The Sleeptek saga continues…
In trying various combinations, one of the more comfortable we’ve found is a 4" New Firm (which is softer than an Old Medium) + 4" Old Firm or Old Medium + 2" soft topper. This is all on top of a Sleeptek foundation.
Will having a softer bit of latex under the firmer latex cause the firmer latex to break down or wear out sooner? Or any other reasons not to do this?
Thanks,
Hi JohnQ,
Good question. What you’re describing is having a “dominating layer” on top, and many people prefer this feel, as it offers a bit more of a “crisp” surface comfort that’s a little less point elastic. As the uppermost layers of the mattress receive the most specific compression and use, having a more durable layer above the softer layer would extend the life of the soft layer beneath the firm dominant upper layer.
There’s a bit more detail about dominant layers in post #33 here.
Phoenix
Hi, So glad I found your posts on Dominant Layering. I recently bought a medium latex mattress with a 7", 65 ild core and a very lightly padded soft tencel cover; bringing the overall thickness to 9". It’s glorious for me but a bit too soft for my partner. In your estimation might a 3", 85 ild topper work to give a less “sinking in” feeling? Is that combination of thicknesses and differential of ild a viable idea?
thanks so much
K
Hi key,
Welcome to the Mattress Forum! 
While I can’t predict how this combination might feel for you, there certainly would be a difference in comfort from your current mattress (65 kg/M3 is a bit on the softer side for a latex core) and you should notice a substantially firmer surface feel going with the 3" version of the 85 kg/M3 on the top of your current mattress, and there would be no reason to think that this wouldn’t work well to “firm up” your current setup.
If you do decide to make such a change, I’ll be interested in learning of your results.
Phoenix
Thanks for the warm welcome! Since writing my question, I’ve on another post of yours re dominant layering where you recommend avoiding a thicker soft base layer. How thick is too thick? Thank you.
Hi key,
There isn’t an exact answer to your question, and it depends upon the individual and the material being used. You may have read one of my comments regarding a three-layer (3" per layer) system where I was advising caution about using a very plush layer in both the middle and the lower layers of the mattress with a firmer “dominating” layer on top. In this configuration, there would have been a total of 6" of very plush latex (it was probably Talalay in that example) on the bottom of the mattress, not allowing for adequate “deep support” and possibly resulting in poor alignment characteristics.
The mattress you have currently uses a 7" of 65 kg/M3 (not ILD – I forgot to mention that in my last post) of Dunlop latex, which most people would consider plush. I forgot to ask yesterday of the exact layerings within your mattress, as latex is poured in 6" cores, so I was curious if you had different layers laminated together. Dunlop does have the advantage that it has a higher compression modulus (it “firms up faster” after about 25% of its initial compression) than Talalay latex, which is one of the reasons that many people prefer to use Dunlop in the lower support layers of a mattress. While this would be for most people a bit of a softer choice for a mattress, it seems to have worked well for you. And in your situation it seems that you don’t have the ability to customize, so the issue of “how thick” isn’t applicable. Adding 2" of the 85 kg/M3 should add “a little to fair” amount of extra firmness on the surface, and adding 3" should be a substantial difference. If your alignment was fine with your initial set up, the addition of this topper in a firmer version shouldn’t impact that negatively.
Phoenix