Hi jwilock,
You can read more about the different types and blends of latex in post #6 here.
If the ILD’s they gave you are correct and the latex comes from Latex International (which is the biggest source of Talalay in North America) then they would be “natural” Talalay which is a blend of 30% natural rubber and 70% synthetic rubber. Many retailers or manufacturers confuse the two. The 100% natural Talalay from Latex International doesn’t come in specific ILD ratings only in softness ratings from N1 to N5. The blended Talalay comes in ILD ratings of 14, 19, 24, 28, 32, 36, and 40-44 ILD. You can see their ratings here. When you see Talalay latex that comes from Latex International and it’s listed as having these specific ILD’s then it’s their blended Talalay. Another “clue” that can often be used to differentiate them is that the blended Talalay is usually called “natural” (as in the case of the Sleep Science) while the 100% natural Talalay is usually called “all natural”. I know it’s confusing and misleading.
Some of the blended Talalay mattresses on the members list are more than $600 less than the Sleep Science blended talalay mattress and some of the 100% natural are also less than that as well even though they use more costly latex and probably more wool in the quilted cover. They also have more flexible options to customize, re-arrange or exchange layers.
The main benefit of an “all or nothing” Costco purchase where you only have one option and don’t have the ability to choose a mattress that is customized to you is that they have a good return policy (see post #4 here) even though they don’t usually have the best price, value, or quality and other manufacturers also offer free or low cost return options as well.
Phoenix