overstuffing mattress case with foam layers
Dec 1, 2010 3:33 PM
Joined: May 22, 2008
Points: 171
i have a sleepez bed that I keep trying to soften by adding more layers of foam in the case. So I now have 4.5 layers in a case meant for 3 layers. The case still zips, but I wonder if I am compressing the foam so much that it is affecting the feel. I have talalay latex, which always felt springy to me, but I am wondering if this made it more springy? Or if this is bad for the foam? 
Re: overstuffing mattress case with foam layers
Reply #105 Dec 27, 2010 12:12 AM
Joined: May 3, 2008
Points: 827
st3v3k4hn wrote:

You should write a book on this!

 

At the very least someone should collect your posts (& other good ones) and make them "stickies" - I assume you know what that is, but if not, its a collection of posts that answer the most commonly asked questions and stay at the top of the forum all the time. People basically ask 10 questions on this forum - and those have been answered 100 times, 100 ways. Awfully hard to find the best answers without something like FAQs or stickies. Wonder if there is an admin who might do this??

Just PM Admin, there is a stickies already at the top of the page.  If he likes he posts wink
 

You asked about is the blanket enough to protect the latex, yes.  You just are protecting it from light and dirt.  When I used the Natura wool with polyester backing that was rough it ripped up my latex, so no that is not good.  Luckily that latex is no longer used, it was shredded from that backing of the topper.  You don't need a zipper case for my uses.  Maybe for yours you need or want it too look good.  But mine has a sheet over it and is not seen.  Some do it yourself people used the terry cloth zipper over 3 layers of latex and it is protected enough.

This message was modified Dec 27, 2010 by Leo3
Re: overstuffing mattress case with foam layers
Reply #106 Dec 27, 2010 12:28 AM
Joined: Oct 3, 2010
Points: 809
"Uh oh Charlie Brown's teacher is here, LOL, seriously though what the heck do you mean?  Differential?  Progressive, like bifocals, LOL.  Talk layman terms for dummies please.  Do you mean a hard as rock core, then soft?  Do you mean Firm, medium, then soft is worse to do for fine tuning?"

Differential approach means a bigger difference in ILD between the comfort layer(s) and the support layer(s). Say 3" of say 19 - 22 ILD over 6" of 36 or 40 ILD (or soft over firm)

Progressive approach means a smaller difference in ILD between the comfort layer(s) and the support layers(s) say 3" of 22 ILD over 3" of 28 ILD over 3" of 40 ILD (or soft over medium over firm)

Starting with Soft, Medium, Firm can be much more difficult to adjust because it's sort of a "compromise" of both comfort and support and trying to change the comfort ends up affecting the support as well (and vice versa) more than the other one. You can often get "more accurate" this way and change the overall "feel" of a mattress more but it can be a lot harder.

Phoenix

PS: you're a tough nut to crack ... but a great "testing ground" for what I "try to" write (laughing).

This message was modified Dec 27, 2010 by Phoenix
Re: overstuffing mattress case with foam layers
Reply #107 Dec 27, 2010 12:39 AM
Joined: May 3, 2008
Points: 827
Phoenix wrote:

Differential approach means a bigger difference in ILD between the comfort layer(s) and the support layer(s). Say 3" of say 19 - 22 ILD over 6" of 36 or 40 ILD (or soft over firm)

Progressive approach means a smaller difference in ILD between the comfort layer(s) and the support layers(s) say 3" of 22 ILD over 3" of 28 ILD over 3" of 40 ILD (or soft over medium over firm)

Starting with Soft, Medium, Firm can be much more difficult to adjust because it's sort of a "compromise" of both comfort and support and trying to change the comfort ends up affecting the support as well (and vice versa) more than the other one. You can often get "more accurate" this way and change the overall "feel" of a mattress more but it can be a lot harder.

Phoenix

PS: you're a tough nut to crack ... but a great "testing ground" for what I "try to" write (laughing).

Okay so I have a "differential" setup with my hard mattress, then soft layer top.  You are saying that is better?  I notice Sleepeze 99.999% always recommends soft, medium, firm, so that is a tougher to get comfortable from the readers posting here.  But you are saying (the last paragraph) you can often get "more accurate" this way... but it can be a lot harder.

I don't know about me being a tough nut to crack, or what that means, LOL, but I am more honest than most if I don't understand something I say so.  laugh  Maybe I am asking what some other people are thinking and not posting.

