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Searched for: critical zone depth cradle
09 Sep 2014 16:02
  • phoenix
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Hi awoods,

I am already concerned that the comfort layers on that specific mattress are not thick enough for my husband's shoulder, so I'm very interested if Halifax resolved his issue. Hopefully he'll post an update.

While it may turn out to be true that you need a thicker comfort layer ... the "comfort zone" or what I have sometimes called the "critical zone" isn't the same thing as the thickness of the layers on top of the mattress and will have more to do with the relative firmness of the top few inches of your mattress combined (regardless of the thickness of any individual layers). There is more about this in post #4 here . If it did turn out that your shoulders don't sink in enough to provide good pressure relief then this would be a case where adding a topper can provide any "fine tuning" that would be necessary if you don't have any other "fine tuning options" such as a thicker top layer, a softer top layer, a different quilting pattern in the mattress cover, or other options such as a different pillow or a different mattress protector that can improve the pressure relief under the shoulders.

With pocket coils, there are 2 things that might not work so well for me. One is possible increased offgassing from the polyfoam surround and pocket coil glues, since I know I'm sensitive to offgassing. The other is the possible increase in dustmites due to the pocket fabric. Do you have opinions on either of these?

There is more about dust mites in post #2 here but in order for dust mites to multiply and thrive they need a source of food and a source of moisture. Their food comes primarily from skin flakes and a mattress protector (or in some cases a mattress encasement for those that are much more sensitive and/or have known dust mite allergies) would greatly reduce the amount of skin flakes that enter your mattress and "feed" the dust mites. The other is a source of water which they "drink" by absorbing moisture from the air or environment around them. Since coils are more breathable and have higher airflow than foam and ventilate well ... they would be less likely to retain the moisture levels that are needed by any dust mites in the mattress. Although it's true that pocket coils that have fabric pockets will have less ventilation than innersprings that don't use fabric pockets ... it's unlikely that ventilation would be an issue with any type of innerspring (see post #2 here ).

In terms VOC's and offgassing of the foam surround ... the large majority of people would be fine with polyfoam that was either made in North America and/or was CertiPur certified. For the very small minority that were more sensitive to any specific VOC's than CertiPur tests for (you can see the testing limits here*) because of unusual sensitivities such as MCS (multiple chemical sensitivities) or other health conditions ... then they would probably also be sensitive to polyfoam used in their furniture as well and may be better off to avoid polyfoam altogether.
ADMIN NOTE:*Always check CertiPur site for the latest guidelines available

And I will wait to ask Fox about the comfort layer thickness until after I do some further local testing of latex to find out if a thicker comfort layer feels better to us.

That's a good idea but again ... I would keep in mind that the "critical zone" and the depth of a pressure relieving cradle will also depend on the type, firmness, and thickness of the comfort layer along with the softness of the next few inches of materials or components underneath it. If a mattress you test has a thicker or softer comfort layer but uses firmer layers or components underneath it then it may not be a good reference point for comparison because it could still feel firmer to you than a mattress that uses a thinner comfort layer.

06 Sep 2013 19:49
  • phoenix
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Hi TweedSAFD,

The only question left unanswered that would help me decide is how thick of a comfort layer should I get. I am a 6'2" 230lb side sleeper with an athletic build with wide shoulders.

While it may not be the answer you may be hoping for ... the only "real" answer is "just enough" to relieve pressure in all your sleeping positions. The thickness of any specific layer that works best is always relative to the rest of the mattress design. All the layers of a mattress interact with and affect all the other layers so the actual thickness of any layer that is "ideal" would depend on the specifics of all the other layers in the mattress and how that specific combination interacts with your body type, sleeping positions, and preferences. Post #2 here has links to some of the articles that discuss some of the theory and concepts behind layer thickness and ILD for different designs and constructions and a forum search on " critical zone depth cradle " (you can just click this) will bring up more posts that discuss the relationship of the depth of cradle or what I call the "critical zone" to layer thickness and ILD but these are only generic concepts and only your own testing or sleeping experience can tell you whether a specific design provides the best possible balance between comfort/pressure relief and support/alignment. There is no "theory" or formula that can answer this for any specific person without specific reference points based on personal experience but the guidelines can provide a good starting point for those who want to become more involved with the specs of their mattress design.

Post #14 here also has some information about the potential benefits of thicker layers or mattresses for higher weights that may be useful.

In most cases though ... there are "many roads to Rome" (Rome being the mattress design that provides the ideal combination of pressure relief and alignment) and there are usually several different designs that can provide a similar outcome.

14 Aug 2013 17:30
  • phoenix
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Hi carmutt,

1. You mention that 2"-4" of comfort layer is recommended for side sleepers, but that it is a personal preference thing and one should try to get by with the smallest height in the comfort layer they can to attempt to ensure the bed is not "too soft" or causing potential alignment issues. When you state that, does it make a difference if there are 2"-4" on each side of the mattress? Could that much on both sides of the mattress potentially cause even more issues than on a single sided mattress?

Generally it would be in the 3" to 4" range but it's only a guideline and would also depend on the specific construction of the mattress and the layers below it. It would probably be more accurate to say that the typical depth of cradle or what I call the "critical zone" would be in this range regardless of the thickness of any specific layers. Guidelines can be useful as a starting point or to gain an understanding of concepts but not as a specific recommendation for any person.

If for example you have a 6" layer of Dunlop latex, the ILD is tested at 25% compression which is 1.5". If it is under another layer and was only compressed by an inch ... it would "act" softer than its ILD would indicate and the top 1" could be part of the "critical zone" or comfort layers even though it isn't a separate layer. If it was compressed by 2" it would "act" firmer from that point on and the top 2" would be part of the "critical zone" and from from that point onwards could be part of the support system. In other words all the layers compress at the same time and interact together and affect each other regardless of the thickness and softness of every individual layer..

If you put soft foam on both sides of a mattress then the foam underneath would have an affect on the support/alignment of the mattress yes which is why two sided mattresses are more limited in how they can be designed (it's usually a good idea to limit softer comfort layers to around 3" or less in a two sided mattress and they would typically have a firm middle support component and then softer foam on each side rather than a more progressively firm design that is possible with a one sided mattress).

2. Overall, the 2"-4" of comfort layer needs to be of HR foam (2.5 lbs), 1.8 density or higher polyfoam, latex, or microcoils to really stand up to wear. While this is always the weak link in the bed, it is worse with lower density foams as foam will break down and cause softening of the bed even further, which may cause it to be "too soft" or "over the edge" soft which can also lead to alignment issues.

Yes this is correct. Softer foams of any kind will be less durable than firmer foams and thicker layers of less durable foams will have more softening than thinner layers mixed in with higher quality foams. 1.8 polyfoam in thicker layers on a one sided mattress could still have some softening under the heavier areas of the body. The softening under specific parts of the body (particularly the pelvis and to a lesser degree theshoulders) is the biggest issue. If a less durable soft layer is thinner then foam softening can lead to "going through" the layer more easily with the hips or shoulders and feeling more of the firmness of the layers below it and cause pressure issues even though the support layers are still "stopping" that part of the body and there are no alignment issues. If less durable soft foams are thicker ... then even with foam softening under the pelvis or hips they may still be thick enough to isolate you from the firmness of the support layers but your pelvis or hips will "travel" deeper into the mattress leading to pelvic tilt and alignment issues (and a sore back). In other words ... foam softening under specific parts of the body can lead to the loss of comfort or support depending on the design of the mattress, the relative quality of the layers, and how much "room" you have for foam softening before you are out of your range in terms of pressure relief or alignment.

3. Lower ILD Talalay (i.e. 14) will break down quicker than 24 ILD Talalay, so even softer version of Talalay can cause issues sooner when in the comfort layer. This is why you caution people on getting "too soft" a comfort layer even with latex (i.e. Worlds Best Bed from PLB). You can never firm up a bed, but you can always "soften" it with a topper or something else.

