DIY Mattress design theories - when to put a firm layer on top of soft layer?

I’m trying to design a 3 layer latex split king mattress.

My husband and I are going to try to narrow down our firmness preferences this weekend. I’m going to have a number of different configuration options to test out.

I know that typical mattress designs put the firmest layer on the bottom, and then it gets softer for the middle/transition and comfort layers.

I’m wondering if there’s some known situations where one would design a mattress with a firmer layer on top of a softer core?

For example, I can test out:

Top Soft
Middle Medium
Bottom Firm

Top Firm
Middle Soft
Bottom Medium

Top Soft
Middle Firm
Bottom Medium

etc.

I’m the person who posted a while back about wanting to avoid a quicksand feel, and being able to change positions easily while sleeping. Would that be a situation to try a firmer top layer over a softer transition?

Having a soft bottom support layer seems somewhat pointless, or is it?

There must be some basic physics principles that apply to the order of the layers, heh, but I forget most of my physics knowledge from school days.

Hi amnj,

This is great, as the only way to know whether any specific mattress design or combination of layers and components is a good “match” for you in terms of comfort, firmness, and PPP with any certainty will be based on your own careful testing and/or your own personal experience when you sleep on it. It’s nice that you have the option of testing out these configurations in person.

Yes, you are correct, this is the most traditional design, what I term a more “progressive design”.

Certainly, it is quite common for people to do this, for example a design of, top to bottom, Medium, Plush, Firm in the configuration you’re considering. It generally provides a bit less of a “point elastic” surface comfort, but as long as the top layer isn’t too firm or thick so that it totally dominates the layer beneath it, it can provide a sleeping surface that is a bit less “mushy” and tends to feel a bit more “crisp”, which is what I think you are trying to achieve (or at least avoid the quicksand feeling). You can read more about this in post #33 here and the posts it links to.

If you’re curious, there is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”. You always want to make sure you have good support and cater to overall alignment.

It is a less common way to soften up a mattress, but it can provide a bit of overall extra plushness to a mattress that has already been completed when the desire is for just a bit of extra softness with as little disturbance of the feel in the uppermost layers of a mattress. I remember this configuration was applied in the short-lived Pure Latex Bliss Prestige line in their St. Honore beds, but these were essentially already finished 11" mattresses with 2" of softer latex placed at the bottom of their configuration. In a 9" latex mattress using three 3" individual layers, using a plush lower 3" layer isn’t something that I would normally recommend and is not commonly pursued.

Even if your knowledge of physics was still fresh, trying to predict the feel of a mattress and completely describe the interactions of multiple layers, what I call “theory at a distance” is incredibly complex and even experts in mattress design with decades of experience are often surprised at the feel of their creations. There is as much art as there is science in creating a mattress. Having said that … you can see some general comments about the properties of an “ideal” mattress in post #4 here.

Let us know if you find a configuration that you like after your shopping visit.

Phoenix

It’s been over six months since my last post here.

Over the entire month of December through beginning of January, my husband and I tested out different configurations of latex layers. None of them worked well enough for us! I got so frustrated that we returned almost all the layers we’d purchased, packed up our testing bedframe into the closet, and I haven’t been able to revisit our DIY mattress project until now.

Looking at my notes for what we tested, we talked about variations of the usual progressive design, for instance:
Top 2" N3 Talalay, Middle 3" 75kg/m3, Bottom 3" 95kg/m3
It turned out that such a hard bottom core layer was problematic for us so we had to start over with our design plan. But nothing felt right until one night I decided to put one of our potential core 3" layers on top. It turned out to be the least bad of configurations:
Top 3" 75kg/m3, Middle 3" 65kg/m3, Bottom 3" 80kg/m3
This is why I’m now continuing this thread where we’d discussed the theory of putting a firmer layer on top of a softer layer.

I need help brainstorming testing options. I feel very confused now about what might work. Here’s a list of what we tested and the result. For simplicity I’m using density#s in kg/m3 and there was one Talalay layer we had to work with that I labeled N3 (the Latex Intl firmness designation for approx medium). Our original plan was an 8" mattress design with two 3" layers as the core, plus a 2" comfort layer.

