Final weak-link check: all foam I can get densities for is 50kg/m³ (3.1 lb?), will 2" be a concern at that density?

Beyond Mattresses
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I can’t seem to find the density posts I 1st found this forum through and the tutorial only mentions high or low.

The mattress I’m tending towards now is softer for side-sleeping but I’ve finally confirmed the 5cm/2" - 50kg/m³/3.1lb/ft³ specs for the top memory layer, over 2cm of dunlop and 3cm of structured and flat polyfoam.

I know that density isn’t ideal, but the only places I’ve been able to get any density details all use it too, so I’m wondering if that depth will prove to be a weak link.

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My backup choice is firmer and uses (cover)2cm+2cm of bamboo & separate charcoal infused memory foam, over 2cm of polyfoam.

Would dual un-joined layers be more robust than a single layer?

They won’t tell me the densities, but the discontinued legacy version of their budget model was believed to 50kg/m³ memory, based on weighing their pillows; hopefully they upgraded the foam as well as the springs.

Thanks for any help.

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I’m sorry, I’m unable to answer this gibberish… :face_with_diagonal_mouth:… especially since memory foam and poly foam (whatever that is) are not my area of ​​expertise. :roll_eyes:

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Ok.
I wasn’t the tagger, but after 2 days I ended up going for the softer one.

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I simply abbreviated polyurethane to “polyfoam”, following the example of the the tutorial article and gave the densities in a metric / imperial format, thinking that might be easier to parse.
(I guess the fact that the units of measurement already used a ‘/’ was a bit confusing.)

I’ve seen some other sources list those same densities as either the minimum budget choice, or a premium option that should have high durability, so have no idea which to believe.

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The main question was: is 2 inches of 3lb medium-soft memory foam, as a 1st comfort layer, a weak link?

Hopefully it’ll be decent for the price, regardless of whether it’s the best.

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I must admit, I am not quite sure what you are asking either. Perhaps you would like to restate the question in a straightforward way.

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Is this foam you are referring to a viscoelastic memory foam at 3lb density?

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Indeed.

3.1 was just what I got from converting the metric value, so pretty much 3lb of viscoelastic memory foam.

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Here at the Mattress Underground, we generally say that anything less than 1" of lower-quality foam is acceptable, while anything more than 1" is not. However, this is a broad generalization, as other factors come into play, such as the formula of the foam, how it was processed, etc. Additionally, the placement within the mattress, and more. For example, VE memory foam is typically recommended to be 4 lbs or higher, though some 3 lb foams can be acceptable, although not ideal.

In general, the denser the foam, the more durable it said to be, assuming other factors, like the manufacturing process and foam quality, are also optimal. A 2" thickness is getting close to the limit and could be a weak link in terms of durability. It’s also important to distinguish between foam density and firmness, as they are not the same thing.

Brands like Tempurpedic (who has changed their formula a couple of times) and Backscience (which still uses 5 lb VE memory foam) create firmer mattresses, while Foam Factory’s 5 lb foam is much softer and has a much lower ILD (Indentation Load Deflection).

VE memory foam is typically used for pressure relief, contouring, and to add some plushness to your mattress. If that’s your goal, you’re on the right track. Alternatively, you could achieve similar results with a 2" layer of latex at your desired ILD. Some people prefer the “sinking” feel of VE memory foam, while others enjoy the more supportive pushback from latex.

In short, there isn’t a clear-cut answer as to whether this is a definitive weak point, but it does lean toward being a potential weakness. Ultimately, the best choice depends on what works best for you. If you have the opportunity, try latex instead of VE foam. If it works well, you’ll likely end up with a cooler, more durable mattress.

Maverick

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Thanks for this and the other help.

I’ve already made the purchase now, but hopefully it won’t be too problematic and I’ve at least got 6 months to trial it.

If I have cause to go to my other option would the fact that the top 2 layers of 0.8" VE are separate and un-joined be significant?

Though I guess that’s less than half an inch difference in total; the firmer bamboo & charcoal doped VE is probably a more impactful difference.

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When comparing two identical 0.8" layers stacked with one solid 1.6" layer of the same foam, the main difference lies in how the foam responds under pressure and how it wears over time. With two stacked layers, you’ll experience a more dynamic feel as the top layer compresses first, providing immediate softness, while the second layer offers deeper support once the top layer has compressed. This layered approach can create a more gradual transition from softness to firmer support. In contrast, a single 1.6" or 2" layer will compress uniformly, offering consistent support throughout. The compression will feel more even, without the distinct transition between layers, which might result in a smoother, more predictable response overall.

In terms of durability, the two stacked layers might wear a bit unevenly over time, especially if the top layer compresses more quickly. However, you could swap the layers to extend the lifespan and even out wear. The single 1.6" or 2" layer could provide more consistent durability because it’s uniform, but it could wear down at the same rate as the stacked layers if the foam material is identical.

If you look at heat retention, the stacked layers could allow for slightly better airflow between them, potentially reducing heat buildup. In contrast, a single 1.6" or 2" layer would likely retain more heat because there’s less opportunity for air to circulate within the foam. Of course, this depends on the specific properties of the foam used.

The stacked layers will generally offer more of a layered experience with a progressive compression feel, whereas a single 1.6" or 2" layer provides consistent, stable support. I suppose if you can discern the difference between the two, it will depend on whether you prefer a more adaptive, multi-layered feel or a uniform, even compression.

Most folks will feel like what the heck is the difference between if it is two 3" layers verses one 6" layer of the same material. But there is a difference in how they compress, move air around how the material retains heat.

How significant, I am not quite sure I know the answer to that.

Maverick

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Thanks for this @Maverick.

Those points all make sense, though I wouldn’t have necessarily jumped to them myself.

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