Hi Mike 77,
All the layers of a mattress actually compress simultaneously not sequentially and they will each compress to different percentages of their thickness depending on their position on the mattress, the firmness of each layer, the compression modulus of the material, the thickness of each layer, and the compression force that they are exposed to (which depends on the weight of the part of the body in contact with the mattress and the surface area that is bearing that weight which is constantly changing as you sink into the mattress more or change sleep positions).
While “going through” a layer is commonly used as a way to explain things because there is a different amount of force that “goes through” a layer and compresses the next layer of the mattress depending on the hysteresis of the material (how much energy it absorbs) and on how point elastic the material is (how much compression affects or is affected by the surrounding areas of the layer) … it would be just as accurate to say that you will “feel through” the top layer meaning that you will feel the properties of the next layer down to different degrees. Even the softest latex won’t “bottom out” (meaning it has no more ability to compress because the walls of the cell structure are fully compressed on top of each other) if it is on top of another foam layer and will have the ability to compress more yet even though very soft latex will compress to a much larger percentage of its thickness than a firmer layer. Every layer of a mattress affects and is affected by every other layer in the mattress to different degrees.
The compression of each layer (mainly controlled by thickness, firmness, compression modulus, hysteresis, and position along with a few other specs) are what creates the pressure relieving cradle of a mattress in the top layers which re-distributes weight and pressure on the bony prominences and pressure points of the body while the resistance to further compression of the deeper layers is what “stops” the heavier parts of the body from sinking down too far and putting the spine and joints out of their natural alignment. The balance between the opposing needs of pressure relief and spinal alignment is the main factor behind all mattress design and theory and why different mattresses match the body types and sleeping positions and preferences of different people … or don’t.
There is no formula that can predict with any certainty what type of layering you may do best with that can possibly be more accurate than your own personal experience and as I’ve mentioned previously I can only provide general guidance.
I provided you a link on different sleeping positions in my last reply. Read it here.
If you’re unable to find any combination that is comfortable using your current mattress, and believe that it is due to the spring unit and wish to create your own system using a different base mattress or coil unit, you should read option 3 in post #15 here and the posts it links to in order to assist with that process.
Phoenix