  • 2" N3, 75, 85 = Too hard, lower back pain no lumbar support
  • 2" N3, 75, 80 = Too mushy/quicksand feeling
  • 2" 65, 75, 80 = Hip flexor soreness similar to when sitting too long, too soft?
    [li]2" 65, 65, 75 = Too mushy/quicksand feeling[/li][/ul]
    Gave up on progressive design
  • 3" 75, 65, 80 = Slightly too hard, lower back pain no lumbar support + husband had neck/shoulder soreness; but this is very close
  • 2" N3, 65, 80 = Hip flexor soreness similar to when sitting too long, too soft?

Typing this out I’m remembering that I had an idea to try 2" of 75kg/m3 with 1" of N2 Talalay on top to see if that helped fill in that lumbar gap. I also remember wondering if our planned wool mattress protector (St Dormier) would be enough cushion to provide the needed lumbar support. I didn’t order the protector yet. Could 1" of cushioning (Talalay or wool) even help enough with lumbar support? I know some vendors don’t even sell 1" toppers because they believe it doesn’t do much for you if you have less than 2".

I feel very torn about Talalay vs Dunlop on top because I love the feeling of how Talalay relieves pressure but at the same time think that it contributes to that dreaded quicksand feeling and having a hard time changing positions. I thought that the N3 Talalay would have a very similar firmness to the 75kg/m3 Dunlop, so it was surprising to me that it seemed to be too soft when the 75 Dunlop seemed too hard. Am I correct in thinking that if I’m waking up with hip flexor soreness that means my hips are sinking in too far so my body is no longer lying straight but is instead in a slightly bent/seated position? Do I need to move up to a N4 Talalay firmness?

Then for Dunlop there is one density I haven’t tested and that’s the 70kg/m3. I also considered going up to a 10" mattress design by doing the 6" core plus two 2" layers on top, which opens up a giant can of worms as far as possibilities. Sigh.

Anyway, like I said earlier, I am quite confused.

As an aside, but related question, I’ve found a lot of places who sell Dunlop toppers that can be returned, but I can’t seem to find many places who sell Talalay toppers that can be returned. Also, many companies have a policy where a customer can only return one item every twelve months, so I don’t think I can order any more latex to try out from any of the places I ordered before. (Rules out SleepEZ, SleepOnLatex, LatexMattressFactory) Any suggestions for somewhere else that allows returns of toppers and carries Talalay toppers?

Hi amnj,

I’m doubting that there is an actual “gap” in your lumbar region with the configurations you’re describing. And I don’t think that what you’re describing as a lack of lumbar support is necessarily that. This would be you sinking in as if you were in a hammock, but you even state that with a firmer layer on top you had “no lumbar support”, so you are obviously describing a bit of a different sensation here, but I can’t “feel what you feel” so this description leaves me a little puzzled as to what you’re attempting to convey. Perhaps that things don’t feel “substantial enough” under your lumbar region?

I wouldn’t know if the configuration with the extra 1" of latex you’re thinking of trying out would work or not – that can only be determined through your own careful personal testing. I can tell from what you’ve been describing that the only configuration that moved you closer to comfort was with a firmer layer on top, and it is common that people choose too soft upper comfort layers and you may have specific needs for something more substantial in the uppermost layer. Plus, you’ve mentioned numerous times you don’t like a squishy feel on top of the mattress.

If you like the more buoyant feel of Talalay latex, you may wish to try a Talalay topper in the upper 20s/lower 30s ILD range.

I can’t diagnose what may be causing your hip pain on an online forum. You could be pressure sensitive in your hip area because you are sinking in too much. You could be pressure sensitive because you are sinking in too little and the surface area is too hard (this doesn’t seem to be the case). It could be an issue that you are not very flexible in either your hip flexors or your iliotibial band, and this combined with sinking in too much could be an issue when the two add together to the problem. I also have no idea how long you’ve tried each configuration to give your body a chance to adjust and lose some of its “false firmness”.