Yes ... all materials including latex will be less durable in softer versions even though latex would be more durable than other materials with a similar softness. This and the fact that thick soft layers can be risky even without foam softening (they can allow the heavier pelvis to "travel" too far before it is stopped by the support layers while at the same time "holding up" the lighter parts of the body such as the upper back). part of the problem here is that few people test for alignment carefully in a showroom because much of what they feel is comfort and feel so when they end up sleeping on a mattress that felt great in a showroom ... they could end up waking up with a sore back because the alignment issue didn't show up in the showroom because they weren't on the mattress for long enough. Comfort/pressure relief is generally what you feel when you go to sleep at night and alignment/support is generally what you feel when you wake up in the morning. Some people who tend to have a much more even weight distribution and a more proportionate body type can do well on softer layers because they sink in more evenly (and are still in alignment because every part of their body is deeper in the mattress) but this is less common and for most people comfort layers that are very thick and soft are more risky. You need to remove layers and make them thinner or firmer if they are too soft because if you put a firmer layer over it it will just tend to "bend" into the softer foam underneath and will only have a temporary or partial effect on alignment issues.

Based on that, it would seen the OMF Latex Supreme may fit into this "too soft" category since it has about 1.5" of convoluted 15-17 ILD Talalay on each side of the mattress, plus some low density foam in the cove over the 32 ILD core. So the question I raised about (two sided vs. one sided comfort layer) still stands here. Thoughts on this bed or feedback from others who have purchased?

The material quality is good and the inch of polyfoam is quilted (which pre-compresses it and adds to durability). The convoluted Talalay is only 1.5" so with the polyfoam quilting the "comfort layers" are only about 2.5" which means that the top part of the 32 ILD core would be part of the "critical zone" for most people and then deeper than this would perform it's support functions. It would be in the softer range but the fairly thin and soft comfort layer means that you will be using some of the support layer as your critical zone which would firm up the actual support below this. Layer thickness and layer softness all play a role along with compression modulus (how fast a foam gets firmer with deeper compression) to determine the softness of the upper layers that are the actual critical zone. When you are dealing with such complex numbers (and the shape of the egg crate also affects the compression modulus of the layer) then personal testing is really the only way to know whether you are in good alignment. If this mattress "fits" in terms of PPP I would rate it as having good quality/value.

That seems to leave two options for us...the Rest Assured Innerspring beds or perhaps the Brooklyn Bedding latex that we can build with maybe a 19 or 24 ILD top layer over the 32 ILD core. Probably not recommended to go down to the 14 ILD on the comfort layer based on statement above, right? Two totally different beds I understand, but the Memory Foam is out for us and the other Innerspring beds we have seen (OMF, Restwell, Restonic) do not seem to be good options for various reasons both you have pointed out and based on our own testing. I guess this is what this site it is all about...eliminating the poor choice and winding up a few good ones.

I would certainly be cautious in most cases with 14 ILD and even with 19 ILD and tend to use these in thinner layers but this is also relative to body weight. 14 may be suitable for very light people who don't compress the layers as much or for those where durability is less important than "comfort". I would also keep in mind that a manufacturer will usually have the experience to know how all their layers interact together with different people so their customers don't have to analyze the effect of every layer, the quilting materials, and the cover in relationship to their body type which is probably outside of the ability of almost all people. You are right that more than anything the site is about the "how" of making a choice because there are so many variables that the "what" can only really be decided on an individual basis based on all the criteria that are most important to each person.

The one other items I would like you to comment on is this. Regarding alignment, I do not think my wife has laid on any beds that line up her spine from the neck to the tailbone when she is on her side (and she is a side sleeper...5" and 110 lbs). Her neck is always high than her tailbone even with different pillows. Her shoulders do not seem to "sink in" far enough and that is why she thinks she wants a softer comfort layer to help with that. Just struggling to make her happy, but that is the focus here as she is the one that really is having difficulty with our bed now. Appreciate your input.

In this case the comfort layers need to be thick and soft enough to "allow" her shoulders to sink in enough ... but "just barely". she may be in the range where 14 ILD may be a good choice. Without going too deeply into specs that can be more easily tested in person (and are very complex) ... the compression modulus of a foam is important here because it can be soft in the upper part of a layer but gets firmer quickly as you sink in more so it can be both soft and pressure relieving and supportive at the same time even in a softer material. With foams that have a higher compression modulus then you can still "allow" the shoulders until they sink in enough for the greater surface area of the torso to take up the weight but still "stop" the heavier pelvis from sinking in too far because it gets firmer faster as you go deeper. A higher compression modulus is the benefit of latex and HR polyfoams and some types of higher density memory foam. Beyond this type of "vertical zoning" that is a side effect of foams that have a higher compression modulus ... actual zoning that targets different areas of the body with firmer or softer zones are also very effective. The 3 main "zones" that are the most important are under the shoulders, under the recessed curve of the lumbar, and under the pelvis. Relatively firmer under the pelvis (either through higher compression modulus or through zoning), the same or a little firmer yet under the recessed curve of the lumbar (firmer is more important with more curvy body types or for people who have relatively wider hips or shoulders) and then softer under the shoulders.

For most people zoning is not necessary with latex because of its higher compression modulus (and Dunlop has a higher compression modulus than Talalay so softer Dunlop can provide the equivalent support with deeper compression as firmer Talalay) but with more challenging body types or circumstances or as a preference then zoning under specific areas can be very effective even with latex.

So, am I finally "getting it"?

Based on your comments and questions I would say a resounding yes :)

12 Aug 2013 14:33
  • phoenix
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Hi suprattmike,

So I think I've narrowed down my decision to a Talalay Latex mattress. I've picked 3 vendors from the Membership list.

Arizona Premium Mattress Co (AKA Mattress.net)

The Original Mattress Factory

Brooklyn Bedding (AKA Dreamfoam Bedding)

These are all good quality and value options but for the sake of clarity I should mention that The Original Mattress Factory is not a member of this site (you can see the membership list here and the members that sell online are listed here ). I would only consider them if you are local to one of their stores and can test the mattress in person because they are not set up to do layer exchanges and don't ship their mattresses by courier so shipping costs will be higher.

You have certainly eliminated your worst options and have narrowed down your options to final choices between good and good.

I can only speak to the quality and value of a mattress and help the members here identify any weak links in terms of durability and all of these are good value in their price range and have no obvious weak links. This means that you have reached what can be the toughest part of the process which is choosing a mattress between "all good" options where there are no clear "winners" and all the objective, subjective, and intangible factors that are part of every mattress purchase and that are uniquely important to you are the only meaningful basis for a decision. In terms of quality and value there are no "mistakes" left any more :)

Post #2 here has more about making final choices when all your remaining options are good ones and the only meaningful differences are the ones that are most important to you.

Some of the things I would consider are your confidence in the suitability of each mattress in terms of PPP and the options you have after a purchase in terms of layer exchanges or a mattress exchange and the costs involved if your choice is less than ideal. I should also mention that the Total Latex Mattress from Brooklyn Bedding and Amazon is the same mattress at the same price but the return and exchange policies are different (Brooklyn Bedding is less costly).

First, what's your opinion on the different methods Arizona Premium Mattress and Brooklyn Bedding use to adjust comfort?

I like them. They can exchange the support core of the mattress on each side which means that you can also affect the "feel" and pressure relief of the upper layers (all the layers work together). The differences between the methods used to adjust comfort and support and the options available are part of each person's personal value equation and some of the manufacturers here have more options to make changes than others. For some this is a benefit and for some it's less important. With this mattress you can exchange the firmness of the support core which affects the "feel" and pressure relief as well. I personally like mattresses that provide the ability to make adjustments at a reasonable cost after a purchase.

Arizona Premium Mattress uses a 22ILD Topper/Comfort Layer and then adjusts the ILD for the Core/Support Layer as needed. Whereas Brooklyn Bedding (basically, in most of their options) uses a 32ILD Core/Support Layer and adjusts the Topper/Comfort Layer as needed.

This will have a more direct effect on the pressure relief of the mattress and a secondary affect on support/alignment.

Basically, is it better to adjust the ILD of the Core or Topper? I thought (from my limited research) that you wanted a firm Core to provide needed support and then you could play with the Topper to obtain your desired comfort level?

There is no better or worse ... they are just different. Adjusting the comfort layer will have more of an effect on the feel and pressure relief of the mattress while adjusting the deeper support layer will have more of an effect on support/alignment. It depends on the type of adjustment that you may need. Both of them have the ability to choose different support layers prior to the purchase. All the layers of a mattress affect the feel and performance of every other layer but changing the deeper layers has more of an affect on alignment and primary support (the type of support that "stops" the heaver pelvis from sinking in too far) while adjusting the comfort layers will have more of an effect on pressure relief and secondary support (which fills in the recessed gaps in your sleeping profile). Some of the members here sell mattresses where both the comfort and support layers can be re-arranged or exchanged and have more flexibility yet but may also had additional cost.

