I see the common concept is to put the softest laers up top, and increase density as you go lower. Thinking outside the box for a minute:
I know that I do well on cheap air sleeping directly on the chamber at moderate pressure.
I tried a Comfortaire with I believe 3" of latex over the 3.5" chambers and did not particularly care for it The ILD of teh latex may well have been too firm, maybe the poly foam in the quilting too soft I dunno.
What I was wondering is if anyone has tried a thin layer maybe say 1/2" or so of a moderately firm layer up on top of the stack? Kind of like puting a crust on top of the first layer of latex.
What you are referring to is what I call a “dominating layer” and it is certainly a viable option and a valid design (which I have personally tested and like in some instances). What it would do is change both the surface feel of the mattress (it would feel slightly firmer or more “crisp” as you put it and slightly reduce how far you sink in to the upper layers of the mattress). It is a more “sophisticated design” and more difficult to predict how it may feel for any particular individual (different weights, body types, and sleeping styles will “feel” it differently depending on how far they sink into the top combination of layers) but it’s also a great way to do some “fine tuning” on a mattress to get a surface feel you like but still be able to sink in enough to get the pressure relief you need.
In other cases … say where people have a S/M/F arrangement of 3" layers as an example … it may be a little too soft on top and not quite supportive enough so putting the soft in the middle and then the medium on top may “fine tune” the feel and performance just enough for them with a medium top layer providing the feel and most of the pressure relief they need and the soft (which in this case would be 3" deeper which would “come through” the top layer less) adding just enough extra give to fine tune the mattress to their liking. The only thing I would avoid in this case would be a thicker layer of soft on the bottom for alignment and support reasons.
I personally prefer thinner dominating layers on top when they are used but this is just my own personal preference and it would depend on how all the layers interact together and how well they “match” the needs and preferences of the individual. All the layers in a mattress interact together and sometimes even seemingly small changes like this can change the feel and performance of a mattress quite significantly. There are many manufacturers who use firmer quilting layers (or frmer quilting patterns) for a similar reason.
With air … it is much more difficult to match to any other material because it reacts completely differently from anything else. It is either fully compressed or not compressed at all and has no progressive resistance in between (with the exception of any stretchiness in the bladder itself). If someone does choose to use an air bladder as a support system … I would tend to suggest using it at the highest pressure you can and then build layers on top that can be gradually progressive to accommodate different weights or sleeping positions. More of my thoughts about airbeds are in this article.
As you mentioned … without knowing the specifics of the layers that were in the Comfortaire … you would have no frame of reference or be able to tell why it didn’t “work” for you because latex comes in many different levels of firmness and softness and there were likely also other layers involved so it would not really be possible to explain the “why” behind the “what”.
Overall though … it can be a great idea for those who prefer the benefits.
One of the mattresses that I particularly liked and have mentioned on several occasions when I was testing mattress for myself was a thin layer of latex over a fairly thin layer (2" or so) of memory foam. It’s different from what you are suggesting of course but it follows the same idea of a “dominating” layer over a softer layer.
As far as zoning goes … it can certainly be helpful in more unusual circumstances. With latex it may not be as necessary because of the nature of latex itself and it’s higher compression modulus than other foams (particularly with Dunlop) but even here it can have some benefits and allow for the use of softer foam under wider/lighter shoulders than may otherwise be possible. There’s more about zoning and some of my thoughts about it in this article.
I also agree that it can be very difficult to find all the different layering possibilities and test them in person. It can become a full time job all by itself and even then may need some “translation” or intuition because you may be able to test top layers that you are interested in but having them over deeper layers that are different also changes things and this has to be taken into account as well.
One of the things that most interested me about mattresses was the combination of technical information and intuitive processes that were involved in mattress designs and how they can interact so differently with different people. As many who have been in the industry for decades will tell you … the changes and the learning curve never stops