I wouldn’t go softer on top, as you had a positive result moving to a firmer upper layer. And if you’re complaining about “no lumbar support” it doesn’t necessarily make sense to soften up the upper layers.

You may wish to try a firmer Talalay on top, and perhaps the medium Dunlop beneath that to provide a more supportive transition layer. And whatever configuration you test, give it at least two weeks before changing, as it will take some time for your body to adjust. You can be surprised as to what feels too firm in one week becomes more comfortable in the second week as your body adapts. All of this is part of the trial an error of creating your own DIY mattress. Hopefully some of this information helps you out and points you in a better direction.

As far as topper that can be returned, here is a list of a few of which I am aware.

Phoenix

Thanks for your thoughts on this.

I think you’re right that my use of the phrase no lumbar support might not be the right description. What I’m feeling is the same sensation as lying on the hard floor, for instance like a yoga mat on hardwood floor. In that situation my back tends to sway back too much which creates a gap under my waist.

With the configs that I believed to feel too firm, I begin the night feeling very comfortable but by the middle of the night to morning I start having lower back pain that can only be relieved by lifting up my knees to straighten the lower spine. I think I also tried putting a thin cushion under my lower hip and that helped correct the spine position. I just felt like I ended up sleeping in a backbend position which was super uncomfortable for my lower back.

Then with the configs where I felt the hip flexor soreness, I think those were too hammock like for me, so I wasn’t lying straight enough for the front of my hips to get proper rest?

Does all this still point to probably needing a firmer layer on top?

Hi amnj,

Are you describing sleeping upon your side or back?

Phoenix

Sleeping on my back.

I used to be a combination side + back sleeper, but I think because of my terrible almost 10-yr old Serta continuous coil spring mattress losing all of its original memory foam comfort layer it became too uncomfortable to sleep on my side so while I may start the night off on my side, I almost always wake up on my back.
Side comfort would be nice to have again, heh.

Hi amnj,

What you’re describing does seem to point toward the need for a bit more supportive material, perhaps even in the transition layer you’re using, based upon your feedback. But this is just an educated guess.

Phoenix

[quote=“Phoenix”]
You may wish to try a firmer Talalay on top, and perhaps the medium Dunlop beneath that to provide a more supportive transition layer. And whatever configuration you test, give it at least two weeks before changing, as it will take some time for your body to adjust. You can be surprised as to what feels too firm in one week becomes more comfortable in the second week as your body adapts. All of this is part of the trial an error of creating your own DIY mattress. Hopefully some of this information helps you out and points you in a better direction.
[/quote]Just an update.
I got a 3" Talalay in N4 (ILD 30-35 range) and it’s been 3 nights of sleeping on a N4, 65, 80 config.

I wake up with lower back soreness every morning since I started sleeping on this setup. My question is, if it takes at least two weeks for one’s body to adjust to a new mattress, does that mean you’re supposed to tough it out even if it’s causing pain/soreness?

I remember having a local salesman try to explain to me that he thinks you can test out mattresses in the store and know immediately whether that mattress is helping you have good spine alignment, and if you’re out of alignment then you can eliminate that configuration. Of course I realize that was his way of trying to get a sale vs. me going home and ordering from an online retailer.

Even though testing this is giving me lower back discomfort, on the plus side my shoulders feel better in comparison with my old spring mattress.

Hi amnj,

That’s a question only you can answer. It is normal to have some discomfort when adjusting to a new product, and after only three days it’s not enough time to make an evaluation of a product. If you think you’re sinking in too deeply, which can be a common issue with low back pain, you may wish to address the middle layer of your combination. But I don’t know what layers you have available to you. And I don’t know that your back pain is the result of the mattress not helping you to maintain a decent alignment, or if a more “neutral” alignment is even what might work best for you, as I can’t tell online what your level of strength and flexibility would be and what your body natural finds to be a comfortable resting posture. Maybe a N3/N4/80 combination? Or N4/N3/80? You seem to complain of hip pain if a bit too soft, and then back pain if too firm, so perhaps a combination of Talalay on the top two layers might provide you with better comfort but more support in the transition.