Second, The Original Mattress Factory. It says they use Convoluted Talalay Latex as their Topper. How is that different from Blended Talalay?

The convoluted Talalay is blended Talalay. Convoluted foam is like an egg crate foam (see the picture here ). Convoluting will change the response curve of the foam making it softer on top where there is less material and then getting firmer faster as you sink into the thicker parts of the hills and then into the part of the layer that isn't convoluted. In technical terms it increases the compression modulus (the rate at which a foam gets firmer as you sink into it). The shape and depth of the convoluting are used to change the response curve of the material. Convoluted foams have less material (you can make 2 convoluted 2" layers out of a single 3" layer for example) and are less costly and would be less durable than the same ILD layer that is a solid material but the OMF mattresses are also two sided which increased durability. Durability wouldn't be an issue with any latex mattress because it is the most durable of the foam materials. Any foam (or type of latex) can be convoluted to change the feel and performance of the mattress.

Also, they put it on both sides of the mattress. One could think that would be a plus due to being able to flip the mattress/possibly obtain a greater mattress life. However, wouldn't the weight of us sleeping on the mattress + the mattress's own weight be bad for the Topper layer that ends up on the bottom?

In an apples to apples comparison between two mattresses that use the same materials of the same type and softness/firmness level ... a two sided mattress will be more durable than the same one sided mattress because the layer on the bottom has a chance to rest and is compressed more evenly and much less than the layers on the top which take up most of the wear and stress from sleeping on them. The softening of layers under the heavier parts of the body is the biggest reason for loss of comfort and support and this would reduce the softening of the areas under the greatest stress ... even in a material as durable as latex. The tradeoff with a two sided mattress is that there is less flexibility of design because you can's use thicker layers or more sophisticated progressively firm designs because if you have too mush soft foam on the bottom of the mattress (the support layers) you risk alignment issues. With a mattress that has a replaceable top layer you can also replace just a single layer if it softens or breaks down faster than the deeper layers of the mattress without having to replace the entire mattress.

I also noticed that both the Original Mattress Factory and Arizona Premium Mattress use around a ~20ILD (17-21 for OMF, 22 for APM) for the Topper. Isn't that too soft for most (I know that's preference, but it still seems to be pretty far over on the soft side of the scale)? Although it's less relevant to Arizona Premium Mattress depending on your answer to if it's viable to adjust the Core ILD.

In a single word no (if it was they would certainly have changed their designs over the many years they've sold them). The thickness of a layer, the softness of a layer, the quilting of the mattress, and how all of these interact with the layers below all affect the feel and pressure relief of the mattress. With thinner top layers then the firmness of the upper part of the layer below becomes part of the comfort layer. All of this is part of how mattresses are designed in different ways and here are many pathways to the same end result in terms of PPP. A mattress that uses a two inch comfort layer over a softer support core can be very similar to a mattress that uses a 3" comfort layer over a firmer support core for example if the top 3" of the mattress are the comfort layers for a particular person (each person will have a different depth of cradle which is their "critical zone" for pressure relief).

Hope this all helps and when you are down to final choice I would make sure that you compare all the different factors that are part of every mattress purchase which of course includes price, type, quality, and amounts of materials, the options available to make adjustments before and after a purchase and the cost involved, and all the other factors that have "value" and are important to you.

24 Jul 2013 14:13
  • phoenix
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Hi sleeping,

I appreciate you listing a few of the basic specs of their designs but just for the sake of clarity in case anyone takes these combinations too seriously or as an "optimal" design on an individual level ... these are just starting points or initial reference points and are often not the final design for one of their mattresses which are (or were) usually based on more detailed discussions, input, preferences, and measurements. They often provided two options in terms of layering depending on the preferences and specifics of each person that isn't part of the input into the basic profile. These specs would also be more typical for side sleepers. In some cases with certain people they even use a unizone layer in certain circumstances.

Personally, I like the idea of a 2" inch comfort layer. I think the 3x3" and 4x3" builds risk the cradle being too deep and/or not progressively firm enough in the cradle depth.

I would keep in mind that the thickness of a comfort layer is not directly connected with the depth of the cradle (or what I call the critical zone) because all the layers interact together and even the firmness of the middle and lower layers contribute to the depth of the cradle to differing degrees depending on the body type and sleeping style of the person. With a thinner 2" comfort layer you can adjust the depth of cradle by varying the firmness of the layer below it and with a thicker comfort layer then you can often use firmer middle and/or lower layers because the greater compression of the thicker top layer creates more firmness in the layer (because of compression modulus) which allows for a smoother transition between the thicker upper layers and firmer deeper layers and reduces the compression and "contribution" of the deeper layers. In other words each design has it's own advantages and disadvantages and one is not inherently "better" than another.

Generalizations and theory based on averages can be useful as a starting point but they often lead people that don't fully understand all the many variables involved to believe that a certain "design" inherently works better on an individual level and then come to believe that "theory" is a better way to predict their "perfect" mattress design than their own personal experiences or more detailed conversations with a manufacturer. I don't think that there is any inherent "risk" in a 3" comfort layer and it has more to do with how any specific top layer interacts with the deeper layers below it in combination with the specifics of the person than it does with the actual thickness of a comfort layer itself. Isolating a single part of a design without taking into account how it affects and interacts with the rest of the design can sometimes be misleading. You could have a 2" comfort layer for example which provided a depth of cradle of 4" under a certain part of the body and a 3" comfort layer that provided the same depth of cradle with a different combination of ILD's. Theory is great as a starting point and as a step towards an "ideal" design but it's not so good at including all the individual differences, variables, and preferences that can lead to the "best" design for any individual person and in some cases it can lead to people trying to design their own mattress without understanding all the variables involved which can have some unfortunate and in some cases costly consequences.

Maintaining some degree of uncertainty and having good exchange options after a purchase when you haven't actually tried a mattress is just as important as having certainty when you are dealing with theory because it can prevent unrealistic expectations and an undue focus on mattress specs vs personal experience or the knowledge and experience of a manufacturer who has the experience and instincts that help them know when to "break the rules" and when to follow them.

28 Jun 2013 18:52
  • phoenix
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Hi sleeping,

First of all I should preface this rather long post with a few comments so that you don't in any way see it as being critical ... which it certainly isn't. Your comments do provide a chance though to share some thoughts as "food for thought".

It's also clear to me from your posts that you have some good experience with various layering combinations and a good analytical mind so your posts are certainly helpful, informative, and insightful ... and of course very welcome :)

Just to clarify my "approach" and some of the background intent of the site though ... especially as it regards complete DIY constructions (which I generally tend to discourage unless someone has realistic expectations of what may be involved) ... some comments about the underlying goals of the site and forum may be helpful.

One of the initial goals of this forum ... and one of the things that was intended to make it different from say WTB where I also used to post frequently or other forums or review sites ... is that I wanted to emphasize more accurate, factual, and educational information that put more of an emphasis on "connecting with experts" with years of learning and experience rather than a forum where dozens of conflicting opinions by a well meaning group of consumers made it difficult to differentiate who had the knowledge and experience to really help people and who was just posting opinions which were presented as fact (which were often either factually incorrect or misleading although of good intent). I used to see long threads in other forums with a mishmash of conflicting advice which tended to do more to confuse people than help, and would often make it difficult to differentiate between knowledgeable members who could truly be considered "experts" and those who were just presenting or passing on strongly held opinions based on a few weeks of research or experience and which often contained ideas that they had "heard" and come to believe (rightly or wrongly) and that often had little relevance for the majority of people.

This was especially true in the case of some of the DIY threads where I used to cringe at the type of advice that was often presented as factual which often overwhelmed or "confused" the advice that was given by some of the more knowledgeable members because it seemed to have equal "weight" or legitimacy. In some cases (as is very common in the industry) there was also conflicting advice provided by members who were even in the "expert" group who would all make good points but the advice would sometimes be completely contradictory. This would often lead to complete confusion and the member who was seeking advice taking a very scattered and non systematic approach that jumped from one suggestion to another or from one extreme to another with no progressive testing and "learning" pattern. I would see layering changes that were "correcting" the wrong thing completely (such as people adding firmer top layers trying to improve "support") and in some cases it was obvious from the beginning that they would have little chance of succeeding in their design goal because their basic assumptions were just not correct.

