Hi everyone, I would like to please ask for advice on my do-it-yourself mattress topper project. I have probably provided more information here than is needed, but as a novice I do not know which information is the most important in this equation. I hope I’ve at least organized this well enough to allow anyone interested to easily skim through for the relevant data points.
I purchased a 3 inch dunlop latex layer of ILD 28 with a cotton cover from Latex Mattress Factory, but unfortunately this seems to have been the wrong choice for my comfort layer, as it is not at all comfortable for me. I went with Latex Mattress Factory because I was impressed with their professional participation and support in the Mattress Underground forum. Even though I appear to have selected the wrong latex layer for my application, I still would say that I had (and still do have) the best possible chance to get it right thanks to the examples and other advice shared on this forum.
I believe that I probably need to exchange my 3-inch ILD 28 layer for a 2 or 3 inch ILD 19 layer… but I’m not 100% sure of this. Below are the details of my experiments so far. I would welcome any input and feedback from the forum here.
I’m male, 45 yrs old, 5’11" tall, 180 pounds. My butt is flat and I don’t have much of a gut and I have virtually no hips. I don’t get much exercise, so what little muscle I do have in my abdomen and back needs all the help it can get from my mattress to support me in my sleep. I tend to rotate between sleeping on my stomach, side, and back, although it could be that my tendency to rotate sleep positions arises from discomfort. With a more comfortable mattress I suspect I might possibly settle into mostly back sleeping.
My spring mattress is labeled as “extra-firm” and seems to be causing me back pain and muscle soreness all over, and it has gotten to the point where I feel sore not just when I wake up, but all day long, so I decided to see if a latex topper could improve things. I have been alternating between this extra-firm spring mattress and a softer mattress in another city that I commute to periodically. I do not see any visible sagging in this extra-firm spring mattress, and indeed, this extra-firm spring mattress while maybe not exactly comfortable for me, is at least tolerable for me for the first month or two after I come back to it, so I don’t believe that it is worn out. However, after a month or two of sleeping on this extra-firm spring mattress, that’s when the aches and pains start to accumulate and start to last all day.
I sleep on a twin-XL bed, as I find that a regular twin bed is too short for me.
My hope is to build myself an economical differential construction mattress (a soft comfort layer resting on a firm support layer). I want to use a single layer of latex as a comfort layer, and for the support layer I hope to use either my firm spring mattress, or a cheap-looking but firm 6 inch slab of foam that I happen to have cannibalized from an over-priced nearly-new (it didn’t get much use) LEESA brand foam mattress. (This LEESA foam slab had a 2" thick layer of egg-shell latex-ish foam-ish material that I removed from it.)
I understand that 2 or 3 layers of quality latex would provide for a better performing mattress, as opposed to my attempt here to get by with only 1 layer of quality latex, but I’m trying to save money while still achieving adequate performance.
I’m a professional quality inspector with experience in metrology, so I have at least some competence in performing repeatable measurements of stuff. I used my newly purchased 3 inch thick ILD 28 latex layer to calibrate a non-destructive do-it-yourself ILD measuring process in which I measure how many pounds of force is required to deflect downward by 1 inch of distance an 8 inch diameter area of the mattress while it is sitting on a wood floor. I have provided here these do-it-yourself ILD measurements in case they might be of interest in this equation. I refer to these as DIY ILD measurements to clarify that they are my derived figures as opposed to figures published by a manufacturer.
My DIY ILD measurements show that my spring mattress is DIY-ILD 28, and my cannibalized cheap foam 6-inch slab is DIY-ILD 29. Of course, the spring mattress, cheap foam, and dunlop latex will have vastly different properties as far as point loading and sag factor and such, but anyway, for whatever it’s worth (not much perhaps) my spring mattress, my 6 inch slab of cheap rigid foam, and my newly purchased 3-inch dunlop latex all appear to have similar ILD values.