Re: overstuffing mattress case with foam layers
Reply #108 Dec 27, 2010 12:47 AM
Joined: Oct 3, 2010
Points: 809
"I don't know about me being a tough nut to crack, or what that means, LOL, but I am more honest than most if I don't understand something I say so.  laugh  Maybe I am asking what some other people are thinking and not posting."

You probably are posting what lots of people are thinking and not posting ... that's why I said you were a great testing ground. The "tough nut to crack" means you are challenging me (in a good way) to be a better combination of simple and informative and that if what I post "works" for you it will probably "work" for lots of people ... but it's tough to get there :)

Sometimes too it's important (to me at least) to go into more detail than most would want just for the few that may like to read "every technicality" or every "opinion" I may have or know about. This is what some of the old posters (dbhayes, cloud9 and quite a few others) that sadly aren't posting anymore used to do as well in the old forum and the earlier part of this one and it really helped lots of people as well ... including me. There doesn't seem to be quite as much "research based" type of posts at the moment as there once was. There's a lot of people still here from those times that still post and help a lot of people so they might have an interesting perspective on this as well. Did they all get tired or did the switch in forums really have that big an effect?

Yes ... you have a "differential" setup which is easier to get "close". The progressive setup could end up better (at least for some) but can take a lot of patience, fiddling, or "correct predictions" sometimes to get there. It might also need "non standard" layer thicknesses outside of just 2" or 3" to get to "perfection". Which one is "better" really depends on the person but in my experience getting to 80 - 90% or so is probably good enough for most and this is often easier to get to with the "differential" approach.

If Soft medium firm with maybe one layer exchange is "close enough" for someone, then they are happy. If it's not close enough, or if someone really needs something closer to "the best for them" and one layer exchange doesn't get there, then it often starts an endless series of adjustments that seem too often to "fall short". Sometimes it's because none of the choices seem to work (for usually unknown to them reasons) and sometimes it's because they just run out of patience or will and think that "nothing will work".

Phoenix

This message was modified Dec 27, 2010 by Phoenix
Re: overstuffing mattress case with foam layers
Reply #109 Dec 27, 2010 2:08 PM
Joined: May 3, 2008
Points: 827
I think many old posters quite honestly still never got it right, or they got it right and stopped posting.  There are many latex mattress people who never liked the mattress and they tried and tried and some ended up loving them.  I also think some people ending up hating them and just never post back.  Who really knows.  I think some people who have some physical pain that may never get it comfortable.  But who can say that is true for sure, we are all just assuming we know how to fix a mattress by mathematical equations (not pointing fingers) but there is just comfort factors you can not equate.  The other problem is the first night the mattress sleeps great, second night not so good, third horrible; or the other experience the first night is horrible.  Now can you really say keep trying it night after night?  How long do you experiment.  Frankly I may give up and sleep in a recliner!  I have heard that statement before.  Then you have people who can sleep on a rock, they have no problems sleeping on anything (my hubby is like that).
Re: overstuffing mattress case with foam layers
Reply #110 Dec 27, 2010 3:34 PM
Joined: Oct 3, 2010
Points: 809
"we are all just assuming we know how to fix a mattress by mathematical equations (not pointing fingers) but there is just comfort factors you can not equate."

I wish there was a mathematical formula that could be used ... it could help a lot in some cases ... but I don't know of any. Who is making these assumptions ... I'd like to find them and see if they would give me their "formula" (smiling).

I certainly agree with you though that it's really hard to "figure in" comfort factors. It's a lot more intuitive than mathematical. If they do some field testing though it's a lot easier to get a sense of what feels comfortable for them.

Having said that, I do see many times people who try to change things that have little chance for success. There are always a few (like yourself) that stick to it but unfortunately there are also lots who give up once they've made a comfort switch or two that doesn't work out. Sometimes the switch they are trying has very low odds of success and could have been "predicted". I think these are the ones who often lose hope when they don't see improvement.

Most of the old posters I was talking about weren't looking for a mattress. I meant some of the old posters that had been around for many years that seemed to stop posting when the forum changed or soon after.

