Hey Jay,
I know a super soft 10 ILD latex is possible, but generally when you get down into that ultra-soft range, you start making some compromises in durability and lifespan. I know @Arizona_Premium has a 14 ILD Talalay, and you can certainly find latex that gets softer than that, but there is a reason you don’t see high-quality Talalay commonly offered at 10 ILD. With the same type and quality of latex, the ultra-low ILD material simply doesn’t have the same structural resilience and long-term durability as a higher ILD version of that same latex.
What you may want to investigate instead is a TitanFlex, Energex, Malouf ActiveDough, or Serene foam. The first 3 are polyfoam latex alternatives. You may not need a 10 ILD in some of these other foams to get the same effect as the very soft memory foam with a bit of pushback, you are trying to duplicate. There are some reasons why you might not want latex at that low an ILD level anyway.
Traditional memory foam, like the 2.5 lb soft gel memory foam you mentioned, can handle ultra-low firmness levels because it relies on a viscoelastic structure rather than the same kind of elastic resistance you get from latex. It can compress deeply and slowly under relatively little force, conforming around the shoulder and arm and essentially allowing those areas to sink into the material. Its response is also affected by temperature and the rate at which it is loaded, which is a big part of why very soft memory foam can give you that “melting away” pressure relief.
Latex alternatives are engineered very differently. They are designed around a high-resilience polymeric matrix that actively pushes back and recovers quickly. That’s why you get the springy, resilient feel from latex and latex-like foams. So you have one type of polyurethane foam that is engineered to behave more like latex, while other polyurethane foams are formulated to behave more like viscoelastic memory foam, with additives and chemistry that give them that slower, more pressure-relieving response.
Manufacturing a latex down into the 10 ILD range isn’t simply making latex behave like memory foam of the same ILD. ILDs within different materials can and often will respond differently. You are taking an inherently resilient material (the latex) and reducing its resistance to deformation down to an extreme level. When you do this, you generally give up some of the structural robustness that contributes to the material’s longevity. That’s why I would be cautious about putting a 2–3" layer of ultra-soft latex directly in the comfort zone and expecting it to have the same meaningful life expectancy as a better-quality latex layer in a more moderate ILD.
So I would focus on those options I suggested if what you’re really trying to accomplish is a plush, pressure-relieving surface. You may find that one of those materials gets you much closer to the old memory foam feel without having to take Talalay all the way down to 10 ILD where the comfort preference does not align with the durability you expect or the comfort of VE memory foam.
I would also take a look at the overall construction of the bed you are creating. I don’t necessarily disagree that a 19–22 ILD Talalay may be too firm for you specifically, particularly since you’re sleeping on your side and you’re getting arm numbness and shoulder pain. But the problem may not lie entirely where you think it does.
You need to investigate your foundation, mattress protector, and sheets. If any of these are creating a situation where the protector or fitted sheet is overly snug, it can effectively tighten up the mattress and comfort layers, preventing them from having the amount of give they otherwise would have. I’ve seen this make a meaningful difference in how a mattress feels.
Additionally, many folks will use either a body pillow or a pseudo-body pillow, such as a queen or king pillow (I found a full body pillow takes up too much room in the bed, so I use one of my pillows in its place) placed in a way that, when you’re on your side, prevents you from rolling too far over onto the shoulder. That can reduce awkward pressure and also put the upper and lower arm in a much better position. Plus, your head pillow, if currently not at an appropriate loft, will allow your lower shoulder to dig into the mattress, impinging and placing pressure on that arm, causing the issues you are experiencing.
So before going all the way to 10 ILD Talalay, I’d look at the entire system. You may ultimately determine that you really do need something exceptionally soft on top, but I’d first figure out whether you’re actually looking for ultra-soft latex, or whether you’re looking for the pressure-relief characteristics of a very soft viscoelastic foam. Those aren’t necessarily the same thing. Additionally, your pillow, foundation and support layer all have to be considered in this investigation. Sometimes what our initial thought about what a pressure relief solution might be, is not that at all. There are arguments that could be made that too soft a comfort layer, cover panel, or topper is actually contributing to the impingement. You really have to view the entire system as a whole, when trying to solve this type of problem.
Hope this helps,
Maverick