Near the end of a short YouTube video (https://www.youtube.com/watch?v=KjqKaD-wolQ ) posted by Lucid Mattress as an infomercial about their 3 inch Ventilated Gel Memory Foam Mattress Topper, the company rep shows three blocks of their foam, in 2/3/and 4" thicknesses. She then leans onto each, and shows us how much more deeply her hand print sinks into the 4" than into the 2" thickness, and assures us that the 3" thickness gives results somewhere in between.
Assuming she applied equal weight to each slab, that result seems counter-intuitive. I would have thought that a given pressure, over a given area, would create an indentation of equal depth in each of the thicknesses.
However, the concept in the video is an idea that I’ve read before from several other online commentators and reviewers, who generalize that thicker slabs of memory foam will, other things being equal, create an experience in which the sleeper will sink further into the topper.
Does anyone have any ideas about whether the result shown in the video is actually true about the material itself, or more likely to only be true about certain types of memory foam, or certain products from Lucid?
Even if you don’t think the result shown in the video is generalizable across the product category of memory foam, can anyone suggest an explanation for how she produced her “magic trick”–other than not pressing equally hard on all three slabs?
In a similar experience I thought that adding an additional extra-firm layer of latex (a different type of foam made from rubber) to the support layers of my DIY mattress would make it firmer and more supportive. However what I found was the combination was actually more compliant and found myself sinking into the mattress more deeply with less support. When I consulted with Sleep EZ about my findings they explained why I experienced what I did, that with a greater height of compliant foam a given weight would sink in more deeply since there is more foam being compressed. This would happen even if the additional layer was extra-firm since it’s still compressing even though it does so less than a softer layer would. Once I thought further about it that made sense despite going against my initial expectation.
Hope that helps explain what you saw demonstrated in the video.
The problem that I have with Sleep EZ’s explanation involves my understanding (very possibly wrong) of how mattress toppers work. I thought that they were designed so that the force applied by body weight at any particular point along the contact surface was absorbed almost entirely by the compression of the foam, so that the area below the topper hardly registered whether force was being applied or not–unless the topper was too thin. I thought that was why thicker toppers are recommended for very firm surfaces, because otherwise the sleeper would “bottom out,” and his body weight would cause the topper to compress to the point that some part of the body would be almost in direct contact with the surface below the topper.
Relative to your example, you were essentially placing a second topper on the first. If you wanted to make your bed “firmer and more supported,” that would indicate that the comfort layers, which function like a topper, had lost much of their ability to absorb the force of your body weight, and you were essentially bottoming out. If you had removed the old support layer, and simply added the latex, I think you would have had a better chance of producing a firmer feel.
Just to be clear my entire DIY mattress is constructed of a stack of 3" toppers, a single Talalay 36ILD comfort layer on top of multiple Dunlop 44ILD support layers. The layers were all new so it wasn’t an issue of any losing their support and I wasn’t bottoming out. However going from two 44ILD support layers to three ended up allowing my body to sink and hammock slightly more rather than adding any additional support.
Thanks for getting back to me. You are a very adventurous mattress-maker. Even on this Forum, the preponderance of opinion is to discourage stacking toppers. Congratulations on achieving success for so long. I hope you can find the final tweak to make your stack again just like you want it.
Not sure what lead you to believe that stacking toppers is not commonly recommended, but many sellers of all latex mattresses provide exactly that. TMU Trusted members Arizona Premium Mattress, Sleep EZ, Latex Mattress Factory, Flexus, and others offer full latex mattress models which are available in custom configurations, and are constructed of 3 to 4 layers of latex toppers enclosed within a mattress encasement. Such builds offer great flexibility and durability since layer ordering can be optimized as your needs may change and individual layers can be replaced as required over time.
For the past 20 years, I have stacked two 2 inch toppers over a very firm inner spring mattress. Sometimes the two toppers are identical (so essentially 4 inch of same material), sometimes I have had a firmer lower level 2 inch with softer 2 inch on top. 4 inches seems to be perfect to me (over a very firm support base).
although, as mentioned in another post, one of my two layers is getting old and losing resilience. I tend to put the older one of the two (softer one) on the top, and newer one on the bottom. That way I can stagger replacing them, every few years.
I am trying to find a similar 2" high density > 5lb foam to replace the top one with, but having trouble finding a reliable one, and my past favorite brands (Sensus, Aerus, tempur pedic 2 inch) dont seem to be available any more so I’m a bit stuck at the moment with my old ones. It seems that the pandemic, raw material availability, high cost of petroleum/ petroleum products, supply chain issues, may all be a factor in some combination on availability.
I should add that part of the reason I like two stacked 2 " comfort layers stacked is because the support underneath (currently a firm mattress ) is very firm. If that mattress (or support layer if building DIY) was not as firm, then I might end up prefer 3 inch or comfort layer then…
You asked, “Not sure what lead you to believe that stacking toppers is not commonly recommended.” It was because that was the info contained in the snippets for the the top three items returned by Google using the search string [STACKING MATTRESS TOPPERS]. I didn’t know what TMU was at that time, and didn’t pursue a search here. Tonight, I did so, and found that multiple people have successfully done this. However, most of those discussions involve latex toppers. I’m glad you’ve had such good results for so long.