Phoenix

Re: overstuffing mattress case with foam layers
Reply #111 Dec 27, 2010 8:56 PM
Joined: May 22, 2008
Points: 171
Well, essentially I am one of those old posters who never quite got things right and just gave up and quit posting. It was purely random that after 2 years I thought of trying again and got Phoenix to help out. Lucky me!

Anyway, Phoenix, here is today's trip report. I went to Seattle Mattress Co and Bedrooms and More.

 

Seattle Mattress 
 
Not all that impressed with this place. Only 1 salesperson, hard to tell how knowledgeable (but she was pushing Serta, so...). Lots of Sertas and Trumps and other very comfortable but poly foam-filled mattresses that wouldn't last. Had one brand I hadn't heard of - Therapedic - that was latex over 14 gauge pocket springs. Pretty comfortable, but I doubt it would last.
 
Their latex was all talalay. (Incidentally they claimed talalay is better because dunlop is poured and so can be wavey / inconsistent feeling). Standard is a 3" soft (19 ILD) latex wrapped in about an inch of poly/cotton, over a 6" core (either 28 or 36). All of these felt too soft to me; or rather, they felt great, but I think they would be too soft to sleep on (my hips felt like they sank in too much both on my side and on my back). I also tried the topper on an extra firm continuous coil inner spring; it was a bit firmer but essentially the same; I jack-knifed a bit too much. And that was pretty much all they had.
 
Bedrooms and More
 
I've actually been here before and I really like the store and staff. They have lots to try and seem to know alot. I know they are overpriced but frankly I like them so much and like the idea of being able to easily switch things that I might actually go thru them if I buy. I didn't actually try any latex over springs there, mostly because they had a lot of latex that I liked.
 
I did try the OMI Terra, which was great, but I think maybe a bit too soft?!?! (I expected to have trouble finding latex matresses that felt soft enough, was actually pretty shocked to find that most of them were, and if anything I worried about them being too soft.) Same for the Natura with the 4" topper; although the 2" topper was a bit too firm, so 3" seems to be about right for me. Again, shocked...
 
The only decently priced latex was Englander. I had mixed feelings about this brand but they claim that these mattresses are either custom made for them or the very top of their range. All were dunlop latex only, no other foams. They had several interesting choices:
  • Separate 6" core of medium or firm dunlop, you add toppers from their collection until you are happy. I added a soft 2" talalay + a soft wool topper which felt pretty good. Would need to play more before I bought. Advantage here is its customizable, if the 2" topper isn't enough they will exchange for 3", if the wool flattens I can just buy a new one. 
  • 5.5-7.5" latex cores wrapped in quilted latex, cotton, and/or wool. There are 3 models, with differing degrees of wrap. They claim they all will hold up well but obviously the saftest choice would be the plainest, least wrapped one. This was a "cushion firm" they also called it the 5003. This actually felt pretty decent by itself, altho I think it would be best with a similar topper to above (maybe a little less, ie could probably just use the wool topper). The advantage here is its a bit cheaper (because they sell more and because some of the topper is included in the bed). Also you can flip these, which I'm not really sure is an advantage but I'll include it anyway. Disadvantage is if the "minimal" materials in the wrapping flatten you can't replace them.
  • A model with 2 4" mattresses stacked on each other. The 2 mattresses were identical; each had a "firm" and a "soft" side, and you could change the feel by changing the way you laid out the mattresses. This was a custom design done for them, and I think its not that well proven yet, but interesting concept. 

As I said, the big shocker for me was that almost all of these latex mattresses seemed plenty soft. So I am even more confused because most of these were pretty close to what I have now.  The Englanders were ~ 6" medium dunlop with anywhere from 1-3" softer latex and other stuff on top. My bed is currently set up as 6" medium dunlop with 3" soft talalay on top. Why is my bed so much less comfortable? I really hope you can make sense of this!

One other note, I am considering getting 2 twin XL pieces instead if a standard king if I get a "flippable" model; just to make it lighter and easier to flip. I think as long as I have some sort of topper on it would be fine (like the sleepez bed). Do you agree?
 
Thanks again for all your help!
 
Steve
Re: overstuffing mattress case with foam layers
Reply #112 Dec 27, 2010 11:50 PM
Joined: Oct 3, 2010
Points: 809
I think your overall experience pretty much parallelled mine at least as far as the comparison between stores. I did talk with people at Seattlemattress that seemed to know a little more but I would choose bedroomsand more over seattlemattress as well both in terms of what they knew and what they had available.