I would also often see people becoming too fixed on certain ideas that they were excited about because it worked for them and turning basic guidelines into "rules" and where you would see statements like "Talalay is better than Dunlop" written by someone who preferred Talalay or where Talalay worked for them and that had no information about "better in what way" or "better in what circumstances". Other examples were along the lines of "this type of construction" is better than "that type of construction" written by someone where the type of construction they were "suggesting" worked well for them ... even though it may not have worked at all for someone else. All of these can sometimes lead to someone jumping to a conclusion that is not appropriate for them.

Mattress construction is so individual and often counterintuitive that there is always a risk as soon as someone turns concepts or guidelines into specific recommendations or "better / worse" interpretations that don't include specific reference points of someone's personal experience or preferences. My question in these cases is always "better for who?" or "better why?". In addition to that ... if too many people become involved in the "advice giving" process for the same person ... even if they are all knowledgeable ... or if their advice is conflicting in some ways because each has different experiences or are focusing on different pathways or different elements of the overall design goal, then it often does more harm than good because the person seeking advice can end up "jumping" from one idea to another in a much more haphazard way and never include the whole picture in their thought process and use a slow and incremental or step by step approach to assess and learn enough from each combination to make the most logical and highest probability choice for their next one. In these cases it can become difficult or sometimes impossible to reach an ideal combination except perhaps by a random stroke of luck which may or may not happen. They will often jump right over the most suitable layering going from one extreme to another and end up giving up or settling for a layering choice that never really works well for them. I have always preferred presenting options that outlines the pros and cons of each choice.

In most cases a DIY approach has the best odds of being successful by duplicating a specific design in terms of layering and materials ... including the cover ... that has already been proven to work well for the range of body types and sleeping style that the person falls in. These more "standard" designs (whether they are 6 + 2 or 3x3 or other combinations) have been developed and proven to work over many years for a wide range of people and it's often when people start "tweaking" things in different ways based on incorrect assumptions or information; theory that may not apply to them specifically; lack of knowledge or personal testing experience; not taking the effect of all all the design factors, layers, or components into account; or because they're not familiar with the real life effects of making certain design changes that they run into trouble.

In other words ... the complexity of too many ideas, options, and theories often overwhelms them and they focus on theory more than their own personal experience.

For the minority who are much more sensitive to small variances in design and where standard designs don't work as well for them ... then the most successful way to approach a DIY construction is with personal testing (either in a store or at home sleeping) and using their specific experience on each combination to make small incremental changes in a specific "direction" because the "standard" advice that would work for most people tends not to be as successful for them. They are "outside the averages" in other words and in these cases changes may often need to be "outside the norm". In most cases only their own testing and sleeping experience can really identify what combination will work best for them.

There are many "standard" combinations and designs that use a different pathway to a similar result that may work equally well for people in terms of PPP. For example a 2" layer with a softer 6" base layer may be very comparable to a 3" top layer with firmer 6" base layer underneath it for some people so in cases like this there is no "better" design in terms of layer thickness because it depends on the specifics of what else they are combining it with. Too much emphasis or focus on ILD without enough consideration of layer thickness or compression modulus (or other design or material factors) or too much emphasis on layer thickness without consideration of ILD and other factors can often lead to poor results. Personal experience along with specific feedback targeted on identifying specific symptoms and the most likely underlying cause behind them can often bypass the need for much more complex knowledge about how many interacting factors work together. In many cases "educated intuition" and experience can be more accurate than technical knowledge that tries to take too many interacting details into account.

The guidelines I normally suggest of "about" 1" stomach, 2" back, and 3" side sleeping (all +/- an inch or so and sometimes more depending on the many other factors involved) are also not so much about specific layers but as much to make a point that certain sleeping positions need different designs, depth of cradle or what I call a "critical zone", and a different balance between comfort/pressure relief and support/alignment. They are more starting points in other words meant to give generic insights into mattress constructions and design ideas that may provide the basic knowledge to have more meaningful input into discussions with a retailer or manufacturer than they are specific ending points or recommendations. It's also true for example that a single layer may include the necessary range of comfort and support in a single layer and have say a good 2" pressure relieving cradle and good deep support (because of good compression modulus) in a single layer that has no separate "comfort layer" at all. A mattress that has a 2" separate comfort layer may provide a 4" cradle in some combinations and a mattress that has a 4" comfort layer that was very firm may provide a 2" cradle for some body types and sleeping positions.

So the simple and often most successful version of a DIY mattress is normally to copy a successful design that is proven to work well and is a standard layering of a successful manufacturer for that person's body type and sleeping style regardless of the specifics of the design. Again ... different designs can be different pathways to a similar result. This could be a 6" + 2" design from one manufacturer, a 3x3 design from another, or a single 6" layer with a box spring or flexible slats under it from a third ... all of which may be roughly comparable in many ways and work very well for the same person.

Once you start straying from successful designs ... sometimes in incrementally smaller ways ... the odds of success begin to decline. If someone's sleeping experience on a certain combination that would work well for most people with a similar body type and sleeping style doesn't work well for that person because they are outside "average" ranges ... then the most successful way to complete the DIY at the least possible cost would be to use their own specific sleeping experience and "symptoms" on the "wrong" mattress to one step at a time try to analyze and predict what has the best odds of transform the "wrong" mattress into the "right" one. This may need some careful analysis about why that person may be different from the norm and some very specific and targeted feedback about their symptoms and how and where the mattress needs to change.

In most cases more extended and interactive voice communications that can pick up on the nuances or finer details that can make a difference may be necessary (assuming that's available). It may often also need "organized" trial and error with the "expectation" of mistakes because "averages" are no longer applicable and this is the stage where complete DIY can become costly if the "averages" don't work for someone or frustration begins to creep into the picture which tends to lead to hasty conclusions in an attempt to "get it over with". If you have purchased from a foam supplier where what you purchased was "cheap" but can't be returned or a return involves significant costs ... a complete DIY can become an expensive lesson in mattress design as it applies to a specific person.

DIY can certainly be a great approach that has some unique challenges and rewards but I think that in most cases and for most people the goal of complete DIY is not so much to "tinker" or create a unique design as it is to find a cheaper way to accomplish the same thing as a kit produces. Once you need to return a single layer (if returns are possible) and/or pay for shipping or restocking fees or incur other costs, the main benefit of a full DIY approach may be lost. Tinkering can become very costly for those who don't get it right the first time which in most cases defeats the main reason that people choose a complete DIY construction in the first place. For those who don't mind the cost of multiple mistakes and their goal is more of a learning process vs a lower cost way to build a mattress then of course this wouldn't apply.

In the case of this particular OP ... they are already starting off with a disadvantage compared to "kit" designs because they are using toppers stacked on top of each other rather than layers enclosed in a single tight fitting cover which is already a design change that can affect how specific layers perform individually compared to the same ILD's inside a mattress cover. Even the choice of a soft layer with such a wide range indicates the potential for trouble depending on which end of the range the 17 to 27 topper may be because it doesn't provide a narrow enough reference point for any changes that may be necessary.

Some other examples are that Dunlop in a core is only a good idea for someone who prefers Dunlop. It's not a good idea for someone who prefers Talalay or even someone where Talalay may provide specific benefits that for them would be better than Dunlop in their specific application so the qualifier becomes important. This puts the onus and responsibility on the person to make sure they choose wisely and have tested both rather than putting the focus on the "theory" that one is better than another in any specific circumstances when it may not be ... they're just different. A lower compression modulus can be useful in some circumstances. I also believe that it's also important that a person that is working with a complete DIY feels some "uncertainty" about making the best possible choices so that they keep their expectations realistic and they have realistically assessed their risk tolerance. Those who are too confident about DIY success or who become too confident that certain theories may be successful for them can make decisions that are not as carefully thought through or elevate theory over their own personal experience. Overconfidence can lead to some of the worst "mistakes" and a good dose uncertainty and a realization that they are working with odds rather than certainty is an important part of success and realistic expectations IMO.

