Mattress Forum

The chart was very interesting and I spent some time there to make sure I had a logical explanation for the different effects. One of the most interesting things is that ILD is only about the upper 25% of a layer. If you compress a HR foam that is softer in the upper 25% to 65% then it could be much firmer than a lower quality foam which starts off (first 25%) much firmer but doesn't have as much difference when it is compressed and so is softer with deeper compression. This is why compression modulus (sag factor, comfort factor etc) is so important as it is rare that someone actually sinks into a layer exactly 25%.

In other words ... the response curve of higher quality HR foam can start off softer but "curve upwards" faster and end up firmer in deeper parts of the layer. If latex was a polyfoam, it would be considered an HR foam. Different formulations of latex will also affect it's qualities although they would all be considered HR.

Phoenix

I'm going to spend a bit of time looking at all the things you tried before I give you any beginning ideas.

If you're game for this I am. Should we start a new thread to save confusion in this one or just leave it here?

Phoenix

Yes, should start a new thread if Steve is getting confused.  But somehow I think we are both in the same boat..

And yes ... any videos or pictures that may help would certainly be welcome.

Phoenix

Not to worry, I am usually confused. 

Leo I've been reading thru your thread and yes it sounds like we are in the same boat. But separate threads still make sense. Best of luck to you...
 

Steve

Yes it certainly is possible however it is likely more a matter of preferred feel than the innersprings themselves as the same "issues" and "tradeoffs" of support and comfort apply with them as well. They are just a different approach.

More later ... but well before your guests leave :)

Phoenix

If this is too long the short version is ... I believe any commonly used "layers" in a mattress can provide proper support and comfort but they do it with a different "feel" and in different ways. Incorrect layering or construction for an individual may result in problems with a certain material but it is not the material itself which is the culprit but incorrect construction (for the individual) or "incorrect" use of that material in a certain construction. Sometimes this incorrect use is so common that people believe that certain materials are not appropriate at all. Because of the different feels between different constructions as well, many people will have clear preferences for one "system" over another. So latex over innersprings in some cases may make it easier to get a correct support/comfort balance for some (other combinations with different materials may be more difficult to get right for them) and it may also create a feel (more bouncy and lively) that is preferred by some. So part of this is difficulty, part of this is preference.

Now the longer version for those who want to read more. This was also the subject of several long and interesting conversations with various mattress manufacturers....

Most springs have more resiliency so are stronger in their pushback than latex foams. For example if you were to drop a ball on a spring (assuming you got it dead on) it would bounce back higher than a latex foam. Different springs are also designed to have a different response curve in the same way that different kinds of latex or poly have different response curves. Many springs (like offset coils) are designed to compress more easily under lighter load (the "hinge" flexes) and then offer more resistance past a certain point (from the coiled spring) to keep you in alignment. This transition from softer to firmer can be more sudden than foam. Stearns and foster also has a coil in coil system which is another way of doing the same thing. The thinner taller coil flexes with less resistance at first but when you sink in deep enough, the thicker coil comes into play to keep you from sinking in too far. Even bonnell springs have a thinner part in the middle which flexes under lighter load and then when it's compressed past a certain point the coil becomes stiffer. Latex and other materials also tend to compress more easily at first and then offer increasing resistance with depth but they tend to do this more gradually and progressively. Materials or innersprings that increase more rapidly or more "suddenly" than others (have a different response curve) create a different feel but they are also easier to work with since the point they "bottom out" comes inside a narrower range and is easier to predict with differing body weights.

In terms of coils, probably the closest overall to latex would be pocket or marshall coils which flex more individually in the same way that latex can flex in a very small area without affecting the surrounding material as much. Marshall coil innersprings in other words have more "point elasticity" than other types of innerspring but still much less than latex. There are also varieties of pocket coils (different gauges, shapes, and number of turns) which have different response curves than others. The idea with all of this, whether you are using foam or innersprings, is to allow enough sinking in to distribute pressure and create alignment without allowing so much that you begin to hammock and go out of alignment.

The other part of this support "equation" is point elasticity and this is where there is a real difference between latex and innersprings including pocket coils to a slightly lesser degree. Most people tend to sink in more in their hips. They also have a more recessed area in the small of the back (back sleeping) or the waist (side sleeping). These two areas are so close together that without point elasticity the hips pushing down would also compress the material in the lumbar/waist area and there would be less pushback or resiliency where it was needed to support the lower spine and keep it in alignment (straight on the side and "s" shaped on the back). Any coil or firm material can be great at the kind of support that "keeps the hips up" ... but most are not so great at letting the hips sink in and keeping the lumbar/waist beside it up. This is where zoning schemes, marshall coils, and latex and even HR poly come into into play. They can be compressed in one place and yet still push back and support in an area that is very close by. This is also the reason that many people misunderstand the whole idea of support. The important question here is "how much and where?"

