If you sank through Foam Factory’s 5 lb 12 ILD memory foam, moving to 14 or even 16 ILD is very unlikely to solve the problem, particularly with viscoelastic memory foam. On paper those numbers look different, but in real-world feel they’re still in the soft range. At 4" thick, low-to-mid teen ILD memory foam is designed to let you immerse into it for pressure relief. In addition, you will be enveloped by the foam and heat up like you are in hot lava quicksand. If your body is already compressing a 12 ILD 5 lb foam fully, you’ll almost certainly compress a 4 lb 14 ILD as well. The slightly higher ILD won’t overcome the fundamental issue: the foam is still soft and slow-responding.
Density (5 lb vs 4 lb) mainly affects durability and how “substantial” the foam feels over time, not whether you’ll bottom out. A 5 lb foam can actually feel softer initially because it contours more deeply and slowly. So switching to 4 lb with a small ILD bump isn’t a meaningful change in support. You’d basically be buying a variation of the same experience.
At this point, you probably need a material change, not just a small firmness tweak. A latex alternative foam like TitanFlex (Brooklyn Bedding’s high-resiliency polyfoam) will feel more buoyant and supportive. It compresses under pressure but pushes back more, so you don’t get that “stuck” sinking sensation. If your goal is pressure relief for side sleeping without feeling swallowed, this type of responsive foam can work much better.
Even more reliably, going with real latex in the 18–22 ILD range would give you contouring at the shoulders and hips while maintaining lift through your torso. Latex doesn’t allow the same deep immersion as memory foam, it distributes weight more evenly and keeps you more “on” the mattress rather than “in” it. For someone who has already sunk through multiple soft memory foam toppers, a 2–3" medium (around 20 ILD) latex topper is a much more logical next step than continuing to experiment within the 12–16 ILD memory foam range.
The readers digest version of it is, this isn’t a thickness problem, it’s a material and firmness category problem. Moving slightly firmer within very soft memory foam won’t change the outcome much. A supportive latex or latex-like foam in the 18–22 range is far more likely to give you the pressure relief you want without bottoming out.
I had been using a very firm talalay latex 3" topper. It was very nice for my preferences. Although the ILD of the topper was relatively close to my comfort layer ILD. The topper 36-38 and my comfort layer 36ILD, HD 1.8lb foam. The difference in material characteristics was very noticeable. The latex was actually not that forgiving at the higher ILD than the HD polyfoam.
I’m currently trying the Helix Premium Microcoil Topper in Luxury Firm, and it’s surprisingly close in firmness to my mattress and latex topper. The real difference is in how it responds, it contours much more naturally to my body thanks to the microcoils and layered high-density foams. I’m a bit bigger than you at 6’0”, 220 lbs, and it supports me well without feeling overly firm. Based on that, I’d guess the Luxury Plush could be a great fit for you. That said, there are probably several toppers that would work well, just not a soft, high-density memory foam option.