So there are certainly guidelines that are very useful and ideas that can be extremely helpful but as soon as these cross the line from "pros and cons" into "better worse" so that people realize that every benefit has an opposing tradeoff then they may be taking the first step along the path of disappointment and frustration. My goal has always been more to help people with "how" to choose rather than "what" to choose.

So hopefully this has provided some insights into some of the thoughts and ideas behind the site and the forum that have developed over a learning curve that has been very steep and challenging and continues to progress just as rapidly over time.

So thanks again for your thoughts, insights, and posts so far ... and I'm grateful for your ongoing contributions to the forum community :)


PS: Just as a point of clarification ...

The vendor is SleepEZ on eBay. I would call SleepEZ direct first to talk it over.

The mattress cover is from SleepEz but the vendor is not SleepEz and is an independent retailer.
03 Feb 2013 22:08
  • phoenix
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Hi sleepy1,

Yes, I see what you mean. However, the mattress we tried and loved locally had 3" med Dunlop as the top layer; you could argue it had no "comfort layer" at all! Yes, extremely firm. So I guess I want to "blow through" the comfort layer and hit that med Dunlop that I loved, to make sure I don't lose alignment. And having 2" of softer latex over the med Dunlop will certainly be softer than the med Dunlop alone. Does this make sense? I'd just rather err on the side of too firm, given my own needs/preferences.

The 3" layer on top would be the comfort layer in this case. Even a mattress that uses a single 6" layer of latex would have a "comfort zone" even if it wasn't a separate layer. I use "layer" because the most common design is a separate layer on top but this isn't always the case and "comfort zone", "critical zone", or "depth of cradle" would be more accurate. Either way ... the top few inches are the comfort zone (which in this case could be called the "comfort layer" regardless of its firmness). I would tend to lean towards the design that your personal testing indicated works best for you in terms of the balance between pressure relief, support and alignment, and your personal preferences. A mattress that used exactly the same layers with the single exception that the top layer was an inch thinner would have a different feel and performance than a mattress that used the same layer thickness.

The goal of a "comfort layer" is not so much to "blow through" it (although in some cases this is part of the design goal) but to control the degree to which the layers below it contribute to both the depth of the cradle (for pressure relief) and secondary support (the support that "fills in" and more lightly supports the more recessed parts or "gaps" in your sleeping profile). All the layers in a mattress affects how every other layer both above and below it reacts and they all interact simultaneously even though it can help to visualize how a mattress may perform by imagining them compressing sequentially from top to bottom. This is all part of the "art and science" of mattress theory and design and people who have been designing mattresses for decades will tell you that their learning curve is still ongoing.

The advantage of using a thinner layer as you mentioned is that it will be a little firmer (all else being equal) and the depth of compression would be a little less. This means that primary support would be higher (the deeper support that "stops" the heavier parts from sinking down too far) and pressure relief and secondary support (that come from the depth of the cradle) would be a little less. You would retain the option of adding a topper if your experience on the mattress indicated that you needed it. As soon as you start changing a design from what you have tested there is some fairly complex "translation"involved in terms of how it will affect different people (variations in layering will affect different people differently because each person will feel the effect of different layers differently based on their perceptions, body type, and sleeping positions).

The cover on the SleepEZ appears to be nearly identical to the SavvyRest cover: 1" wool quilted to cotton. I loved this too. And yes we will definitely be doing split layering, as I mentioned above.

Yes ... they are very similar although I have seen feedback that he SleepEz cover is a little nicer and less "stiff". Each of these may also change their cover from time to time as well as new designs and components become available but they are certainly "similar".

Yes, no one seems to believe that I need a harder mattress than my DP, who weighs 100+ more than me. But it is thus! :) I've already had one conversation with SleepEZ and he said the same thing, that DP will need firmer layers than me. Oh well. And I am sure about my preference for firmness; for example, years ago I helped my mom select a twin guest bed, and since I would be the most frequent guest, I chose what I liked. I finally had the guy pull out a hotel-quality extra firm w/ no pillowtop that he swore no one wanted because it was rock hard. I loved it, we bought it, and I've never slept better than on that mattress.

This seems to be counterintuitive but it's not unusual at all. People who are lighter ... especially if they are fairly slim and tall ... will often fall on either end of the firmness scale. Some tend towards softer than average because their lighter weights need softer foams to sink in to the same degree as heavier people. In other cases those who are lighter don't experience pressure issues to the same degree (their weight and muscle tone reduces the likelihood of pressure issues which comes from compression of capillaries) and they prefer to be more "on" the mattress and have more freedom of movement. This again is part of the 'art and science" of mattress design and theory and how each different design can work very differently for people who are otherwise very similar.

Thank you. We can purchase a coir bed rug at our local SavvyRest dealer for $79 queen. Seems like a decent price and at least we can give them some business. Will this take care of the problem?

This is a good "risk reduction" idea IMO and yes it would take care of any potential problem.

20 Jan 2013 18:36
  • phoenix
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I am a side sleeper, 5'10" weighing in at 165lb. My wife is 5'3" back sleeper weighing in at less than me. My thinking is 9000 because 2" of soft Talalay is plenty, 3" as in the 10000 might even been stifling. Med middle core for me; firm middle for her (lighter back sleeper). Extra firm bottom layer or possibly extra firm and firm for more combinations - not sure about this. Any thoughts?

While I don't think that most people would find 3" of latex in the comfort layer "stifling" each person can have very different ideas about what they prefer. I would always go with the suggestion of the manufacturer but in "theoretical" terms ... a 2" soft upper layer with softer layers below it can be roughly equivalent to a 3" upper layer with firmer layers below it. In other words ... it's not just the thickness of the physical layers themselves but the depth of your pressure relieving cradle or what I call your "critical zone" which is the amount you will tend to sink into the mattress regardless of the actual layer thickness. This will vary with different combinations and ILD's of the layers. This is discussed in the "mattresses" section of the site under progressive and differential construction.

Unless you have specifically tested a specific combination of layers in person so that you are very familiar with your own specific needs and preferences and the layering that produces it ... I would always tend to talk to the manufacturers themselves and go with their best suggestions.

03 Dec 2012 21:51
  • phoenix
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Hi HolisticallyYours,

My husband did stop at Restopedic and tried an all Latex however they do not have a huge selection so he was limited to firm. He did not have the time for them to put other ILDs on top but he was wondering if one could get a good sense doing it that way. They are not close enough for me to go to unless we know exactly what we want. But they seem very honest, nice, and accomodating. I think we are out of their delivery range too, but will keep it an option.

Yes ... this can give you a good sense of different layer combinations although the ticking/quilting fabric will also make a difference. As you say they are good people.

I am 5'3" and 112 pounds, my husband is 6'2" 185 pounds. We are thinking of buying 2 separate mattresses as our schedules vary dramatically. If we were to go with a split top would this affect the integrity of the strength of the latex? I am thinking I should get a mattress to suit me that would not kill him for the few times he will use it!

No ... a split top doesn't compromise durability but it does usually require some kind of layer over it (either in the quilting or in the comfort layer) so you won't feel the split (athough you will of course still feel the different firmness levels on each side).

It can also be surprising to some people that certain layering combinations can accommodate different weights/heights in the same mattress. For example ... a middle transition layer can act as more of a support layer for the person with the lighter weight while it can act as more of a comfort layer for the person with a heavier weight. In some cases ... people that have very similar body types and sleeping positions may prefer different layering while couples that are very different in body type and sleeping positions sometimes prefer the same layering. Sometimes all the many variables involved converge together and can lead to the same layering for different people ... even though it doesn't seem "logical". This is part of the reason that personal testing can be much more accurate than designing a mattress based on "specs" which often only cover a few of the many variables involved in what makes a mattress more suitable for a particular person. In other words there is no "formula" where you can plug in specs (either of the person or the mattress) and come up with the "best" mattress although they can help with fitting people into "averages" that many will do well with.

I visited the place in Northampton MA to look at Berkeley Ergonomics and Latex International's line of Pure Latex Bliss. With the Berkeley I liked the Alpine with the 2 different sized coils, however felt that the top layer of latex 2" was not thick enough. The firm side felt good- the soft side felt too soft, but this may be a function of me coming from sleeping on a "rock" of a mattress where I wake in pain everyday.