Englander in general is a kind of tricky brand because each one of the different licensees build them differently and they will also custom manufacture for different outlets. In Washington, they are made by Tualatin sleep products in Oregon so I would think if you ever need any "accurate information" about the specific outlet or model you were looking at you could call them and hopefully they would give it to you. I came across several places where I tested Englander and each of them were different. One place even tried to tell me it had "soy latex" and got angry when I disputed this. I do believe though that the Englander at bedroomsandmore are all latex. I think that the core of these may have been firmer than yours or a single core which would go a long way to explaining why you felt a difference. Your talalay top with either a firm Dunlop underneath or 2 firm Dunlops under may feel very similar.

Dunlop is an interesting type of latex because of it's tendency to settle in manufacture. This means that a single say 6" layer can act like it is softer on top and firmer underneath. This means that it's sag factor is higher than Talalay. I think this is why you often see single core mattresses made from it because it "acts" somewhat like talalay multiple layering. This would only apply though to a single 6" core and not two 3" cores since you would have no way of knowing which side a 3" core came from and it wouldn't have the same "range" of density as a 6" core no matter which side it was. If I was going to buy a single core mattress ... it would probably be Dunlop. This may explain some of the "counterintuitive" feedback that comes from Dunlop sometimes and the differences you felt from your mattress.

Therapedic just came out of a bankruptcy and is owned by the same people that own Eclipse and Eastman house. They are apparently run by "mattress people" rather than "financial people" and they have mostly latex mattresses in their pure touch line and Kathy Ireland line but they both are not "all latex" and IMO spoil them by putting some poly on top ... even though it's not as much as others. Other than that they seem to be well made.

I think that a lot of manufacturers have put softer poly over latex both to try to manufacture to a price point and also to be able to use slightly firmer latex underneath to provide better support. It almost seems that a lot of manufacturers didn't "trust" soft latex either and only recently with the introduction of some brands that are using it and "beating" the competition are you seeing it used more widely in the top layers. I think Natura and more recently Pure Latex Bliss had a lot to do with this.

I also liked the OMI and with the way it's constructed it may have been alright for support for me (my weight is fairly evenly distributed but I need soft for my bony parts) but it was way expensive. I sure did like how it felt though. For reference the OMI is 25ILD over 35 ILD over 25 ILD and the topper is also 25 ILD. They will also customize the ILD although the convoluted topper can only use 25 (softer would not be convoluted). It is also natural talalay which would act in thicker layers as sightly more resilient. I would probably be a little worried as well with that thick a layer of 25 ILD but with the thick ticking and the ability of latex to get firmer as you sink deeper, it may have been OK for me (may have been aligned with a deeper cradle) but with our weight difference it may be a bit risky for you. It does say though that in terms of feel and ILD that it felt good to you even at 25 ILD (acting a bit softer because of the convolute).

The Natura's that I tried were great testing grounds because of the different ILD's and thicknesses of Talalay that they had on top of a Dunlop core. I learned a lot about my "critical zone" (how thick a comfort layer I need) from these. I did a lot of testing here and elsewhere laying quietly and then just "bouncing" a bit on mattresses with my hip to see if I could sense what was underneath.

I am still convinced that your "critical zone" is 3.5-4" depending on the ILD of the latex in the top 2 layers. This means that a 3" topper with the right (slightly less) ILD underneath could very well feel pretty good although I believe that from your feedback that slightly firmer support would work better for you (you would need to be on a mattress longer to really know how it was support wise).

So all in all this seemed like a good experience and it seems to confirm the direction you are going. Relatively soft over relatively firm and very firm on the bottom. Dunlop also seems to be the best latex for you in the middle and lower layers without zoning at least.

Did you get a sense of whether "all latex" would work for you in a "good" layering scheme or are you still thinking that an innerspring may work better?

Phoenix

This message was modified Dec 28, 2010 by Phoenix
Re: overstuffing mattress case with foam layers
Reply #113 Dec 28, 2010 3:33 AM
Joined: May 22, 2008
Points: 171
Phoenix wrote:

"I think that the core of these may have been firmer than yours or a single core which would go a long way to explaining why you felt a difference."

 I believe it was a single piece of medium dunlop. I just don't see how it can feel that different. One thing I am thinking about is maybe if I change the orientation of my layers it would feel more like this. Right now I have both firm sides up. Maybe it would feel more like this with both firm sides in or out?