In terms of innersprings and even foams, there are two basic zoning methods which are used to allow or prevent sinking in and to support the lumbar/waist.

The first one and more common is to put stiffer coils or material under the hips to prevent them from sinking in too far. When this method is used, you also need something which will push back and support the nearby lumbar. A material like latex or HR poly over an innerspring like this can be used. A marshall coil can also be used to push back (or increase the pushback) from a deeper part of the mattress but then this pushback has to go through the right parts of the the upper layers as well. This type of support would be a little "weaker" since the hips have been stopped and the coils or the upper layers that are pushing back are less compressed and doing so more weakly. This kind of "relatively weak" pushback feels good for most people as long as there is not too much pressure on the hips (the "bottom point" didn't happen too suddenly).

The second method results in "firmer" support under the lumbar. In this method the area under the hips (and shoulders) is made softer and the hips (and shoulders) are allowed to sink more. The area under the lumbar is made firmer so the lumbar sinks down onto the firmer area and becomes more load bearing. The body's own weight is creating the "support". Laying with a suspended piece of lumber across the small of your back and balancing there would be an extreme example of this. In a case like this there is not nearly as much need for the upper comfort layers or pocket coils underneath to "push back" since there is already weight on the lumbar and if they are too resilient in that area, the combination of their pushback and the fact that the lumbar is already bearing weight may make this pushback uncomfortable or even create pain. This type of zoning scheme is more suitable for lighter people, people with unusual weight distribution profiles (such as back sleepers with a lot of weight directly over the lumbar area), or people who are able to tolerate (or even need or enjoy) more "upwards" pressure on their lumbar without discomfort.

So too little pressure or pushback in the small of the back which allows it to sink or collapse out of alignment when relaxed (like laying on a floor) ... and too much pressure in the small of the back from load bearing and/or pushback can both create discomfort or lower back pain. The method of "keeping the hips up" and using resilient and "point elastic" materials (like latex or marshall coils) for lumbar support is more common because it results in less pressure on the lumbar which is more comfortable and tolerable for most people and body profiles. The second method of "allowing the hips to sink in" and firming up the lumbar support using body weight creates more pressure on the lumbar (especially for those that are heavier or have certain body/weight profiles) and can lead to discomfort or pain for some, especially if used in combination with certain resilient materials. For others though, especially those with lighter weight or unusual profiles, it may be preferable.

So to answer your question "would inner springs with latex over it be better for some?". My answer in terms of feel is yes. Some people may well prefer the more bouncy, lively nature of innersprings.

If they do like this feel then there is always a "perfect for them" inner spring and comfort layer combination that would provide "just the right amount" of comfort and "just the right amount" of support and "weight"  on the lumbar or other areas. This may be through layering, use of materials, or zoning. Like goldilocks ... their innerspring construction can result in "not too much" and "not too little" in all the right places.

Other people may prefer the more motion separating, less bouncy, and more cradle like "softly supportive" feel of a latex core. Here too proper construction, layering, and possibly zoning can result in "just the right amount" of comfort and "just the right amount" of  support or "weight" on the lumbar. Because latex is more "progressive" and has a wider zone of bottoming out than most springs, zoning is usually less necessary but it can be a little more difficult to "get it right" in some cases.

So in the end there isn't really a "right or wrong" material. There is "easier and more difficult" to work with and there are always many moving parts to take into account. Assuming though that someone is willing to go through the time and effort it sometimes takes to get to the perfect combination of comfort and support, then which material or method of support used is really a matter of the difference in feel and preference.

Phoenix

PS: This is why, when zoning is required at all beyond the natural zoning that is built in to certain materials, I like the 2 zone approach with softer (allowing sink in) in the shoulder area and firmer (holding up) in the hip area. This keeps the hips from sinking in so far that it produces too much pressure on the lumbar but allows the shoulders to sink in enough to relieve pressure there and also slightly firm up support for the lumbar beyond what material or layer resiliency alone would provide. My second favorite would be 3 zone with the hips firmer and using natural zoning and resiliency of materials and layers to provide support for the lumbar. My least favorite would be multiple zoning beyond 3 or "reversed zoning"  which I would only use in more extreme and unusual circumstances or with the use of low resiliency materials.

The above config actually felt ok for a few nights, at least until the cuddlebed hammocked. Altho my back and shoulders are both a little sore. I think tonite I will just remove the cuddlebed and try the mem foam over the mattress alone...

http://s1025.photobucket.com/albums/y311/st3v3k4hn/sleepez/