
A 2" versus the same 4" layer of the same polyfoam would have the same compression modulus rating. The 65% ILD / 25% IFD measurement used for this is taken usually from a 15" x 15" x 4" sample. A 2" slice from this piece of foam test would be represented as having the same support factor as a 1" or a 4" piece of the same foam. Perhaps you meant that 4" of polyfoam versus 2" of that polyfoam on top of 2" of memory foam (tested together as a unit) would firm up at a different rate, or have a different support factor, which of course it would.
There is no definition of “sensible” for a mattress design - it is simply a different design to achieve a different comfort.
I don’t believe that would be the case. It is a common arrangement to achieve a specific comfort. If a manufacturer was looking to place a “token” layer within a mattress, then generally it would be thinner and less expensive.
It achieves a specific comfort and feel, so the benefit would be how effectively that layer combines with other layers to achieve a specific desired comfort. It can provide a bit of “deadness” to a mattress and a bit of a dense feel, with a bit less viscosity change, depending upon all of the other materials used in the mattress.
While knowing the specs that can affect the quality and durability of the layers and components in a mattress is always important, unless you have a great deal of knowledge and experience with different types of mattress materials and components and their specs and different layering combinations and mattress designs and how they combine together and can translate them into your own “real life” experience that can be unique to you (which would generally be a very small percentage of people), I would tend to avoid using complex specifications to try and predict how a mattress will feel or perform for you. When you try and choose a mattress based on complex combinations of specs that you may not fully understand or only based on specs for single layers or components that may not be as relevant or meaningful as you believe it is then the most common outcome is “information overload” and “paralysis by analysis”. Even the best mattress designers in the industry are often surprised at what a mattress they design “should have felt like” based on the specs when they design it and what it “actually feels like” when they test out their new design. There is no formula that can predict with any certainty what type of layering you may do best with that can possibly be more accurate than your own personal experience., and there are many manufactures who have used comfort layer combinations like you are mentioning.
Phoenix