Hi gtwflorida,
Latex International makes both100% natural Talalay and blended Talalay but they have different firmness rating systems. Both of them are measured in 9 different places across the surface and then are given an official rating. The blended is rated with one of 8 actual ILD numbers that is closest to the average while the 100% natural is rated from N1 to N5 (you can see the LI ratings here). Because the “N” ratings don’t have a specific number … there are many manufacturers who will provide an approximate ILD so that their customers have a better idea of the ILD range even though the “official” rating doesn’t have one.
28 ILD is one of the “official” ratings for blended Talalay so you will most often see it referring to blended Talalay but you could also have a 100% natural Talalay layer that averages out to 28 ILD (which would be N3). You can see a picture here of an N2 layer which shows the 9 different measurements which average out to about 20.8 ILD. This could either be described as an N2, as 21 ILD, as “about” 22 ILD (which is the midpoint for N2), or as 20 to 24 ILD (which is the ILD range for N2). N3 layers will generally average out to between 25 ILD and 29 ILD so 28 ILD would be “in the range” of where a layer that was rated as N3 would fall.
All of this is to say that a layer that averages out to 28 ILD could be either 100% natural or blended Talalay but one would normally be officially “rated” or listed as 28 and the other one would be “officially” rated or listed as N3 but the retailer or manufacturer may call it 28 ILD for the convenience of the customer so they can make better firmness comparisons. In some cases the tag will still be attached to the layer (depending on which part of the original core the layer was cut from) but in many cases it’s not so you would need to check with the retailer or manufacturer to ask them whether you have an N3 and they just provided you with an approximate ILD or whether your layer is actually “rated” as 28 ILD (regardless of whether the actual average ILD was slightly different) and was blended. If the retailer understands the rating systems for each then they would readily acknowledge that you received an N2 but that they described it as 28 ILD as a convenience for their customer.
For reference … Radium has a rating system that is slightly different from Latex International that uses different numbers or ranges which you can seehere.
In the case of Arizona Premium they are well aware of the differences between them but if you are in any doubt about what you have they will confirm whether you have an N3 100% natural or a 28 ILD blended layer.
Phoenix