Hi FriendlyBacterium,
Welcome to the Mattress Forum!
Thanks for taking the time to write a detailed description of your process with your Best Mattress Ever. Iām glad you were easily able to acquire an exchange to the softer version, and Iām looking forward to your future updates on this item once youāve had a chance to sleep on it for a while.
A few comments on some of your other information:
Many boxed-bed manufacturers are now simplifying the exchange process by asking that you donate the item to a charity, which not only helps out someone in need, but also keeps the mattress out of a landfill. Iām glad you were able to easily accomplish this.
While counterintuitive, when a mattress uses softer materials in the upper comfort layers (here with 2" of 13 ILD 4 lb TitanFlex polyfoam over 2" of 18 ILD 4 lb Titanflex, versus your old 2" of 18 ILD 4 lb Titanflex over 2" of 28 ILD 4 lb TitanFlex), you will often āfeel throughā the softer layers to the firmer polyfoam support core, so the mattress can feel a bit firmer than what you would expect. Even experts in mattress design who are knowledgeable about the most subtle differences in ILD are often surprised at how different combinations feel in a completed product.
And yes, youāre correct that ILD is measured differently in latex and polyfoam. ILD in latex is usually measured with a 6" thick layer of foam and itās basically the weight that it takes to compress a 50 sq in round metal foot into the foam by 25% (which would be 1.5"). This is different from polyfoam which is measured with a layer of foam that is only 4" thick so it would only be compressed by 1" (and the ILD number would be lower than latex). So first of all latex ILD is not directly comparable to polyfoam ILD. Some latex manufacturers also produce cores that are a different thickness which would also produce a different ILD rating compared to testing ILD on a 6" core. There are also different testing protocols for ILD so in some cases the ILD would be tested at 40% compression instead of 25% compression which would also produce a different result.
Youāre welcome, and Iām looking forward to your updates!
Phoenix