Putting the layers together - overview

Discussions General Mattresses Questions
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An Introduction to Support and Comfort Layers

We have talked in previous sections about the role of the support and comfort layers and the different materials that can be used in each. In this section, we will talk about the 3 main ways of putting them together and about the remaining layers that will not only complete your mattress but can have a significant effect on how it performs and feels.

Mattress construction and layers that affect mattress performance and feel.

Differential Construction

This method uses thicker/softer comfort layers over firmer support layers. It is called “differential” because there is usually a big difference between the softness of the comfort layers and the firmness of the support layers. There is also a clear “split” between the roles of each layer as the comfort layers provide almost all of the pressure relief and supports the lumbar area and the support layer is focused on preventing the heavier parts of you from sinking in too far. While there may be a middle layer in this construction, it will be closer to the bottom layer in firmness as this construction is basically softer over firmer.

The main benefit of this construction is that it is easier to “get right”. Because the comfort layers are doing most of the work in filling in and supporting the “gaps” in the body, it is generally best to limit your comfort layer choices to materials that are more resilient to support the lumbar area and that also have the ability to shape themselves to the contour of your profile. Both of these qualities are important in the comfort layer of this type of construction. Because the support layers do not need to “help” the comfort layers with pressure relief, their ability to conform to your body profile is far less important and your choices in support layers are larger as almost any firm support layer is suitable for this construction.

A soft comfort layer over a firm or even extra firm support layer would be an example of this.

Read more about Differential Construction

Progressive Construction

In a progressive construction, the upper comfort layers are generally thinner and/or very soft and need to “borrow” from the support layers beneath to form a cradle and relieve pressure. These mattresses usually have several layers that become “progressively” firmer as you sink in deeper, and the difference between adjacent layers is smaller than with a differential construction. The layer below the comfort layer plays a dual role by helping the comfort layer with pressure relief/lumbar support and helping the bottom layer with spinal alignment. This can be done with either a middle transition layer or with the use of a support layer material which is softer and more conforming on the top and becomes firmer more quickly with deeper compression.

This method can be more difficult to get right but the results can be more accurate and individualized than a differential construction. Because the support layers are helping with pressure relief and lumbar support, any pressure-relieving comfort material can be used including those that are less resilient such as memory foam or natural fibers. The choice of support layers however becomes more restricted since they require more specialized abilities beyond simple “firmness” such as the ability to be softer and conforming on top (with initial compression) and firmer underneath (with deeper compression).

A softer/thinner comfort layer over a medium middle layer and a firm bottom layer would be an example of this construction.

Read more about Progressive Construction

Zoning

The body has 3 main areas where weight and the thickness of the profile can be very different. These are the pelvic or hip area which is often wider, especially in women, and almost always the heaviest area of the body; the lumbar area which is much thinner, lighter, and more recessed in most people; and the shoulder upper chest area which is lighter than the hips but often wider and larger, especially in men. The widely different needs of these three areas in more difficult circumstances such as unusual weight or body profiles are sometimes outside of the range of even the best materials using either differential or progressive constructions. In these cases zoning can be the answer to a perfect mattress.

Zoning uses different zones of material or firmness in different areas of a comfort or support layer such as a firmer zone under the hips to keep them from sinking down too far. It can also be quite complex and in many cases poorly understood by those who sell mattresses. Incorrect zoning schemes can do much more harm than good so it is usually a good idea to only use it when circumstances warrant. Different zoning schemes may use any type of comfort layers over any type of support layer depending on the type of zoning that is being used and the individual circumstances or difficulties that need to be addressed.

The most effective zoning schemes usually have either 2 or 3 zones in different "arrangements. More than this is of questionable benefit and often used to justify a more expensive mattress that may not even be an appropriate choice.

Read more about Zoning

Other layers that are part of some or all mattresses and that are used to complete your mattress.

  1. Quilting layer: Commonly used as a layer above the comfort layer. Usually made from foam or fibers and forms a separate but interconnected part of the comfort layer. It can affect breathability, temperature regulation, and pressure relief as well as overall feel and can also be used for fine-tuning.
  2. Ticking: This is the fabric that surrounds the mattress and it too can affect breathability, temperature regulation, and pressure relief as well as have a significant effect on the overall feel of the mattress.
  3. Fire Barrier: This is used to prevent a mattress from bursting into flame and preventing “flashover” from either a smoldering heat source or with an open flame. The “open flame” regulation that all mattresses now need to comply with was added in 2007 to the first “smoldering heat source” regulation that was already in effect.
  4. Insulator: This is a layer which is used over an innerspring to prevent the layers above it from shifting into the innerspring and is also used to alter the feel or response of the innerspring itself.

