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non-memory foam - foam mattress 13 Aug 2012 18:38 #1

Hi there, after my quest for a memory foam mattress for my back I've decided that perhaps just regular foam is the way to go. Does anyone know where one can buy just a foam mattress (no memory foam), and perhaps egg crate toppers if it is too hard?

thank you

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Re: non-memory foam - foam mattress 13 Aug 2012 20:07 #2

Hi maverick3934,

Assuming you mean "all polyfoam" and not "latex foam" or an "innerspring with foam" ... did you make it to DixieFoamBeds? They sell some good quality all polyfoam mattresses (and latex as well).

Phoenix
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Re: non-memory foam - foam mattress 13 Aug 2012 20:25 #3

I'm actually headed there tomorrow. Didn't know they make just polyfoam beds. That's good to know. I spoke to the guy on the phone, seemed very nice. However they didn't tell me where they get their foam from, but they seem the best place in the NYC area.

It's really interested when you start learning about foam - for instance correctly me if I'm wrong but the density of the foam makes no difference on softness nor support. Memory foam or just eggcrate foam could have the same pressure relief except memory foam tends to get softer as it warms up - much more than just regular foam...

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Re: non-memory foam - foam mattress 13 Aug 2012 23:32 #4

Hi maverick3934,

It's really interested when you start learning about foam - for instance correctly me if I'm wrong but the density of the foam makes no difference on softness nor support.


This is partly right. Density is mostly independent of the softness or firmness of a foam material (both low and high densities can be made in a full range of firmness and softness levels) although they are very loosely related (in the same "variety" of foam ... then much firmer is often a little higher density than much softer but not always). Density though is the single biggest factor in the quality and durability of polyfoam and memory foam.

Density is also related to compression modulus which is the rate that a foam gets firmer with deeper compression. Higher density foams tend to have a higher compression modulus (also called sag factor or support factor) although this too is not a "rule". The highest quality of polyfoam which is called HR foam has to have a compression modulus of 2.4 or higher (the ratio between the 65% compression weight and the 25% compression weight) to qualify as HR foam. When a foam has a higher compression modulus ... then even if it is softer than another foam with surface compression it will get firmer faster and can be more supportive than firmer foam with a lower compression modulus. Compression modulus is also a key part of the comfort of a foam as well because in combination with ILD (AKA IFD) it is part of what determines the depth of the cradle which is what redistributes weight over a larger surface area and relieves pressure.

Memory foam or just eggcrate foam could have the same pressure relief except memory foam tends to get softer as it warms up - much more than just regular foam...


Pressure relief is a very complex subject but in it's simplest terms it involves spreading body weight over a larger surface area so that the pressure on any particular part of the body is lower than the pressure inside the capillaries so the blood continues to flow. There's a very detailed and technical discussion of pressure relief in post #2 here .

As it relates to a material though ... pressure relief (and the corresponding sensation of softness) is connected to ILD/IFD, Compression modulus, and Point elasticity (where memory foam and latex excel and which determines how exactly a material can mirror a certain shape) which along with the thickness of each layer (which is independent of the properties of the material itself) controls how large a surface area is bearing weight and the distribution of the weight. Some types of zoning can also even out pressure by allowing more sinking in of some areas which allows the more recessed areas of the body to bear more weight.

In the case of memory foam it can be even more complex because it's softness is also affected by temperature, humidity, and the length of time it is continuously compressed so how soft it feels can also depend on the temperature sensitivity of the memory foam and can vary with your environment and circumstances or by how quickly a particular memory foam becomes softer with body heat.

Pressure relief also needs to be balanced with support and alignment because you could use a very thick slab of low ILD and support factor foam to do a great job relieving pressure but the heavier parts would sink in so far that the spine and/or joints would be twisted, bent, or flexed outside of their neutral range this would lead to the pain that goes with misalignment of the spine or joints.

The benefit of convoluted foam is first that it is less costly (you can use one layer of foam to make two convoluted layers that together are slightly thicker than the original layer) but it also alters the feel and performance of the foam. The shape and depth of the convolutions would mean that the upper surface of the foam was softer (less material) and as you sank in more into the thicker parts of the convolutions it would become firmer faster and then as you sank into the non convoluted part of the layer it would become firmer faster yet. In other words ... it simulates a higher compression modulus which means that it can be softer on top of the layer and firmer in the deeper parts of the layer. The tradeoff is durability compared to a solid layer of the same type, density, and firmness level of the foam although this wouldn't be a significant issue with more durable types of foam such as latex. This is a common part of mattress manufacturing in Europe where you often see special fabrication of various layers with surface modifications and various shapes and cutouts and convolutions to modify the feel and response of the foams used. It's also becoming more common in North America.

As you can see this is all quite complex but again the three specifications of a foam material that control most of the pressure relief (along with layer thickness) are ILD/IFD, compression modulus, and point elasticity (and temperature sensitivity with memory foam) which together with the thickness of the softer layers create the pressure relieving "cradle" and needs to be balanced against it's "opposite" which is support and alignment.

Phoenix
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Last edit: by phoenix.

Re: non-memory foam - foam mattress 07 Mar 2013 04:22 #5

Hi

I read this thread about foam mattress and see DixieFoamBed as a recommended company... I check their site and see that foam mattress are a lot less expensive. I'm particularly interested in non memory foam and I would like firm.. I returned my PLB Nature and because i did not love it I 'm wondering if spending all that extra money on foam is worth it if the latex is something that i as an individual cant appreciate. or, is it that i did not find the right latex and when i do it would blow the foam out of the sky?

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Re: non-memory foam - foam mattress 07 Mar 2013 06:04 #6

Hi aron82e,

I 'm wondering if spending all that extra money on foam is worth it if the latex is something that i as an individual cant appreciate. or, is it that i did not find the right latex and when i do it would blow the foam out of the sky?


There are 3 different types of "foam" (latex foam, memory foam, polyfoam) so it would depend on which type of foam you are talking about. Polyfoam is less costly than latex so you would actually be saving money if you used it vs latex. If you prefer polyfoam over latex or even if you can t tell the difference you are looking at high quality polyfoam, then it would seem to me to be a reasonable "value tradeoff" if it provided you with good PPP (Pressure relief, Posture and alignment, and Personal preferences)

Only you can really answer how you feel about latex or any other material. Each person has different preferences and the choice between latex and polyfoam and memory foam and different budgets is part of each person's individual value equation. There are many different types of mattresses in every category including latex so its quite possible that there are some you like and some you don't and each could have a different feel and performance. There are also many mattresses with latex over various different types of support layers (innersprings, polyfoam, latex) that would all feel different as well. There are also people who don't like latex in any version though ... just like any material ... and only you can decide if you are one of these or whether any material is "worth the money" to you.

I would focus on working with good local retailers or manufacturers that have good value mattresses (like Dixie foam) and then test different types of materials (including other types of latex mattresses) to see which you prefer.

Phoenix
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