They can alter both the support components (different innersprings or latex) and the comfort components (microcoils or latex) of the mattress so that you can have the best possible combination of both. Was the firm side the one you thought the comfort layer was too thin? There are some counter intuitive processes at work sometimes in a mattress where for example a softer thin top layer can allow you to "go though" it more and feel the firmness of the support layers while a firmer comfort layer can isolate you more from the support components and feel softer. Thickness and softness of the comfort layers and how much they "isolate" you from the firmness of the support layers (or in some cases how much the qualities of the support layers "contribute" to the comfort layers) are all part of creating the balance between pressure relief and support/alignment. The "critical zone" or "comfort zone" of a mattress (the depth of the pressure relieving cradle that you need) may be partly formed by the upper layers and partly formed by the softer part of the support layers below it so where the "boundary" between the layers may be can be misleading.

My husband feels if you are getting a mattress with latex then why get coils go with all latex- any thoughts?

The choice between a latex support system and an innerspring support system is really a matter of preference. One is not necessarily "better" than the other. Innersprings have a more linear response (which can be changed with different spring designs) while the response curve of latex is more bananna shaped and innersprings also have a higher resilience (they return more energy without absorbing it) than latex. In addition to this some innersprings have variable spring rates (similar in a way to say a 6" firm layer of latex with a softer 1" or 2" layer on top which is then used as the base for the comfort layers above it) which acts differently again and there are many other variables between the two. Some people may just do better with or prefer one over the other and each type of response may work better for some people.

Some people that can't make any combination of latex layering work for some reason may do well with latex over an innerspring for example while others that don't seem to "match" any type of innerspring may do well with an all latex mattress. I do think it's true that those who prefer all latex would probably not go back to an innerspring but there are some who just don't do as well with all latex.

Based on your recommendations, I should be on a low ILD like a 19? He was saying I was on 38 ILD firm 24 soft side on the Alpine and my alignment was pretty good- this made me highly suspicious of the ILD numbers he was giving, why would anyone put 38 on top?

Just to be clear ... I don't make recommendations but just provide guidelines that can be used as a reference point for working with a manufacturer or for local testing. There are just too many variables between body types, sleeping positions, preferences, and how all the specific components of a mattress work together (besides just the ILD of the latex) to make any kind of meaningful recommendations based on any formula or what I call "theory at a distance". It would generally take me several hours of much more detailed conversations that try to take into account many factors to try to design a mattress for someone based on specs and even then the ideal design as often as not wouldn't be available anyway and in some cases individual preferences and details that hadn't been considered could lead to different choices once they'd slept on the mattress anyway. Theory is an approximation based on averages at best.

The more specific recommendations I leave for discussions between manufacturers or retailers and their customers because they have much more detailed knowledge of the finer details of all the materials and components in their mattresses and perhaps more important, what they have available to choose from (they usually have a set of standard layers and components that they use). They also have a customer base that they can use as a reference point for the specific mattresses, materials, and components that they use.

The more specific "suggestions" I do make are usually limited to situations where there is a specific reference point of a complete mattress and a single layer needs to be changed or symptoms need to be resolved based on a more detailed description of the "symptoms" involved or on various choices of toppers that may need to be used for fine tuning. Without this reference point of a specific mattress that someone has tested or slept on that produces certain "symptoms" then I limit the information I provide to explanations about how each different layering or combination may affect certain people so that they have a better idea of all the "moving parts" that are involved. For example .. there are many manufacturers that don't even offer 19 ILD in latex because they believe it is too soft and their softest "standard" materials may be in the range of 24. Most of these could probably special order 19 ILD (they certainly have access to it) if necessary but they tend to design around slightly firmer comfort layers.

I would trust the information BE or any of their retailers give you. They (and most of their retailers) are among the most knowledgeable and open manufacturers in the country. There are many instances where the use of firmer latex may be appropriate either by itself or as part of layering arrangement that involved "dominating layers" (firmer layers over softer layers or innersprings). While I personally and I think most other people would have trouble with a latex comfort layer that was all 38 ILD (and didn't have other layers or components as part of the comfort layers), there are some who wouldn't have it any other way. Personal experience and trusting your body over any specs is always the key.

Would you have the ILD info on the all latex Berkeley MEDIUM firm Mattress?

I don't know for sure but I believe their soft latex is @ 25 ILD, their firm topper is @ 37 ILD, and their base latex layers are @38 ILD. the firm topper would be softer on an innerspring than on their firm latex base layer (which is the firmest mattress they have).

What I couldn't believe is how different each of these felt- you were right you really have to try them out. I guess I agree with my husband the 100% all natural latex really felt the best. My concern is the condition of the sample mattresses- they were 5 years old and showed wear, tears in the covers at the quilting stiches and even stains- YUCK.

Different combinations of materials and components ... and sometimes what seems like minor changes ... can certainly make big differences in the feel and performance of a mattress. When someone is testing mattresses in person ... I would tend to completely ignore ILD information and go by what I was feeling. A focus on specs can get in the way of accurate testing IMO when you are lying on mattresses. If they are a curiosity then I would first choose the "best" mattress and then find the comfort specs out afterwards as a matter of interest. The "comfort specs" are really only important in an online purchase where they have to replace personal experience and even then the final test is when you sleep on the mattress.

The nice thing about Berkeley is the Chemical Freeness but I can't find info on whose Latex they use.

They use Radium as far as I know.

At the end of the day I am undecided on All Natural versus the synthetic blend, although I believe they are both Oeko-Tex 100 certified. I do want something that is safe but I don't want to shortchange myself buying something that is 50% more that won't last as long which is just as safe as the alternative.

This article along with post #6 here and post #2 here and post #6 here may help you choose between them.

Secondly, I need to determine the best ILDs and without a new mattress to sample or legitimate ILDs to go by I am stuck in the mud! Afterall, it is 51 degrees here today! If this helps, I did like the Beautiful 12" by Pure Latex Bliss but am uncerain about the covering which passes the fire standards. I would prefer organic cotton which will burn to something that will melt to me and the fumes will kill me in a fire!

Again when you are testing locally ...I would ignore ILD's and only find out after you had decided which mattress worked best for you if the ILD's were a matter of curiosity.

PLB uses a fire barrier which uses Viscose (Rayon made from wood fibers) and Silica which are both safe materials IMO and either this or wool would be my choice of fire barrier because they don't use chemicals. You can see more about fire barriers at the end of this article and post #2 here .

Could I use these specs to figure out what I need? Just want to get clarity on the Berkeley medium specs to make sure it jives. Does the Bliss use all natural latex NR? Is the Paladan layer Oeko-Tex Certified?
PLB - Beautiful
LatexBLISS uses 450-480 Gram Weight fabric
LatexBLISS Milliken?s Paladin Fire Resistant Barrier
3" Natural Talalay Latex 19 ILD
2" Natural Talalay Latex 24 ILD
6" Natural Talalay Latex 36 ILD
1" Support Stabilization Base @50 ILD Firm Talalay latex

Pure Latex Bliss has two separate lines of all Talalay latex mattresses. Their natural line uses blended Talalay. Their "all natural" line uses 100% natural talalay. The specs you listed are from their previous blended Talalay line before the recent change which removed the bottom 1" layer and added it to the second layer from the top in all the models except in the Pamper where it was added to the top layer and which also replaced the blended Talalay top layer with Active Fusion Fast Response Talalay (which used to be called Celsion and is called Talalay GL fast response by Latex International which makes their Talalay latex). Hows that for some confusing terminology? :)

You could use this as a reference point in your discussions with a manufacturer yes (along with all the other things that would help them to help you make a good choice) to let them know that this layering was "perfect" (assuming you had tested for both alignment and pressure relief on it) but since a manufacturer may not have the same thickness and ILD's of layers available or the same cover or the same fire barrier or even the same latex supplier (there would be some differences between suppliers) ... they may have to "translate" these specs into a combination they have available and the closest "match" may be an approximation. It would be helpful to them (and you) though as a guideline.

In looking on the Oeko-Tex site ... Milliken is listed (who makes the Paladin fire barrier) listed but only for labels. I also found Sateri listed (which makes Visil which is also a cellulosic/silica inherent fabric) but only for their fibers. Spaldin uses Visil and their entire mattress is Oeko-Tex certified. Either way I would consider both of them safe.

Hope this helps ... and I would strongly urge you to focus less on specs with local testing (except as a curiosity) which can be much more complex than you may realize and can easily lead to "paralysis by analysis".

