Mattress Forum

I resonate with your question. Unfortunately I cannot help specifically, but I'll share what little I've been learning. I ran across an interesting article yesterday that provides atleast a relative understanding of how different mattress toppers might compare. see the following link: http://www.beddingcomponents.com/pdf/innersprings/softech-chart.pdf

I'm aware that most manufacturers evaluate warranty claims by how much change there is in the height of the bed where it has broken down the most. For foam type mattresses the standard threshold appears to be 3/4 of an inch of dip compared to a string held taught from the head of the bed to the toe. (I'm told they just use a short length of 3/4 in diameter PVC pipe.) For innerspring mattresses the standard is typically 1.5 inches.  Unfortunately however, the height to which the foam springs back has no direct bearing on the firmness of the mattress that is lost over time. Honestly I think their warranties should be based on both factors: loss of height, and loss of firmness. In your case, you could measure how much dip your bed and topper have together and use the same 3/4 in or 1.5 inch criteria as the big mattress companies. Otherwise, my only thought would be an anecdotal retrospective evaluation of your overall sleep quality: if you start waking up with an aching back or neck that's not likely caused by something else--then try a new mattress. That's all I have for you, sorry it's not more. The rest below is really just a rant

Somewhat related to your question, I'm finding it generally pretty tough to get ANY actual scientific numbers on the height and/or firmness retention of the various bedding materials commonly used. It's really frustrating to me to be looking at mattresses in an industry where the most information on I can get on a particular product are the Lbs/sq.ft. densities of the foams, or maybe the gauge of the wire springs. I'm appalled at how little scientific information is available to the end user.  

I work in a medical diagnostic device research and development company that has to have very clear specifications on materials and nearly all related characteristics. I'm somewhat used to reviewing material spec sheets for things like thermal stability, durometer, crushability, puncture resistance, water-vapor-transmission rates, UV stability, off-gassing, chemical inertness, Bio-compatibility, microbiological compatibility, surface binding potentials, etc. etc. There's a lot of marketing out there that claims that Company A has spent more on research than Company B, or that they have the most "advanced technology."  Those terms seem to imply that they are familiar with the concept of the scientific method that was pioneered several centuries ago that ushered in the enlightenment era that led to the industrial revolution.  In spite of that implication however, these mattresses are sold as anecdotally as snake oil used to be sold as a “cure-all” a century or two ago.

How often have you heard a salesperson say something like: "I've been in the mattress business for (a good number) of years... and this is the one I sleep on at home." My response to that is, "Yeah, so. We all wear different sized shoes and pants too." Or they’ll tell you things like: "Well, my friend had that other brand and they had big problems with it."  (I wonder what kind of problems their customers are really having with their mattresses that they are not telling us.)  But really, though, is an anecdote about some 3^rd or 4^th party’s dissatisfaction a compelling reason to spend several thousands more than you would otherwise?

They all ask, "how does this one feel to you?" But aside from how I'm feeling at that second, there's no real evaluation of my actual posture, physical alignment, weight distribution, etc.  After working in an emergency department at a major regional hospital for several years I can tell you that people RARELY ever actually lay straight when asked. On their own they "feel straight," but their feet hips and back may be 3inches out of alignment. They might realize however that they weren't actually straight once you straighten them up.  Consider this, if a radiology department can't rely on people to lay straight (even if they have perfect lateral symmetry) for a simple skeletal picture that a physician looks at for a few moments to spot gross pathologies, what makes mattress salesmen think that people can reliably discern when their posture is good/correct on a bed?  If it takes a physical therapist, an orthopedist, and a prosthetitician to correctly fit orthotics, prosthetics, or even simple old-fashioned crutches, why don't we have Sleep Posture Therapists that can truely evaluate one's posture and fit the right bed to your body type..with real knowledge, real numbers, and true ergonomics?  Hmmm...maybe there's a niche theraputic market there?  

One thing I really don't like about the typical box spring these days is there tendency to sag if the center slat is not supported which I think is often the case in twins, fulls and kings.  I'll explain why -

Typical box spring has a pretty simple construction - at bottom, a perimeter of wood slats with a center slat from head to toe.  Then there's about 7 cross slats that are supported by the center slat.  The cross slats support vertical rods that go up to the surface.  So, when laying in center of your area, it presses onto the cross slats and center slat and the greatest weight is in hips and butt area of it all.  So, that center slat flexes and bows downwards.  Only way to prevent that is if you have a frame center rail that fully supports that center slat. ...

but, King frames don't have a center support for each twin box spring.  Twin and full frames I think usually don't have a center support.  Whatever the frame situation is, I think the center slat must have full support.
 

interesting... I wonder if we need to investigate putting something under it to help support it... I'll ask my husband to look underneath sometime while I am laying in the bed and then do the same for him. Do you think we'd be able to see any difference from the outside?

Does anyone else have any thoughts on the lifespan of memory foam toppers?

Thanks
 

http://elderrubber.com/material.htm

These guys have some good specific information regarding different polymers, AU (polyurethane), SBR (synthetic latex), NR (Natural Rubber).  I would not count on the industry providing good scientific information.  What we do have are gimmicky presentations designed to appear scientific but in reality have no basis on the facts.  Things like pressure mapping comparing memory foam to talalay latex or dunlop latex when the ILD's are not listed.  Comparing breathability of talalay latex to dunlop latex made without the pincushion structure to it.  Claims that state latex foam is more durable to a spring system by saying the springs lost more height when the tests performed do not simulate real life scenarios and we have no idea what the spring design is or any of the specs on it.  Durability tests on foam that only use roller beaters to crush the foam repeatedly but without the real life exposure to long term humidity, ozone and salt damage that all have a big bearing on how long foam's last.  

We have a LONG way's to go before we get credible, relevant information from mattress manufacturers in general.

Apparently their homes consist of wall to wall beds, because it seems they personally sleep on every single mattress that a customer expresses interest in.

Wow - that really is an interesting link. Correct me if I'm wrong but is that a topper made of pocketed coils? First time I've seen that!

This quote was interesting -- considering it was their change in their products that led to the "ubiquitous" problem beds have with impressions.

"Low-profile innersprings are helping mattress makers battle the ubiquitous body impression problem and springs suppliers proudly extol the virtues of their product in preventing this cause of so many mattress returns.

“We are all charged with making sure our mattress products don’t come back due to body impressions,”

I've said it before and here it is again - nothing was easier on my right shoulder than memory foam.  The all latex had good support for sure, but pressing down on it, I could feel the immediate response and resilient pushback.  It was fairly easy on my left side, but too much pressure on my right.  I suppose most people without a bad joint can sleep on all latex.  If I were to decide against the TP, I would go back to the all latex and stick with it, but I doubt that will happen.   btw, it was 80 F in my room at 11pm and I didn't have a temp problem sleeping in the TP.

I should add that even with our new latex foam (from FBM -- need to start another post on that!) the bed is still a bit firmer in the very center. I don't know if that's because it's the area with the least wear (ie we tend to sleep on our own sides) or if it's from the support of the center rail on the metal bed frame between our split box springs.

Think I said this above, but I've found that all mattresses break in where you sleep and are softer in that area.  Even the Tempurpedic Cloud, however, if I lay near the edge of it, I'm securely in place.

Should you put a piece of wood to support the center slat?  I don't know.  Sounds like a pain to do.