Each of these different methods of construction and additional layers are discussed in more detail in the pages of this section.

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how do you reinforce the edge of a latex mattress-we are heavy?

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Hi Suzanne,

Because latex is so durable and also point elastic (conforms to the shape of the weight on top of it without having a significant effect on the area beside it) and because of its high compression modulus (the rate at which a material gets firmer with deeper compression) … for most people it doesn’t normally require edge reinforcement for sleeping even for heavy people as long as the support layers are firm enough and the comfort layers aren’t too thick and/or soft for the person sleeping on the mattress.

Because of its point elasticity though … those who sit on the very outside edge a lot (instead of sitting with your body weight more into the middle of the mattress) or who sleep with more concentrated weight on the outside few inches of their mattress may find themselves sinking down more than they like even though this isn’t normally an issue when sleeping on the mattress. For those who prefer a firmer edge then you may occasionally find a latex mattresses that use what’s called a “racetrack” perimeter where the outer few inches of the latex support core is replaced with a firmer foam that is glued to the core. Unfortunately, most of the time this firmer foam is a much less durable (but firmer) polyfoam which will soften and break down sooner than the latex and what starts out as a positive can become a negative over time (depending on the density of the polyfoam this can sometimes be a fairly short time). Because of this it would be much better to use firmer latex in those cases where perimeter support is preferred rather than less durable polyfoam but this is an uncommon construction for latex.

In some cases edge support for a latex core that uses polyfoam can be a way to reduce material costs (polyfoam costs less than latex) that is promoted as a “benefit” … even though in durability terms its not. Having said this it may still be worth the tradeoff for some people whose testing or circumstances indicate they would either benefit from a firmer edge or who sit on the very edge of their mattress and need a firmer edge and if this is the case I would make sure that the edge support uses high quality materials (I would suggest a minimum of 1.8 lb polyfoam or higher) so that the edge support is as durable as possible and won’t become an issue over longer periods of time.

In most cases though … a mattress that has a support layer that is firm enough relative to body weight of the person sleeping on the mattress will be fine for most people.

Phoenix

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Thank you so much=Would a perimeter 3 inches high by 4 inches wid-50 lld be appropriate? this would be over a 6inch 36lld base and the center filled with softer latex layers. what about shifting-this will be in a split king adjustable frame. S-Cape I think. Suzanne

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Hi Suzanne,

The perimeter size and ILD would be fine (50 ILD is very firm) and you could certainly test it by sitting on it to make sure it worked well for you. I would ask though what type of foam was being used. If it was polyfoam (which is likely but not as good an idea for the long term) then I would want to know what the density was. I would not even consider anything lower than 1.8 lb density and higher would be much better (more durable). Best of all of course for durability would be latex.

Normally the firmer border foam is underneath the top layers (rather than part of the top layers) and around all or part of the support core of the mattress. I wouldn’t want it to be part of the comfort layer itself.

As long as it is well glued it shouldn’t come apart or shift with long term use on the adjustable bed but I still wouldn’t be completely comfortable with its long term performance if it was polyfoam.

Phoenix

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Thanks again for an interesting and informative site. With this said, it seems like there are some missing pieces to how a mattress feels. Although I would like to use latex for the “natural” aspect and eliminating off gassing odors, I felt similar issues with the severe bouncing and jiggling that one of the most recent posters had problems with. After spending an entire day trying mattresses at 8 different stores, I found the differences from mattress to another is enormous, even if it is supposedly the same 100% latex makeup.

The construction around the sides or the ticking seems to actually make a huge difference in the way these mattresses feel contrary to what you have been recently discussing. An extreme example of this was from a company called Green Mattress shown at the Natural Mattress company in Denver, but it is also extreme in their price. The more elaborate, and expensive mattresses, seem to control the “wavy” feel much better with the way they wrap up their mattresses. Yet at the same time it is not compressing it, because the conforming, pressure relief seemed to be better too.

