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I have searched the forums without much luck, so I am posting my question here. About a year ago we purchased a split king from SleepEZ. My side has a Talalay soft layer and Dunlop medium and firm layers. When I sleep on the mattress my mid to upper back gets so painful that it wakes me in the night and it tends to be painful the entire next day. I have tried all possible combinations and permutations of the layers with little relief. (I have the same problem on my wifes side of the bed) I have tried thick pillows, soft pillows, two pillows etc. I have also tried different toppers I do tend to end up on my side, occasionally on my stomach... I sleep fine on the guest room traditional mattress or in a recliner. We are going to have to get rid of the bed if we cannot come up with a solution... Any thoughts? Thanks jms This message was modified Feb 26, 2010 by jms969
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Density can be a measure of durability (longevity) ... but only if you are comparing the same material. 3 lb memory foam will usually not usually last as long as 5 lb memory foam (of the same type). 1.8 lb HD foam will not last as long as 2.5 lb HD foam (again of the same type). Notice here that anything in a poly foam above 1.8 is usually called HD (High Density) while in other foams (memory foam for example) this would be ridiculously low. HR foam means high resiliency which means it can be compressed and come back more readily and more often (not as prone to holding an impression). It is generally considered to be the best of the poly foams. There is a lot of research going on to make HR foam with qualities and durability that mimics other foams (latex for example) or that has certain desireable qualities. Also ... if you are comparing the same materials, a higher density will have a higher ILD (measuring the initial weight it takes to compress a foam down 25%). Typically these measurements are done on a piece of foam 4" thick and at least 20" x 20" and the force is applied with a round 50 sq in deflector foot. Different foam thicknesses, sizes, and percentage compressions as well as many other factors will lead to different numbers so this is the "sort of" standard but it is not completely definitive. A really great discussion of this and the huge number of variables that can be involved in ILD (for those so inclined) is here (the pfa or polyurethane foam association is a great resource) http://www.pfa.org/jifsg/jifsgs4.html ILD and IFD are the same thing with a different name. Support factor (also called support ratio or compression modulus or comfort factor) is discussed here http://www.pfa.org/intouch/new_pdf/lr_IntouchV3.1.pdf I'm glad you asked this too because I just realized that the support factor is a ratio between 65% and 25% and not 75% and 25% as I have been saying earlier. There are some sites that talk about it as 75/25 but the pfa is the "authority" so I have learned something today that I never noticed before lol.
Anyway back to your question, when you are comparing different materials, density does not have nearly as much value and really doesn't say much at all about either comfort or support. For example a 3 lb HR foam will usually last for a very long time and is considered very dense and firm while a 3 lb memory foam will usually wear out (or lose it's properties) much more quickly and is considered very soft. Both memory foam and latex are common in around the 5 lb range and yet the latex is much longer lasting and offers much more support. So density only really says how much a cubic foot of material weighs and little about the qualities of the material itself.
Density is only really good as an indication of the relative durability and longevity (and in most cases firmness) of 2 pieces of foam of the same material
As to your last question ... When I'm interested in something I read a LOT. I tend to be a "researcher" by nature and enjoy the challenge of getting to the bottom of things. Sometimes getting to the bottom means falling into a never ending pit though (laughing). Phoenix This message was modified Oct 12, 2010 by Phoenix
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Thanks for the info. Within the PU family, it does look like support factor is positively correlated with density. That makes sense. Do you have a reference chart that shows support factors for a lot of different types of foam? Latex vs. various PU vs. memory foam etc.? Of course it will vary from product to product, manufacture to manufacturer, etc. But would be nice to have a general guide. |
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I sure wish I did but I've never found one. Support factor doesn't seem to be discussed as much and while there are quite a few places that talk about the ILD of different foams, support factor information, as important as it is, is a lot harder to come by. I think that the foam manufacturers (and bed manufacturers as well) often keep crucial information to themselves or tend to talk about their foams in more general ways in an effort to delay others from duplicating it. I'm still looking and in the end may have to put my own chart together from many little pieces. Phoenix |
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Phoenix wrote: "I think latex is the issue"
Not so much the material itself but the support it gives in the softer ILD's very well could be. An HR poly foam with the same qualities (ILD and support ratio) would have the same issues. From everything I know and based on the people I've talked to that know a lot more than me, back issues have very little to do with firmness or softness per se ... even though it's a common misperception. It has much more to do with how well the back is aligned when you are sleeping and misalignment ... and back issues ... can happen with any firmness of mattress. I have had the exact same issues as OP with latex not working for me in any configuration, and could not empathize more. Not a great feeling to have a mattress that creates pain, when it should provide rest and shelter - and to start getting mad at it! |
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"Yes, but the firmness/softness of the mattress can impact body alignment, at least in my experience." Couldn't agree more |
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To be clear - I think latex at any firmness can cause back problems for certain people, myself included - with the compression/"pushback" that feels like something is searing into one's pressure points. Separately, I think mattress firmness level - whatever the material, latex or cotton/innerspring or whatever - can impact alignment. So i was making two separate points in my post and not meaning to conflate the two. BTW, wish someone could do a more scientific study of the two camps of love vs. detest latex, and try to find patterns systematically across size/weight, body type/weight distribution, level of athleticism (fat/muscle ratio), any existing back problems like scoliosis, how one sleeps, etc. My guess is that patterns will emerge, since there are such extreme experiences in each camp (hence the love vs. detest). I really wanted to love latex for a number of reasons, and would never have guessed that it wouldn't work for me, especially as I'd never had problems with beds or sleeping before. My first stint on a latex bed about a year ago started my long (and yet to be resolved) saga with beds and back pain. Without being overly dramatic, my bed sometimes feels like a torture chamber. And when else do you voluntarily retire to pain every night? |
| I have found that elevating the head end of my latex mattress helps my back quite a bit. So far. Maybe I need an adjustable bed. I, too, had some trouble adjusting, but I doubt it's the latex for me because I have varying degrees of pain no matter where I sleep. |