Softer surface causes more pressure points. How is it possible?

[skyisred]

I had an interesting experience at a store the other day. I’m very light-weight with bony shoulders, trying to find a mattress that will minimize shoulder/arm discomfort when lying on my side.
I tried a pretty comfortable mattress, it was 6in soft, 2 in extra soft dunlop, in a semi-stretch cotton/lycra cover. Its was good, but not perfect, so I asked to put an extra 2in extra soft topper on it (it was just a slab of latex with a sheet on it). Weirdly, I felt MORE pressure on my shoulder with this combination. It felt like I’m bottoming out, with my shoulder hitting a harder surface.
It doesn’t make sense to me. How can a surface feel less comfortable when a very soft topper is added to it?

[NikkiTMU]

Hi skyisred.

It does sound like you may be bottoming through the first layer extra soft dunlop. Maybe 3" of soft foam as oppose to 4" of super soft foam might be a good middle area? Or, perhaps 4" of super soft latex in a single slab?

NikkiTMU

[Mattrebuild]

@skyisred

I had an interesting experience at a store the other day. I’m very light-weight with bony shoulders, trying to find a mattress that will minimize shoulder/arm discomfort when lying on my side.
I tried a pretty comfortable mattress, it was 6in soft, 2 in extra soft dunlop, in a semi-stretch cotton/lycra cover. Its was good, but not perfect, so I asked to put an extra 2in extra soft topper on it (it was just a slab of latex with a sheet on it). Weirdly, I felt MORE pressure on my shoulder with this combination. It felt like I’m bottoming out, with my shoulder hitting a harder surface.
It doesn’t make sense to me. How can a surface feel less comfortable when a very soft topper is added to it?

I suspect the issue you’re running into is related to dunlop foam. In general with latex foam the further you push into it the harder it pushes back. Dunlop foam due to the way it’s manufactured firms up quicker than talalay so it does a great job with support but it’s not good when you need conformity (travel into the mattress). So when you doubled up the soft layer (all dunlop) you removed support for your torso (causing it to travel further into the mattress) and this caused your shoulder to also need to travel further but again dunlop firms up quickly so it likely increased the pressure on your shoulder (since that pushes into the mattress the furthest).

The way you fix this is to create proper support (alignment) and use just enough comfort layer to take the pressure off your torso/hips. Then create a simple zoning on the 2nd layer down (using soft latex) from your armpit to the top of your mattress. This will allow your shoulder to fully fall into the mattress and minimize pressure since your torso is being fully supported. I’d also suggest using talalay for at least the comfort layer and the zoned section since talalay is more conforming than dunlop.