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adding middle layers of foam 03 Dec 2014 02:56 #1

I was sleeping on an air mattress with 6” air bladder, 1.5” medium-firm convoluted foam, 1.5” 20 ILD Talaly + 1.5” 3lb memory foam (glued together), and a 3” pillow top. The mattress was comfy but there wasn’t enough support and I would toss and turn and wake up in pain. I thought the reason was too much softness so I tried different configurations to get closer to the air bladder. Nothing worked. That’s not to say I tried everything. One possible solution is to replace the soft foam with medium foam. But before I did that, I decided to replace the air bladder with 3” Dunlop 44 ILD and I finally got a good night’s sleep.
This tells me that the Dunlop support layer is providing better support than the air bladder. But it still feels like I need more support. Maybe that’s because there is soft latex and a pillow top on top without any medium density foam in the middle. The next step is to add an additional middle layer. I am thinking of a 1” medium layer and a 1” firm layer to place on top of the 3” extra firm layer. I can add or omit the soft 3” layer and/or 3” pillow top. Is there any reason why I should consider 3” or 2” layers instead of 1” layers for this application?

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adding middle layers of foam 03 Dec 2014 09:14 #2

Hi dastur,

Is there any reason why I should consider 3” or 2” layers instead of 1” layers for this application?


There are far too many unknowns and variables involved in the different options you are considering and your design is much too complex to be able to predict the outcome of different configurations and how they will interact with your body type and sleeping style with any certainty and the only way to know the effect of changing the layer thickness will be based on your own trial and error and experience. Of course you can always start with 1" and then add additional inches if your experience on a particular combination indicates that it would be helpful although two or three 1" layers can also "act" a little softer than the same type and ILD layers in a single layer of the same thickness so you may need to take that into account as well.

In very general terms ... changing the thickness of a middle transition layer will increase the pressure relief and secondary support of the mattress and will also change the "feel" of the transition between the top comfort layer and the bottom support layer while it will decrease the firmness of the primary support. Adding additional thickness to a mattress can also change how quickly a mattress becomes firmer with deeper compression and how well it adapts to different body types and sleeping positions (see post #14 here for more about the effect of thickness).

There is also a little more generic information about different types of layering in the " putting the layers together " section of the site, more about primary support, secondary support, and their relationship with pressure relief in post #4 here and post #2 here , and more about the some of the different specs that can affect the outcome of your design in post #2 here that may help you "imagine" the effects of different types of layering changes on the feel and performance of your mattress but in the end you will need to test them in "real life" to know the effects they will have on your specific application and design because the differences you are considering will have a different effect on different body types and sleeping styles.

Phoenix
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Last edit: by Phoenix.

adding middle layers of foam 08 Dec 2014 21:42 #3

I know this is a complex design. I can experiment until I find the right setup. But experimenting has already cost several thousands and is still be a work in progress. Latex can add thousands more to the cost of experimenting and still be a work in progress. I think I may be able to find a conventional foam solution that works well without breaking the bank. But then what? I guess I could keep replacing the conventional foam every few years and live with the chemical smell. Better option would be to use conventional foam for experimenting and then correlate it to latex for permanent use.

Hypothetical examples: 3” of LUX feels like 3” 44 ILD blended Dunlop, or 2” of HR36 feels like 1” of 32 ILD natural Talalay.

Of course these are hypothetical examples only. Question is, are there any such guidelines? I understand that the ILD numbers don't necessarily correlate well.

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Last edit: by dastur.

adding middle layers of foam 08 Dec 2014 22:42 #4

Hi dastur,

I know this is a complex design. I can experiment until I find the right setup. But experimenting has already cost several thousands and is still be a work in progress. Latex can add thousands more to the cost of experimenting and still be a work in progress. I think I may be able to find a conventional foam solution that works well without breaking the bank. But then what?


For me the answer would be then I would sleep on it. If the materials you use are high quality and durable materials that don't have a smell that you are sensitive to and the mattress is a good match for you in terms of PPP then it would be reasonable to expect that you will sleep well on it for a decade or so.

I would also read read this post and this post and this topic (about their polyfoam and sources) and this post (presumably from a past employee) before buying anything from FBM or considering them as a supplier.

Hypothetical examples: 3” of LUX feels like 3” 44 ILD blended Dunlop, or 2” of HR36 feels like 1” of 32 ILD natural Talalay.

Of course these are hypothetical examples only. Question is, are there any such guidelines? I understand that the ILD numbers don't necessarily correlate well.


No ... there aren't any such guidelines and the only way to do this is with the type of personal experience and knowledge that manufacturers gain over the years that comes with trying hundreds of different combinations of specific materials and components. There are just too many versions of each type of foam or components and too many variables involved and anyone that has designed mattresses will tell you that they are often surprised at the difference between what a mattress was "supposed to feel like" based on the specs and materials they used and what it actually felt like when they put the materials together and tested it in "real life".

ILD is only one of many specs that can affect the feel and performance of a mattress that don't correlate well between different materials or even between different versions of the same material. If you are attracted to the idea of designing and building your own mattress out of separate components and a separate cover then the first place I would start is by reading option 3 in post #15 here and the posts it links to so that you have realistic expectations and that you are comfortable with the learning curve, uncertainty, trial and error, or in some cases the higher costs that may be involved in the DIY process. While it can certainly be a rewarding project ... the best approach to a DIY mattress is a "spirit of adventure" where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).

I would also base your design on a mattress that you have tested and confirmed is a good match for you in terms of PPP (the simpler the design the better) and where the same materials are available as separate components or alternatively I would take a "bottom up" approach and start with the support layers and then gradually and incrementally choose softer layers to add on top based on your experience on your previous combination that keeps moving you gradually closer and closer with smaller and smaller incremental changes until you reach your ideal design or at least are "close enough" that any further additions wouldn't be worth the small improvement that you may achieve.