I don’t think it makes much difference, but I will mention that my 6 inch cannibalized foam slab has an additional 2 inches of memory foam glued to it which I am unable to remove, however I am using this 6-inch foam slab with the 2-inch memory foam side on the bottom, facing the floor, so I don’t think the memory foam is going to contribute any significant sag or other attributes to the support performance of this otherwise fairly rigid 6 inch thick slab of foam. If it matters, the memory foam layer is DIY-ILD 12.
I tried laying on my back, with a pillow, on various configurations, and I arrived at the following ordering of these configurations, as ordered from least comfortable (producing the most immediately perceptible back pain) to most comfortable (producing the least back pain):
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the 3-inch ILD 28 latex placed on the DIY-ILD 28 spring mattress is the most uncomfortable, giving me immediate back pain.
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the 3-inch ILD 28 latex placed on a wood floor is almost as uncomfortable as when it was on the spring mattress, but is uncomfortable in a little different way that’s hard to explain… it manages to combine back pain with uncomfortable hard spots where I am sinking all the way through the latex.
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the bare wood floor with no bedding material at all is a little more comfortable than either of the first two configurations, with no immediate back pain when I lay on the bare wood floor.
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the 6-inch cheap foam slab all by its self is a little more comfortable than the bare wood floor. However, in this configuration, I feel uncomfortable in a way that is difficult to describe.
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the 3-inch ILD 28 latex placed on top of the 6-inch DIY-ILD 29 foam slab is the most comfortable configuration. In this configuration I again feel uncomfortable in a way that is difficult to describe. (again, the 2 inch DIY-ILD 12 memory foam layer is against the wood floor, so is not thought to be contributing much if anything to this configuration’s performance.)
So the million dollar question is: Why are configurations 4 and 5 uncomfortable? It’s difficult for me to perceive if my hips are sinking in too far, or not far enough, or what’s going on, but as far as I can guess, the answer may be that my hips may be sinking too far into the material, thus causing discomfort by messing up the curve in my lumbar.
At the 3:50 minute mark of this random mattress review video, the narrator asserts:
https://youtu.be/XnFs8xSbBdw?t=230
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Meanwhile, this Mattress Underground guide page asserts:
https://mattressunderground.com/mattresses/style-preferences-and-statistics/your-statistics
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At 180 pounds, I would think of myself as being more towards “heavy” than “light”. I also have a relatively flat profile from the back, side, and front. Per these guidelines, this would all seem to indicate the need for a relatively firm comfort layer.
I can’t explain why, but my intuition tells me that contrary to these guidelines, I might do better if I go to a more soft comfort layer, for example I might need to switch from my current 3-inch ILD-28 layer to an ILD-19 layer.
Before I cannibalized my LEESA mattress, it consisted of 2" eggshell pseudo-latex (DIY-ILD 24) on top of 2" memory foam (DIY-ILD 12) on top of 6" cheap foam (DIY-ILD 29) and the net result of all this assembled together was a reading of DIY-ILD 15… and this DIY-ILD 15 LEESA is actually more comfortable to me (though still not completely satisfactory) than any of the other combinations I’ve described here so far… But yeah that’s a complicated mix of materials in the LEESA so I wouldn’t know for sure how to interpret that result.
I get the impression that my ILD-28 layer would probably not be firm enough to use as a support layer, in which case I would be stuck with having to return it.
My being more “heavy” than “light” seems to indicate the need for a more thick comfort layer, but my being relatively flat seems to contradict this by indicating for a more thin comfort layer. Since at 180 pounds I am only moderately heavy, it would seem that my having a flat profile might be the more significant factor, and I should therefore go for the more thin layer indicated by my being more flat.
If I get an ILD-19 of 3 inches, then it’s not possible to go down to 2 inches without getting a whole new layer, but, if I get an ILD-19 of 2 inches, then I could always add on another ILD-19 of 1 inch from somewhere if I want to try a slightly thicker comfort layer. (Indeed, I could always try mixing in the 2 inch of egg carton pseudo-latex I scavenged off the LEESA mattress.)
So, there’s the puzzle. 
I would certainly appreciate any input and advice on what general mattress theory says that I might want to try next!
Thank you!
[edited to correct the value given for the 2" eggshell pseudo-latex (should be DIY-ILD 24)]