20 Mar 2012 22:34
  • phoenix
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Hi Kai,

The Beautiful specs are ...

3" Natural Talalay Latex 19 ILD
2" Natural Talalay Latex 24 ILD
6" Natural Talalay Latex 36 ILD
1" Latex Base

The Nutrition specs are ...

2" Natural Talalay Latex 19 ILD
2" Natural Talalay Latex 28 ILD
6" Natural Talalay Latex 36 ILD
1" Latex Base

As you can see ... the beautiful has about 5" of "soft" latex on the top (24 or less is considered soft and LI calls 19 "plush" and 14 "super plush") while the Nutrition only has 2" of soft with 2" of medium and then 6" of extra firm. Layer thickness can have as big an effect on the softness of a mattress as layer firmness can so the 5" of "soft" latex over the extra firm base on the Nutrition would be much firmer ... than the Beautiful.

Adding the 2" ultra plush topper on the Nutrition would still give you only 4" of "soft or less" latex over the support core and because it is softer ... you would compress it more and be "resting on" or feeling the extra firm support core more than with the Beautiful. With 3" ... you would likely be resting "in" a lot of soft latex and not going through and feeling the firmer core quite as much which could result in a less stable feel (as you mentioned the sense of firmness underneath would become more vague).

With a heavier weight ... you will go through softer layers more easily and what I call your "critical zone" (the depth of the cradle needed to provide good pressure relief) would likely be in the 4" range. More than this and you would be more "floating" on soft latex on your back which doesn't have the same sense of stability as a thinner comfort layer.

It's difficult to quantify all of this exactly because all the layers will compress simultaneously based on their progressive firmness, thickness, ILD, and how much pressure reaches that particular layer (some of the weight is dispersed in the mattress and doesn't "reach" the layers below it) but the pressure relief and the "feel" comes from a combination of the ILD and the thickness of the comfort layers and how they interact both with you and with the firmer layers underneath.

they tossed in a waterproof mattress protector with the bed. Do these things take away from the bed's comfort? I have never used one before. Then again, I've never had a bed this expensive before. The salesperson advised against using a mattress pad as it forms a layer between myself and the latex and the whole point of spending this kind of dough is to experience the latex. What do you think? I currently have a premium cotton mattress pad that I really like.

The choice of a mattress pad is really about tradeoffs between three factors (other than just the feel or "hand feel"). One of these is breathability and how it contributes to the microclimate and temperature control of the mattress, the second is the degree of water resistance or water proofness of the protector, and the last is the amount it contributes to (adds to or detracts from) the feel of the layers on top of the mattress ... in this case soft latex.

The advantage of the thin protectors is that they have a membrane that allows water vapor through but not moisture so they are classified as "breathable" and waterproof. Because they are thin ... the better ones (that use a more stretchable fabric attached to the membane) and that are attached with a stretch pocket rather than encasing the whole mattress don't create as much of a drum effect and can have less effect on the feel of the mattress itself than other protecors. Of course they will affect the mattress more than no protector at all but doing this takes the risk of staining the mattress which would void any warranty. What they give up is breathability and microclimate/temperature control (the membrane is not as breathable as a natural fiber) so they can contribute to sleeping hotter.

Thinner wool protectors such as the Dormeir can also be very flexible ... and are water resistant rather than waterproof and they are also very breathable and provide a much better microclimate/temperature control. If they are thin and stretchy ... they have less effect on the latex than a thicker mattress protector or pad. Wool is more resilient than most other fibers but can still compress over time which can increase its firmness and the effect on the latex.

A cotton mattress pad is very breathable but is not as water resistant as wool or as the thinner membrane protectors and firmer feeling than wool. They protect from staining but give you less time to remove everything in the case of a larger spill. How much they affect the latex would depend on the thickness of the cotton, how it was made (quilting pattern etc) and how much it has compressed. Cotton is not as resilient as wool so compresses more easily.

If waterproof or water resistant qualities are not as important to you and temperature and breathability is more important ... then I would probably use the one you have as long as it wasn't too thick or firm and clearly affected the feel of the latex. The membrane types have a variety of different effects on the latex below (depending on how flexible they are, and on how much of a drum effect they and the method of attachment create) but if yours is stretchy and on the top only ... it may be worth trying as it may affect the feel less than the cotton at the expense of temperature control.

I think that in many cases poor reviews of a mattress have as much to do with poor choices than they do with a poor mattress. If someone chooses a mattress that is not suitable for them and they don't have good pressure relief or ar uncomfortable or have a back ache from poor alignment ... then the review is typically bad even though the mattress may be very high quality and just wasn't a good choice for that particular person. I generally pay little attention to reviews unless there is a clear pattern in longer term reviews (which are far less common) that lower quality materials were used in a specific mattress that led to actual quality problems of some type. "Comfort" reviews are mostly meaningless whether they are good or bad because all they say is that a particular person made a good or bad choice for them rather than chose a good or bad quality mattress. Of course reviews about the service of a particular outlet and how they deal with various issues can be quite helpful.

22 Jan 2012 23:08
  • phoenix
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Hi DanielH,

This should be an interesting project :)

Your height and weight certainly help (lower weights than average) but it would also help to know a little bit more about the types of mattresses in general that you have been most comfortable with to get a sense of your preferences as well. Do you like sinking in more deeply, do you like firmer (more on top of the mattress), do you tend towards pressure issues, do you have back issues. All of these and other guidelines from your history would help to narrow down the "best" theoretical construction for you.

Is a differential mattress construction to be absolutely avoided for side/back sleepers?

What I have called "differential" and "progressive" constructions are really different pathways to the same end which is good pressure relief and alignment. The differences between them don't have clearly defined "edges" but are more of a general approach to layering.

Each person needs a pressure relieving cradle which is deep enough and conforms to their body shape enough to relieve pressure points below their pressure tolerance. Lets say for the sake of argument that this cradle needs to be 3". This would mean that a 3" comfort layer that was soft enough to provide most of this pressure relieving cradle could use a much firmer support layer below it. A comfort layer that was only 2" in this case wouldn't by itself provide a deep enough cradle and if the layer below it was too firm you would "go through" the top layer and your pressure points would be supporting too much weight on too small an area because of the firmer layer below it. While all the layers of a mattress compress simultaneously ... it helps to visualize this to think of the layers compressing in a certain order (first the top, then the next etc). In a case like this ... you would use a softer support layer to help form a deeper cradle. If the comfort layer was already soft and thick enough ... then it wouldn't need any help and the support layers could be as firm as you needed them to be for best alignment.

Typically a comfort layer will come in about 1" increments which means that in most cases you need to choose between 2" and 3". Adjusting middle or lower layers however can create finer adjustments. This is where the support factor comes in.

If you had 2" of 20 ILD foam on the top of a mattress and you needed an extra 1/2" of cradle then a 32 ILD layer (which needed 32 lbs to compress a 4" layer by 1") would only need less than 16 lbs to compress to 1/2". It would then take @ 46 lbs (30 + 16) to compress a further 1" (1.5" total). What this means is that a 2" layer of 20 ILD over 32 ILD foam would give you the depth of cradle you needed but beyond this it would be roughly as supportive as a 46 ILD support layer. This would be the very rough equivalent of 2.5" of the same type of comfort layer over 46 ILD foam. The first example would be more progressive and the second would be more differential but would end up with roughly the same pressure relief. Of course the math here is not exact but the idea is that they would be roughly equivalent.

Another way to put this would be to use a 4" layer of 15 ILD polyfoam with a 2.5 sag factor as an example. This foam would take 15 lbs of pressure for a 50 sq inch foot to compress it by 1". It would take 2.5 x 15 or 37.5 lbs to compress it by 65% (roughly 2.6"). This means that it would take an extra 22.5 lbs to compress it the extra 1.6". So this foam would take a little more than 7 lbs to compress 1/2" (compression curves are not usually linear and the initial compression curve is generally steeper than the subsequent compression curve with deeper compression), 15 lbs to compress 1", 22 lbs to compress 1.5", 29 lbs to compress 2", 36 lbs to compress 2.5" (the middle range of compression is more linear) and about 45-50 lbs to compress 3" (the deepest compression is also not linear and starts getting firmer even faster which could be called bottoming out). This means that an area around the hips that was exerting 50 lbs per 50 sq inches of pressure could compress the top 15 ILD layer 3" but a 50 ILD lower support layer by only an extra 1". The odds are good that by the time you have sunk into the mattress this deeply that the surface area of your body that was bearing weight would be less than 50 lbs per 50 sq inches. Of course the process of how each layer reacts is along a continuous spectrum rather than in "steps" as in this example and is further influenced by the thickness of the mattress as a whole but the idea is correct.