Phoenix
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Last edit: by Phoenix.

adding middle layers of foam 09 Dec 2014 11:07 #5

Phoenix wrote: While it can certainly be a rewarding project ... the best approach to a DIY mattress is a "spirit of adventure" where what you learn and the satisfaction that comes from the process itself is more important than any cost savings you may realize (which may or may not happen).
Phoenix


I bought a Sterns and Foster so-called latex mattress that felt uncomfortable after a few years. Normally, I would just get rid of it and get a new one. But this time, I bought latex and my expectations were higher so I decided to cut it open and investigate. There was a 6" core of what appears to be either blended Dunlop or 100% synthetic latex (S&F refused to disclose). On top there was 1" of latex plus 1" poly foam plus more poly foam or fiber in the cover. None of this material seemed substantial. I felt mislead that I bought a so-called latex mattress with advertised 20 years lifespan when I am sure the manufacturer knew that the poly was going to break down in a few years max. It was then that I decided to buy a modular mattress so I could know what I was getting and modify it if necessary. I accepted that it could be more expensive initially but it was worth knowing what I was doing and getting because I would be healthier and in the long run it may even save money. So my next step was to go modular, which was great. But the mistake was to go with an air mattress thinking that I could dial it in. Great marketing, but not so good results. I found that the air does not support but rather just gives out.

Phoenix wrote: I would take a "bottom up" approach and start with the support layers and then gradually and incrementally choose softer layers to add on top based on your experience on your previous combination that keeps moving you gradually closer and closer with smaller and smaller incremental changes until you reach your ideal design or at least are "close enough" that any further additions wouldn't be worth the small improvement that you may achieve.
Phoenix


That is exactly what I did. I replaced the air bladder with the 6" latex core that I removed from the S&F mattress. I am not using any of the other layers that came with the air mattress because they are too flimsy IMO. I am now building on top of the 6" latex core incrementally. But I have kept the pillow top so it is better stated that I am building from the bottom and top and adding to the middle. Perhaps the better approach is completely bottom up and eliminate the the pillow top for now.

Question: I understand that synthetic latex can harden quicker. If this 6" latex core is 100% synthetic, what is the life span realistically, not just spec-wise? It certainly feels harder than 44 ILD 100% natural Dunlop. The problem is that I don't know what I don't know and I hesitate to burn through money when I can learn from someone else's experience.

Thanks!

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Last edit: by dastur.

adding middle layers of foam 09 Dec 2014 15:49 #6

Hi dastur,

On top there was 1" of latex plus 1" poly foam plus more poly foam or fiber in the cover. None of this material seemed substantial. I felt mislead that I bought a so-called latex mattress with advertised 20 years lifespan when I am sure the manufacturer knew that the poly was going to break down in a few years max.


Unfortunately this is far too common with many of the "so called" latex mattresses that are sold by the major manufacturers. Several of the forum members have done "mattress surgery" on these types of mattresses (see post #2 here ) and removed the lower quality materials and replaced them with latex (or other higher quality materials) similar to what you are doing and ended up with a better mattress than they started with.

So my next step was to go modular, which was great. But the mistake was to go with an air mattress thinking that I could dial it in. Great marketing, but not so good results. I found that the air does not support but rather just gives out.


I certainly agree with this. You can see my thoughts about airbeds in this article .

But I have kept the pillow top so it is better stated that I am building from the bottom and top and adding to the middle. Perhaps the better approach is completely bottom up and eliminate the the pillow top for now.


The pillowtop most likely contains lower density polyfoam and polyester fiber which could be a weak link in a mattress no matter what you use underneath it. You could use it as a temporary topper on your mattress while you were deciding on additional layers to add so that your mattress was a little more comfortable but it probably wouldn't be the best idea to use it on a more permanent basis.

Question: I understand that synthetic latex can harden quicker. If this 6" latex core is 100% synthetic, what is the life span realistically, not just spec-wise? It certainly feels harder than 44 ILD 100% natural Dunlop. The problem is that I don't know what I don't know and I hesitate to burn through money when I can learn from someone else's experience.


I don't know all the specifics of the latex core that they used but I believe it was synthetic latex or mostly synthetic latex in either a C4 or C5 range made by Mountaintop foam. It's not possible to attach a number of years to the durability of a mattress component because there are too many variables involved and durability is always relative to a specific person (see post #4 here ). Some of the variables include the layers above it, the body type and sleeping position of the person, and how sensitive they are to foam softening or impressions before they are outside the comfort or support range that is suitable for them (see post #2 here ). A mattress that is "on the edge" of being too soft for a specific person when it is new and that goes through even a normal break in period may cross the threshold and become too soft for someone that is sensitive in a matter of months but for someone else where the same mattress is more inside the comfort and support range that is suitable for them or that is less sensitive to foam softening, the same mattress (and the materials and components inside it) may last for a decade.

Synthetic latex in the softer or medium ranges is a durable material but in the firmest ranges it would generally be less durable and be more subject to impressions than firm latex that had a higher natural rubber content. Having said that ... the weakest link of a mattress is generally in the upper layers not in the support materials so while your core may be less durable than other types of latex, it would still be a more durable material than other types of foam. I would test it on the floor to see if there are any soft spots or impressions that are obvious and if it's still in good condition and has no significant impressions or soft spots then in a typical mattress construction with comfort layers on top it that are a good match for you in terms of PPP it would be reasonable to expect that it would have years of life left in it and if it ever does become an issue then you can replace it when and if that becomes necessary based on your actual sleeping experience.

Phoenix
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Last edit: by Phoenix.
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