"Dunlop is an interesting type of latex because of it's tendency to settle in manufacture. This means that a single say 6" layer can act like it is softer on top and firmer underneath."

Wouldnt this mean that the supposedly flippable Englander mattresses would naturally have a firmer side and a softer side? They certainly didn't indicate this...

"I also liked the OMI and with the way it's constructed it may have been alright for support for me (my weight is fairly evenly distributed but I need soft for my bony parts) but it was way expensive."

Yeah I agree it was nice. The salesguy said you could come real close to this using the Englander Dunlop core with a 4" topper (maybe from Natura, I forget). It was about half the price, and did feel pretty good. Again I thought maybe too soft but that was the medium core not the firm core. Again I was surprised how soft this felt, especially since it was 25 ILD...

"This seems to confirm the direction you are going. Relatively soft (talalay) over relatively firm and very firm dunlop on the bottom."

So given what I have do you have specific recommendations? I hesitate to go firmer core when I still feel like the bed is too firm in the current config (5" soft talalay over 3" medium dunlop)...

"Did you get a sense of whether "all latex" would work for you in a "good" layering scheme or are you still thinking that an innerspring may work better?"

Well, the mattresses I liked best were probably the therapedic and/or s brands filled with poly foam and small bits of memory foamsmiley. As far as latex, the latex on latex felt pretty much like the latex on springs, so yes I think all latex is probably fine.

One thing I am wondering is, I've now added/removed/left my latex layers sitting in the closet enough that I wonder if they might have gone bad, like the convo foam did. I know 2 years isnt that much but the foam is not protected and its been moved / left out a lot. Again, it just feels so different from what I felt today I wonder...

Steve

PS - one more question about testing mattresses. Say I want to put a soft topper on a core and I have a medium core and a firm core to choose from. Can I tell anything testing the cores without the topper? ie can I try to get the right support and alignment on just the core, then just add the topper that is most comfortable? Or do I need to always test them together?

Re: overstuffing mattress case with foam layers
Reply #114 Dec 28, 2010 11:26 AM
Joined: Oct 3, 2010
Points: 809
WARNING: This is going to be a long post and probably of interest only to those who want to know more "why" than "what" :)
 
COMFORT
 
There are basically 3 factors that determine the comfort of a foam layer. These are how much weight it takes to compress a foam to 25% (ILD or IFD which are basically the same), how much more weight it takes to compress a foam to 65% (called sag factor, comfort factor, or compression modulus), and the point elasticity of that foam (there is no common measurement for this that I know of although it's talked about in various places).
 
ILD @ 25% (and at 5-10%) is a big part of what determines the "feel" or "hand" of a layer but it says little by itself how soft the foam is in actual use unless you happen to be one of those that sinks into it exactly 25% and the odds of this are low. If you sink into a layer less than this it will feel softer. If you sink into it deeper it will feel firmer. This is why weight plays a major role in how soft or firm a foam "feels". This feel is not the same as pressure relief which is determined more by the next 2 factors. In other words, ILD is how soft a foam feels "with a little bit of compression".
 
Sag factor (the ratio between the weight needed to compress a foam to 25% and 65%), which could also be called "progressive resistance", plays a major role in comfort and pressure relief ... at least as much as ILD. The reason for this is it is a big part of what determines how far you will sink into a layer. With a deeper cradle, you have more surface contact between your body and the foam and this distributes your weight and creates pressure relief and comfort. The more evenly a layer distributes your weight, the "softer" it feels. Once you have sunk in to the point that the maximum surface area of your body is in contact with the foam and the largest possible surface area is bearing a proportionate part of your weight, then sinking in further has no benefit in terms of pressure relief. Talalay lets you sink in further than Dunlop and since most people sink in further than 25% into a top layer, Talalay of the same ILD will usually form a better cradle and feel softer than Dunlop. Talalay can also be made softer than Dunlop because it uses less foam in it's manufacture (It's less dense than Dunlop) and it is easier to control the firmness. I should also mention here that this lower density does not mean that it is less durable because of several internal factors in the foam itself which is outside of the scope of this post. So "sag factor" is how soft a foam feels with "more compression".
 