Also the memory foam feel is becoming much more interesting to me as the most supportive, motion isolating, and pressure reducing. However there is still concern with the smell or potential harm from the off-gassing. Can you bring up a separate discussion, similar to this forum on memory foam? Also, I have noticed that there is not much discussion on Tempur-pedic on this site, yet it seems to be an interesting alternative. Especially with their ES layer on the cloud series, as this is the only style that gives a nice feel when you lay down and as it molds. The other memory foam styles just seem too hard at first.

If someone could point me to a latex mattress that wouldn’t be so “bouncy” and motion consistent, more conforming with pressure relief, and natural then I could end this long search. Oh, and I am also really concerned with heat too. Otherwise I am really tempted to go the direction of the Tempur-pedic, even with the worry of the off-gassing. Are there any good links for information on the health issues from the chemical problems. I have seen you mention you actually had personal experience from the gasses, can you elaborate?

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all the layers will be 100% natural latex. I am making this. what do I glue it with? Thank You, Suaanne

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Hi needsleep,

What you are describing is part of the “feel” of latex. Some people call it "bouncy, some people call it “springy”, some people call it “jiggly” and sometimes it seems there are as many different descriptions as there are people. The same is true for memory foam, innersprings and almost every material. This is why the first “step” in finding a mattress is to determine the initial and general feeling of different materials and layerings. These different “feels” are the reason why some people love a materials and some people don’t. How a mattress “interacts” with different people or couples and the amazingly wide variety of different perceptions between different people to describe the same thing is also an important part of choosing a “perfect” mattress. I am always amazed how different people or couples who test the same mattress will describe it in so many different (and in many cases opposing) ways. Some will call it “too firm”, some “too soft”, some “perfect”, some “too jiggly” some “too dead” and many other descriptions and yet they are all talking about the same mattress and in many cases the same “feel”. This is why personal testing is so important.

There is also a difference in feel between different types of latex such as Talalay and Dunlop and even different “feels” between different combinations of materials or layering patterns. All of this can create strong feelings in people about which one is “best” when in reality it is simply a matter of preference.

There are certainly people who don’t like the feel of latex in any of the combinations they have tried and I think that the most common reasons for this are first of all the feel itself (don’t forget it is a rubber foam with the overall characteristics of rubber) and secondly that it is often firmer than they are used to (most manufacturers use very soft polyfoam on the very top of their mattresses just because people are used to and often like the feel of ultra soft foam on the very top of their mattress … at least in the showroom).

I’m guessing that the mattress you are referring to at the Natural Sleep Store in Denver was the GreenSleep and it makes a very good example of exactly what we are talking about. It uses Dunlop latex (a denser and firmer form of latex which is not as lively) and has a very thick wool tick. It is a very high quality latex mattress but is significantly overpriced IMO compared to other mattresses that use similar materials. It also has an adjustable dowel system underneath it which can also change the feel of the mattress (similar to other adjustable slat foundations that are used under a thinner mattress). For some people … Dunlop latex is just too firm even in its softest versions as a comfort layer and they may choose softer Talalay or something else. They may even come to believe that “latex is too firm” rather than “latex is too jiggly”. Having said that … if it is the “perfect” mattress for someone in terms of pressure relief, alignment, and feel, then it would certainly be a good investment in better sleep although I personally would tend towards a lower cost option which used the same or similar layering and materials for half the price even if the “feel” wasn’t exactly the same (it would be “similar”).

In addition to this … there is a huge range of different feels that can be created by varying the ILD’s of the layering in a mattress and through various combinations of ticking, quilting, and construction methods such as tufting (as you mentioned) This last “piece” in particular has been the topic of many discussions on the forum and is the subject of several pages on the site as well. Just to further confuse the issue … many manufacturers will call a mattress a “latex” mattress when in fact it often has only a very thin layer of latex in it and what people are feeling is another material completely. This is the reason that knowing what is in your mattress is so important. If any of the 8 stores you visited for example were chain stores or the mattresses you tried were national brands … then it is unlikely that what you were lying on was really “all latex” no matter what you were told. Many places will use the “value recognition” of the word “latex” to mislead people into thinking that what they are lying on is latex when it is “partly latex” at best. Words like “organic” and “100% natural” are often also signs that the prices for a mattress are higher than mattresses that use the same materials but don’t focus so much on the “natural” or “organic” part of the market as they do the “comfort” part of the market. It is well known that those who are looking for more “natural” or “green” or “organic” sleeping options will pay more for a mattress at a store that specializes in “natural” even if what they are buying uses exactly the same materials as another mattress being sold by an outlet or manufacturer who is focused more on other aspects of a mattress and the “natural” part is secondary.

