I am still getting lower back-aches from my latex bed after many months. The only thing that I can think of at this point is that maybe I don’t like the “point elasticity” of a latex bed after all. I think it may allow my hips to sink / rotate too much and arches my lower back. (While sleeping on my back)
What I have right now is 2" medium talalay latex over a 6" dunlop core. I never figured out what the actual firmness of this core was, as the seller said it was 31-35-31 zoned, yet the mattress has a label that says medium.
In any case, I was thinking that to “replicate” the non-point-elasticity of a regular spring mattress bed, maybe I should do something like put a firm layer on top?
Also, this bed developed a sag / soft spot where I sleep after only a few weeks. So I am not that impressed with the durability of latex. Hopefully it is only in the top layer and thus is cheaper to replace.
Point elasticity is the ability of a material to contour and shape itself to the contours and shape of the body more exactly when you lie on it and I’m not sure how it could be related to your comments which would seem to me to be more closely connected to the firmness of your layers or the design of your mattress and how well it “matches” your specific body type or sleeping positions in terms of PPP.
If I remember correctly you purchased your core from Arizona Premium and they are very knowledgeable and provide accurate information about their products so if they told you that it was 31-35-31 then I would consider that to be reliable information.
All materials will soften slightly over the initial weeks of use and this may be more noticeable for some people that are more sensitive than others so any softening you are experiencing may be in a “normal” range but of course there is always a small possibility that a material is defective and if this is the case I would talk with Arizona Premium. If you take each layer and put it on the floor you can measure the depth of any sagging by putting a straight edge or a string across the surface of the layer.
Maybe it is just a firmness issue, but I think the point elasticity is the major difference in feel btw a latex and spring bed.
Hypothetically, on a latex bed, my butt cheeks can sink down while the foam can still press up against the small of my lower back, causing an arch. Whereas on a spring mattress, if the butt part sags down, the lower back part sags down too, and thus doesn’t create as much of an arch.
I think I understand what you are trying to get at but I also think it’s an oversimplification of more complex factors that doesn’t take into account the many other specifications of the layers and components that interact with point elasticity and can affect the outcome you are describing including the many variations of latex and springs that are very different from each other, layer or component firmness, layer or component thickness, compression modulus/spring rate, resilience/hysteresis, the compression curve of different materials and components or combinations of materials and components, and the position of the material or component in the mattress (springs are usually used as support components and usually have other materials over them that can play a significant role in what you are describing while latex can be used in both comfort and support layers). In other words if you were somehow able to change only the point elasticity of the layers but everything else stayed the same then it’s not likely that this would resolve the issue by itself.
If you are comparing latex support cores with innerspring support cores (regardless of the materials above them) then there is more information in post #28 here that compares them but this is only generic because it doesn’t take into account the many variations of each that can have a very different feel and response and can be very different from each other.