The reason that differential is "easier" but progressive can be "more accurate" is because differential allows you to choose each layer more for a single purpose (either pressure relief or support) without taking into consideration as much how they interact or influence each other. You can choose a top layer that you know is thick and soft enough for good pressure relief without worrying as much about whether you will feel a really firm support layer underneath it. The advantage of the progressive is that you can fine tune the layering more (you're not limited by the thickness increments of the comfort layer materials). It can also use thinner comfort layers which can often allow the support layers to provide better support for multiple sleeping positions.

One other thing to bear in mind is that latex is usually tested for ILD with a 6" layer while polyfoam is tested for ILD with a 4" layer which means that the measurements don't directly translate into each other. ILD taken with a thicker layer needs more pressure to compress it 25% because the 25% thickness is more than with a thinner layer. The net effect of this is that latex ILD's will be slightly softer than the same ILD's in polyfoam.

Having said all that (and I know that this can get quite complex) you have the benefit or working with a HR foam with a higher sag factor which means that you have more flexibility when it comes to choosing layers.

Subject to knowing your "history" and "preferences" ... I would tend to start off in one of two directions depending on how "risky" you wish to be.

The first (differential) would use a 3" comfort layer which because of your lower weights and with the right firmness should give you enough thickness that you can choose a firmer support layer below it without worrying about feeling it. I would likely choose an ILD in the range of 15 - 20 (which would be a little firmer than latex in the same ILD). Under this I would put a firm 6" layer in the range of high 30's or low 40's. To save money you could also use HD foam in the support layer although HR would work a little better (because it's support factor would be higher and it would "hold up" your heavier parts better). Average ILD (assuming 15 ILD top and 40 ILD bottom) would be @32

The second approach would use the same ILD foam in the top layer but it would be thinner say 2". I would put this over a 3" "transition" layer in the high 20's to low 30's (to give you a deeper cradle but also better support once you reached the depth of cradle you needed) and then a lower layer of another 4" or so of very firm (@ 48). Average ILD (assuming 15 over 28 over 48) would be @ 34.

The unknown about either of these would be your "critical zone" which is the effective depth of cradle that is best for you and that provides enough pressure relief for your sensitivity and of course your preferences and YMMV.

14 Jan 2012 03:51
  • phoenix
  • phoenix's Avatar
Hi Fluffhead,

To me I felt as though it was not adequate in pressure relieving. I still felt a hollow feeling in my lower back or a slight aching there after a while. I don't know if my mid section sunk in to much, I don't think it did. I think it felt as though nothing was touching my lower back and I believe it was the same for my wife. I think you just wanted to know to have more information, but I do know I still preferred the F/M/n4 over it.

This highlights the difference between Talalay and Dunlop. The Dunlop would be in the range of mid 20's ILD (possibly higher depending on which side was up and how firm that particular layer was) while the N4 would be in the range of 30-34 ILD. Even though the Dunlop has a lower ILD which would normally be more pressure relieving ... because it has a higher sag factor ... it didn't seem to form as deep a cradle for you (less pressure relieving and didn't fill in the gaps as well). The fact that the n4 and the soft Dunlop are both a little on the firm side seems to indicate that n3 would be closer to your range in a 3" comfort layer. Of course F/M/M would be even worse.

On the n5/n5/n4 the position I was speaking about was actually on my back. I couldn't get over how it felt. It was almost like the back of my legs were slightly numb, not asleep though, and my muscles couldn't relax. It did not contour for me and i felt as though my midsection was being lifted up or higher than my shoulders. I do need to be careful in my description of my feelings because I am use to a bed where my mid section sinks in more.

OK ... that makes more sense. I just read my last comments as well where I said "on the previous day on your back this layering seemed too soft" but you hadn't tried this layering or even the same top 2 layers the previous day (it was the F/n4/n4 and the F/M/n4) ... so my comments relating to this part weren't valid. To correct ...

On Day 1 you tried the F/n4/n4 which was "nice" for side sleeping but seemed too soft for alignment on your back. The F/M/n4 was too firm on your side but good for the back. This would indicate that the n4 needed "help" because it is on the firm side for side sleeping and that the 30-34 talalay helped it more on your side for pressure relief but was too soft for your back alignment while the M Dunlop helped it less on your side for pressure relief but was good for back sleeping alignment. This is the classic conflict between combination sleeping. What works for one position is either too soft or firm in one layer or another for a different position.

On the next day you tried the n5/n5/n4 which was fine at first but I don't know which position it was initially fine for (side or back) and you quickly switched mattresses so I'll pass this by because you were "immediately relaxed" when you went to the F/M/n4.

When you went back to the all talalay n5/n5/n4 the lack of moving around compared to the F/n4/n4 from the previous day would be for the reasons I mentioned before (top 2 layers were firmer overall). Because the top 2 layers were firmer overall ... this would also have stopped you from sinking in as much and filling in the gaps as well as the softer n4 middle layer. Because the n4 on the top is already on the edge of too firm ... making the layer underneath it firmer as well would likely account for the numbing effect because what was already on the edge would be over the edge with a firmer n5 middle layer. The feeling that your midsection was higher than your shoulders would be unlikely but it probably was much higher than you were used to with the firmer n5 underneath. All in all ... it seems that the n5 middle in combination with a the n4 top (which is on the edge of being too firm anyway) is just too much "firmness" both for pressure relief and for filling in the gaps in your profile. It doesn't form a deep enough cradle.

So up to this point the preference is the F/M/n4 even though the pressure relief on the shoulders isn't as good as it should be.

I told my wife before we went to bed that I think the reason she liked it so much was because her body is not heavy enough to go through the n4 layer where as the n5 either stiffened up the n4 under my weight or I went through it and the n5 was too stiff underneath

This is likely very accurate. For her weight ... the n4 would be an unusually firm preference for a comfort layer and it's doubtful that she would even "go through" 3" of softer latex much less the n4. You on the other hand being larger and heavier could go through it and feel the underlying firmer layer more than her.

but I already know the two layers of n4 is not firm enough from when we tried the F/n4/n4. I really wish they carried an n3 layer. That would really narrow things down.

It was better on your side but not firm enough on your back which refers back to my previous comment. The F/M was firm enough on your back though. In theory ... you would do better with a softer top 3" for better pressure relief and then firmer underneath either n5 or the same M Dunlop for better alignment. With the softer on top you could probably get away with firmer under or at least the same. This would depend a lot on the depth of what I call your "critical zone" which is the effective thickness of the comfort/pressure relieving zone you need to fill in the gaps and relieve pressure. I suspect that even with the firmer n4 comfort layer it is still over 3". How deeply you sink in to the layer below would determine which of the middle layers (n5 or M) would be best for you with an n3 layer (or equivalent).

I think I would be okay with the springiness of all talalay if I could find a layering that felt right. I have trouble imagining the effect an n3 layer would have over the n5/n5 or if n3 would be firm enough for my wife in a 3" layer.

I think the n3 (or the equivalent in blended) would work better for both of you. I also think it would allow for either the same firmness or possibly even more firmness underneath. This could give both better pressure relief on your side and better support on your back.

M/M/S would have been another good combo for us to have tried out. Maybe that would have given the top soft just a little more contouring ability and that would have been enough.

The top 2 layers are where most of the cradling comes from so changing the bottom layer wouldn't change the cradle and the pressure relief much from the F/M/S. The support would be less though. Pressure relief comes from sinking "in" to the top layers of the mattress. Alignment and support is determined by how far your heavier parts sink "down" into the mattress. Changing the bottom layer would change support more than changing the cradle and pressure relief.

Post #3 in this thread has some options in Charlottesville and Layers would be a very good place to visit and can customize each mattress. They are a factory direct outlet that is knowledgeable and helpful and have choices that are different from what you've tried. It may also be worth trying the OMI Lago which is I believe 3.5" of n3 over 6" of n5.

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