For those who just don’t like the feel of latex by itself but still want some of its other benefits … then a latex comfort layer over an innerspring or a combination of latex with memory foam in the comfort layer is often the “answer” they are looking for. This last one for example is one of my personal “alternative” favorites in terms of feel but even here there can be a wide variety of different “feels” and what one person likes can often be the worst possible choice for another.

There are quite a few pages on the site itself about memory foam (which is actually the least supportive foam of all but very pressure relieving) including this one. If you search the main site for memory foam you will find 34 pages which mention it … some of them in quite some detail. If you do a search on the forum for memory foam there are 533 results. A forum search for Tempurpedic will bring up 131 results. Some of the memory foam and Tempurpedic theads have some very detailed and even technical information in them including many examples of my thoughts on Tempurpedic and its “value” in general. Some examples among many others are here and here and here. There is also a lot of memory foam information inside the longest thread in the forum which is the iComfort thread here.

In terms of memory foam offgassing … there is a huge amount of information about this … much of which is conflicting. Part of this is because there is such a wide variety of different types of memory foam and different chemicals and variations in the methods used to make it. My own personal experience is here. A forum search for “offgassing” will bring up 13 hits. Some of the “offgassing” symptoms that have been reported and discussed on many places around the web are here and here. These issues are part of the reason why I normally recommend only using memory foam which has been tested and certified by a reputable agency and are part of the reasons for the “guidelines” I normally recommend (such as in post #2 here) when people are considering including memory foam in their mattress.

Hopefully I have dealt with some of the rather “complex” issues and questions you have raised and rather than start a new thread on “memory foam” when there are already so many … I’d certainly be happy to answer any more specific questions you may have or “point you” to any other information that may be important to you.

Phoenix

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Hi Suzanne,

Most (or at least many) places that sell natural latex will also sell water based latex glue which is very strong and doesn’t have the offgassing issues of other types of glue. Local foam shops will also normally carry it as will many local manufacturers.

You can also choose to add “edge support” on either just the sides or all the way around. Normally it is around the lower layers rather than the upper layers (see the iComfort edge support example here)

If you are ordering your latex in separate “uncovered” layers with an eye to making your own mattress or even fabricating your own layers (cutting a layer and then gluing a racetrack around it or on the sides of it) … I would also make sure that the outlet you are ordering from is reputable as there are several that will sell you something which is not labelled correctly and what you receive may not be what you think you are ordering.

I’d love to hear about your “design” and how it goes.

Phoenix

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Thanks again for the enormous amount of time and research you have put in to the mattress dilemma. Hopefully through the trial and errors I will find one that fits just right.

Interesting point that you say memory foam is one of the least supportive - I thought this is why they use the material in medical scenarios, and if it fills in all around you it seems like it would support the best. I have a lot more reading to do.

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Hi needsleep,

The ability to form a cradle that takes on the shape of the body and spreads the pressure over a larger body surface area is why memory foam is so pressure relieving and is used in the upper layers of a mattress (including some medical uses where it and other methods and materials are used to relieve pressure points which cause pressure sores). It is never used as the support (lower) layers of a mattress though because it allows the heavier parts to sink in more deeply and doesn’t hold them up as well as other foams. The “typical” memory foam mattress (including Tempurpedic) has several inches of memory foam in the upper layers and then a more supportive foam such as polyfoam or latex underneath it to prevent the heavier pelvic area from sinking in too far and causing lower back pain over the course of the night. Memory foam “allows” sinking in to create pressure relief while more supportive and firmer foams that are used underneath it “stop” the heavier parts from sinking in to create spinal alignment.

All memory foam is considered “soft” although it may not feel soft when it is colder or when it is compressed rapidly (like water is soft if you sink into it slowly but firm if you “slap” it). Memory foam may be considered more or less “supportive” when a particular formulation (and there are hundreds if not thousands) is compared to other memory foam formulations as there are “more or less” supportive versions … but none of them are suitable for use as the support layer of a mattress. Over time and with the changing temperatures of the sleeping environment, they would all allow the heavier parts of a body to sink in further than would be desirable for best alignment if they were used as a support system and they all need the “help” of other more supportive options (polyfoam, latex, or innersprings) underneath them.

There are many “memory foam” myths presented as “fact” that abound all over the internet :slight_smile:

Phoenix