Latex Firmness Measurement

[phoenix]

Hi Keyser,

Welcome to the Mattress Forum!

First of all, I appreciate Phoenix for this forum and the knowledge he imparts on us everyday. Thanks Phoenix.

You’re welcome.

Retail price of these mattress in the store are little over my budget, so purchased a king bed with both the configurations. My initial impressions are , bed is not as soft/comfy as the one I tried in the store and Dunlap firm, dunlap medium and talalay soft side feels slightly softer than dunlap firm, talalay medium and talalay soft side.

I’m a little confused here :S . Do you mean that you tested a latex configurable mattress in a brick and mortar store, but then purchased latex components online to create your own DIY latex mattress?

To bring objectivity to my subjective impressions, I need to measure the firmness (ILD) of each layer on both sites. While it is impossible to accurately measure the ILD at home on a 3" slab, a DIY contraption can be made to measure the relative differences in firmness between the layers. Atleast in my case, since all the slabs are of same thickness, the measured relative differences in firmness should be valid.

I’m not sure what you’re attempting to accomplish here, as your own subjective testing of how the mattress feels will be the most reliable indicator of your preference of comfort. If you’re simply testing to see how much weight can compress into each piece of foam and know that a “firmer” piece will require more weight to compress than a “softer piece”, my guess is that you already know this as the different pieces of latex you ordered would have been identified as such and most likely given an ILD range.

My idea of a cheap DIY contraption is to use a circular base of about 8" diameter and stack weights on it.
This website, pfa.org/jifsg/jifsgs4.html , says about 28lbs/50" sq pressure is needed to deflect 25" in a 4" slab. Going by that estimate, I assume I would need weights in the increments of about 1/2 lbs from 18lbs to 35 lbs.

ADMIN NOTE:Removed 404 page link | Archived Footprint: pfa.org/jifsg/jifsgs4.html

Those are specifications for polyfoam IFD measurements, and they are not relatable to ILD numbers of latex, as latex tests (usually) a 6" piece versus 4" for poly foam. The ILD of different materials or even different types and blends of latex also aren’t always directly comparable to each other (see post #6 here). Measuring the same tyoe of foam (latex) but changing the thickness of the foam sample tested also changes the results and the numbers would not be relatable due to the differences in the rate that a foam “firms up” as it is compressed.

ILD can be measured in different ways (different piece thicknesses, different dimensions of the tested piece, different disc sizes, different percentages of compression…). And ILD isn’t the only factor that affects the softness or firmness of a material so again using the ILD or other specifications of a particular layer or combination of layers as a reliable indication of how any mattress will “feel” or how firm it will feel to you compared to another mattress with a different combination of layers can sometimes be more misleading than helpful, and wouldn’t replace your own personal testing.

While your experiment might be a fun process to go through, you won’t arrive at any meaningful information that would translate to any ILDs offered to you from a manufacturer of foam pieces you may be considering either online or from a brick and mortar retailer, as your testing methods will be quite different from what the industry uses, as explained in the earlier post I linked to.

Phoenix