Phoenix

So I’m at that point again. I’m frustrated and still haven’t found the right combination of layers. In the last six weeks I’ve tested out (all layers are 3" thick unless I note otherwise):

N4, 65, 80 = lower back pain
2" 80, 65, 80 = Better but still some lower back pain in the mornings, plus shoulder pain
2" N2, 2" 80, 2" 70, 80 = scrapped the Dunlop65 and tried to go up to Dunlop70 but this still gave me lower back pain and seemed too soft
2" N2, 2" 80, 80 = started thinking maybe I need more firm so trying no center soft layer, still giving me lower back pain!

I’m starting to think my first evaluation back in the winter was completely all wrong. I suppose I’m headed the right direction since at least I don’t have hip flexor pain at all this round of testing. But that lower back pain just keeps appearing. It’s soreness that I can stretch away, so I’m fairly certain it’s from the mattress.

My original idea that lower back pain = too firm seems to be wrong too I think. I tried to read up on lower back pain and like you mentioned it tends to happen if the mattress is too soft.

I’m going to take your suggestion of making the top two layers Talalay and see if that helps. On the firmness scale, do you think N3 is softer than 80kg/m3?

Also, do you have any other ideas for configs I should test? Do you think it would help to sleep on just the 5" of D80 that I have and see what happens? It seems so thin but I suppose I could put either my D65 layer or D70 layer on the bottom to raise the height up a bit.

Hi amnj,

With the N3 from Talalay Global, they rate this as an ILD range of 25-30. Conversions of density to ILD aren’t quite as accurate with Dunlop, but 80 kg/M3 is generally considered to be in the upper 20-lower 30 ILD range, and most people would consider the N3 Talalay to be a bit softer than this Dunlop, plus the Dunlop has a higher compression modulus (gets firmer faster with deeper compression).

OLD CONFIGURATIONS/COMMENTS
3" 75, 65, 80 = Slightly too hard, lower back pain no lumbar support + husband had neck/shoulder soreness; but this is very close
2" N3, 65, 80 = Hip flexor soreness similar to when sitting too long, too soft?
N4, 65, 80 = lower back pain
2" 80, 65, 80 = Better but still some lower back pain in the mornings, plus shoulder pain
2" N2, 2" 80, 2" 70, 80 = scrapped the Dunlop65 and tried to go up to Dunlop70 but this still gave me lower back pain and seemed too soft

2" 65, 65, 75 = Too mushy/quicksand feeling
2" 65, 75, 80 = Hip flexor soreness similar to when sitting too long, too soft?
2" N3, 75, 80 = Too mushy/quicksand feeling
2" N2, 2" 80, 80 = started thinking maybe I need more firm so trying no center soft layer, still giving me lower back pain!
2" N3, 75, 85 = Too hard, lower back pain no lumbar support

Going over your previous comments, they really are a bit “all over the map”, and when I see feedback like this it can generally point back to not giving configurations enough time, a poor assessment of the comfort issues, environmental issues (not related to mattress but your state of health, strength, flexibility and sensitivity), or affinity for the substance (latex) being used.

You have some previous inconsistencies where a small change in the deepest support layer takes the mattress from “mushy” to “too hard”, and that wouldn’t be a normal reaction to a small change so deep in the comfort layers, so I agree with you that some of your old perceptions may not be the most accurate assessment of the configurations your tested. There has been a small underlying theme, which I think you’re coming around to, that slightly firmer upper layers are helping out, but you still want some contouring for the hip, which was why I had suggested some Talalay layers on top (perhaps doubling up “medium” Talalay layers), but not the very soft Talalay. I don’t think going with the design of the softer middle layer has been very productive for you, nor has the use of very plush upper layers been positively received in general. Aside from that, I don’t have any specific suggestions besides what I listed above, as I’m unsure (as are you) of the reliability of your previous comments. But sleep ergonomic research will tend to have you lean toward alignment and support, with “just enough” comfort layering to get the job done.

Phoenix