Mattress Forum

[QUOTE:]

This is where choices come in to use mainly upper layers for conforming pressure relief (softer/thicker with firmer under) or using upper layers and the top part of the middle layers for conforming pressure relief (softer/thinner with slightly less firm under). The first method leads to less (non pressure relieving) sinking in of the heavier "bony prominences" in the deeper layers if necessary for alignment. The second method leads to more (non pressure relieving) sinking in of the heavier "bony prominences" in the deeper layers if necessary for alignment. In either case the pressure relief can be the same, what changes is the alignment that gives the pressure relief.

So it seems like for most people you can have 3-4" of comfort material over 3-4" of support material. So why do most mattresses have 3 or even 4 layers (9-12"). Do the 3rd and 4th layers really do anything? There is obviously less compression the deeper you go, how different is 2 layers (say 22 over 28) on wood vs those same 2 layers on a firm core (say 40 ILD) or over another soft 22 layer (like you have)?

OK OK... but it wont have any reasons why

"You can control pressure issues by creating a deep enough cradle to spread out the weight (lowering psi pressure on different parts of the body) and the different methods of doing this are how you control alignment at the same time".

Does that work?

Phoenix

Much, much better Phoenix; but HOW do you control the pressure issues by creating a deep enough cradle?   My husband sounds just like you, LOL.  I have to tell him (nicely of course) you take too long too explain something, just TELL ME!

The trick is figuring out what density (ILD) to put on the top layer over the underlying layer (bla bla bla)........  Just TELL ME!
 

If you had someone that didn't like sinking in and they were fine in terms of pressure relief with a 1" or 2" layer on top and firmer underneath, they may not sink in quite as far as they need to for alignment. In this case you could put a softer 1 or 2" layer under a firmer layer to create alignment without affecting how far they sank into the upper layers (their cradle). Subjective feel can play a really big part in how someone likes their mattress and in some cases it can even affect their perception of pressure or alignment. If a softer layer is under a firmer one, it will start to compress "first" before the one above it (this is not black and white as the very top of the firmer layer would compress first) and it can change how the bed responds and feels quite dramatically in some cases without directly affecting pressure relief.

All of this is not quite so "black and white" of course since some layers ... especially in the middle ... play multiple roles but in general you need thicker support layers than comfort layers. Thicker layers also have more "flexibility" as they have a bigger "range" of useful responses. For example 4" firm under 2" soft may work well for someone in most of their sleeping positions but may not "have enough left" to deal with say side sleeping or unusual positions or movement. 2-3" in the comfort layer is "typical" and that with one or more support layers totalling around 6" is usually fine to accomplish what most people need. Beyond this you are usually dealing with either "feel" or unusual issues.

Mattresses in general are usually thicker than they need to be. The Europeans have "figured this out" more than North Americans.

Phoenix

PS: I should add that my mattress was 2 sided so it would always add up to being thicker than a 1 sided mattress. If I had gone one sided it would have been much different and thinner.

LOL. If we take this back to the other thread then I can "hopefully" make a few suggestions without "confusing" things here (I get confused REALLY easily with "multiple" threads :)). Part of the difficulty is that it's not just ILD but layer thickness and "interaction" that makes a difference and we have to do the "best we can" with the layers you have. Can you let me know what is happening with your current configuration?

Phoenix

What would you have done if you went 1-sided? Just curious...

I was bothered last nite by a lump in the middle of the mattress and so I opened it up and sure enough the convo foam had bunched up inside the cover. So I decided to take it out (reducing foam compression even more, hoping to make it a little softer) and, upon inspection, I can see that it is compressing where we sleep, and firmer/higher in the middle and on the edges. I wasn't really sure what to do so I zipped the mattress cover with just the sleepez foam in it and put the convo foam on top. Then, since I don't have a cover for it, and to maybe hide the unevenness a bit, I put my thin (1") wool topper over it. So thats how it is right now, but I can still see and feel the compressions in the convo foam. And I still don't know if it feels soft enough (definitely not near that pillow top experience)...

With the convo and the soft Talalay on the floor, you noticed hip and butt pressure ... different from the "norm". Your shoulders "seemed" ok (for the short time you were on it)

With the same convo and soft Talalay on the firmest Dunlop setup we could manage, the pressure issues had shifted to your shoulders.

In the first  one, the floor "stopped" your lower body cold but probably made no difference in how far your shoulders sank in so you were probably in better alignment ... even though this alignment caused hip issues.

In the second one, you were able to sink in with your hips enough that there wasn't the same pressure there but this probably caused you to sink in too far and put you out of alignment. This could create a perception of too much pressure on your shoulders (they "wanted" to sink in more to keep up with the hips but couldn't). It seems to me that the shoulder pressure is a phenomenon you feel that is "relative" to the hips.

This difference between the two constructions is telling me what I suspected which is "too firm" on top and "too soft" underneath. More the too soft underneath part.

There are a couple of "consructions" using what you have that may alter this a bit ... whether they get to "perfection" or not I don't know.

The first option is to put the soft Talalay over the convo over one layer of Dunlop (convo under the talalay so it doesn't bunch up with direct pressure and stays more even). This would give us something "in between" the floor and what you have now but it would only be 7.5" and wouldn't fill your case (calling the convo 1.5). This would give you the "firmest" support layer that was possible without killing your hips on a floor.

It would also be worthwhile if you are changing layers to do a "floor" experiment with soft Talalay over medium dunlop. Surprisingly this could work better than what it may seem although it may be a little on the thin side (you would have most of the talalay and a bit of the dunlop which would be "acting" soft). I would use the Dunlop label up (hopefully soft side) for this one.

The second option would be to use the memory foam under the 3" soft talalay over the firm dunlop. This would also be "thin" and I'm not sure how the memory foam would react with this much on top of it. I suspect it would start off a little firm feeling but would slowly "soften" as you lay on it longer. It would probably depend on the type of memory foam and your experience with this would say more than any "theory" about what it might do. A "floor" experiment with this wouldn't help as much because the memory foam would take some time to get to it's final "softness".

If either of these improved the situation, then it would be a matter of finding something to "fill up" your case that didn't let you sink in.

The other options after this would be about changing the feel using what was on top (wool, cuddle bed etc). If this next step was to help with the shoulders, then the feel could be "adjusted" using what was on top.

At least it seems we know how to "shift" the issues from your shoulders to your hips and I believe we have a much clearer "handle" on what is probably happening.

Phoenix

The first thing it would have changed was the "cushiness" of my quilting. The only reason I felt sort of "safe" using it was because flipping the mattress can help with the depressions that would likely develop over time using this. The material used (quiltable latex and the "down alternative") are more resistant to compression sets than most but it could still be an issue over time. I really liked the feel of constructions like this in my field testing which is why I wanted to include it in spite of the risk. I do like to "sink in" a bit but not into "sand".

So without that the rest would change a bit as well. I would likely have used a similar comfort layer perhaps slightly softer and the same thickness. I would have used a firmer middle layer (probably around 32 and perhaps even more) and probably as firm a bottom layer as I could. I would also have seriously considered a 6" firmer core (not 2 x 3" layers) under the 3" comfort layer. I would have been trying for "good alignment" with less sinking in and a less "cushy" feel.

Phoenix

I've been gone all day and so I won't have time to try the configs you mentioned. But some more data. The bed with the convo foam and wool topper over the mattress was way too firm, hardly slept at all. Finally removed the wool topper at like 4 am and I think that felt pretty good, got a few hours sleep at least. Will try again tonite. The convo foam over the mattress (as a topper) definitely felt softer to me than the convo foam in the mattress...