In very general (and not quite accurate) terms, cheap soft polyfoams have a sag factor of @ 1.5 or less. HD polyfoams have a sag factor @ 2.0. HR polyfoams have a sag factor of around 2.5 (although some are around 3). Talalay latex is also @3 so slightly higher than HR polyfoam. "Normal" Dunlop goes up to around 4. Custom formulations of Dunlop can go as high as 5. Custom formulations are determined by the raw materials used, compounds added, size, shape, and depth of the pincores, vulcanization methods and other factors.
 
Point elasticity, determines how exactly or perfectly the foam contours to your body. This also plays a major role in pressure distribution. The more exactly a foam conforms to your body, the more contact area there is between the foam and your body to distribute your weight and the better the pressure relief. In the same way, an innerspring with 2000 individual springs is more "point elastic" than an innerspring with 500 individual springs or an innerspring with 2000 springs that don't act individually. Latex in general ... and in particular NR or natural latex has very good point elasticity ... better than other types of foam (and similar to memory foam except memory foam is more point "responsive" since it isn't very elastic at all). Point elasticity (or point responsiveness) is about how small an area of a layer can act individually without affecting the surrounding area.
 
Hysteresis (time delay in a foam's return) along with elasticity are also important parts of perceived comfort or "feel" as they create resilience or "pushback" and a feeling of "liveliness" in a mattress. I'm including it here because in general terms it is about how much energy is lost between a foams compression and it's return and there is a "sweet spot" that contributes to a perception of comfort and ease of movement on a mattress. High hysteresis is part of the reason that memory foam provides such poor support.
 
 
SUPPORT
 
Support is determined by a combination of ILD (initial compression of a layer), Sag factor (deeper compression of a layer), and Resilience or "pushback" (made up of hysterisis and elasticity). The two parts of support involve "stopping the sinking in" at the correct point (using layer thickness, ILD, and sag factor) and "pushing back and holding up" the more recessed areas of the body that don't "sink in" as much (using depth of cradle and resilience). A higher sag factor which stops the heavier parts from sinking in as much is why Dunlop is considered to be "more supportive" than talalay although this is only one of the parts of what makes up support. I'm including this here because "too much" or "too little" of some of the comfort factors can lead to poor support and this is where the "tradeoffs" and choices in layering are important in mattress construction.
 
 
TRADEOFFS
 
Too little ILD, especially in combination with too low a sag factor or too much thickness in comfort layers, can result in pressure relief but they allow you to sink into a layer or "go through" a layer too easily and lead to hammocking. This is typical of the thick layers of low sag factor polyfoams that are commonly used in the top of many mattresses. Low ILD's in the comfort layers with higher resiliency and sag factors (as in low ILD Talalay) and "reasonable" thickness don't usually have this problem.
 
Too little ILD in middle and lower layers can often allow for too much sinking in to the mattress and loss of support regardless of sag factor (this is what I believe was happening to you with 2 mediums).
 
Too much resilience (very low hysteresis along with high elasticity) can also "push back" too much in certain cases where the cradle is too deep and lead to perceptual discomfort for some people. This can be especially true if you sink too far into a layer with high resilience in certain zoning schemes and the wrong parts of the body (like the lumbar) are bearing too much weight. This is also another reason that the thickness of the comfort layers are important and too thick can lead to "too much" support or "upwards pressure" on the lumbar area for some people.
 
Too high an ILD, especially in combination with a high sag factor in the comfort layers (like firmer Dunlop) can also lead to less pressure relief and discomfort as well as poor support of the recessed areas of the body. Higher ILD with slightly lower sag factors (than Dunlop) can provide a deeper cradle and more pressure relief as well as better "pushback" support to the recessed areas of the body and is part of the reason Talalay works so well in a comfort layer.
 
These are some of the "tradeoffs" involved in choices of between different materials, layer thicknesses, and construction styles (progressive or differential) in different layering schemes.
 
 
Specific to your comments or questions
 
Dunlop has a "naturally higher" sag factor than Talalay because the rubber particles tend to settle in manufacturing which means that it gets firmer faster with deeper compression than Talalay. It also uses more rubber in its construction (is denser) which also contributes to a higher sag factor. This allows a Dunlop layer with the same ILD (@ 25%) to feel almost the same as Talalay if you sink into it 25% but get firmer and provide better deep support (the kind that stops you from sinking in) if you sink into it deeper than 25%.  This natural quality of Dunlop can either be "enhanced" in production through the use of different depths and shapes of pincores (and in other ways) or it can be reduced in the same way. Different Dunlops in other words will have different sag factors but in general they will all be higher than Talalay. Even those with "compensating" production methods will generally have a firmer side and softer side but some will have less difference than others. In a single core mattress that is made of only one thicker single layer, then the greater sag factor of Dunlop with a slightly lower ILD could be better because it lets the top part of the layer (say first 2 or 3") act like softer talalay but the bottom part of the layer would act like firmer Talalay. It's like "built in layering". If a Dunlop 6" core had a softer layer over it then this would make less difference in terms of needing a "soft upper part" of a layer and then a firmer Dunlop would be more appropriate.
 
I don't know the details of exactly how the Englander Dunlop is made but it would likely have at least some difference between sides. The difference may have been "offset" to some degree in production so it may be less than other types of Dunlop latex and even if it wasn't the sides may not have enough difference that flipping it would present a major problem unless someone was really sensitive. To someone who would feel comfortable laying directly on Dunlop as a comfort layer (it doesn't come as soft as Talalay), it probably wouldn't make much difference. Even if both sides were exactly the same though, it would still have a higher sag factor than Talalay and may be more suitable as a "single core" mattress.
 
Thicker cores also have a higher sag factor than 2 cores of half the thickness because of the "order of compression" of foam layers and what I am going to call a "boundary effect" which are both way more than I want to get into in this post (I made that term up because I don't know what the actual name of it is). Enough to say that they "act softer" and "compress differently". If there was a difference in density from top to bottom of a Dunlop 6" core (which there probably is to differing degrees), then the increased sag factor of a single layer core over Talalay or over 2 half cores would be even more pronounced. I doubt that turning over the 3" layers would make a big enough difference to feel that much.
 
The 4" topper over a firm Dunlop may very well give you the "OMI feel" with better support. In general the thinner the comfort layer that gives you the best pressure relief the better. The OMI 25 would feel and act a little softer because of the convolute.
 
I think the firmness of your 5" comfort layer is coming from the 2" FBM which I don't think is soft at all based on all your feedback. 5" of soft would be too much and you would certainly not be feeling it as "too firm" if the whole 5" was soft ... especially after what you were feeling in your field testing.
 
As far as the foam in the closet, I doubt that you've destroyed or really degraded it. Maybe shortened it's life a little bit. If it looks and feels OK it probably is. I think that your experience with our testing ... taking into account the differences in your support layers and in using "unknown" layers is pretty consistent with what you felt in your field testing.
 
I think trying to test a layer just for support without the comfort layers on top would give a distorted picture as the comfort layers are part of the support "equation" and how far you sank into a support layer can be changed with comfort layers and different approaches. I think you could only get a true picture with both together. Comfort layers are more suitable to "testing by themselves".
 
In general ... considering all your feedback ... I think your tendency is to sink in too far in specific places (pelvic area) and not enough in others (shoulders) so in terms of "non zoned layering" I think that a nice soft and thick enough comfort layer (probably in the range of 20 - 24 give or take and around 3.5" - 4") over a really firm support layer is looking like the best combination (outside of double zoning if it's needed). I think that "stopping the sinking in" of your hips is probably easier (with firm support layers) than "letting your shoulders sink in enough" (soft and thick enough Talalay) and the wide difference in needs between the shoulder part and the pelvic part makes a differential approach more suitable for you. A progressive approach that let your shoulders sink in enough using part of a softer (medium) middle layer mat let your hips sink in too far into that layer (like they are with your medium Dunlops) but this would depend to some degree on it's sag factor and what was under it. If you wanted to test this I would try a 3" and a 4" soft Talalay topper over the firmest Dunlop they had (either Natura or Englander) and see how your shoulders felt with each. If the 3" is enough to let your shoulders sink in and you didn't feel pressure on shoulders or hips, then it would be better than 4 in terms of support and "stopping your hips" but it may be "just short". Beyone that zoning (softer shoulder firmer pelvic) would be the way to go.
 
I know I'm going to get some "flack" from "certain quarters" for how technical and long this post is ... but you asked ... and I did my best to answer smiley. After all you are an engineer and it is your thread lol.
 
Phoenix
This message was modified Dec 28, 2010 by Phoenix

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