Do 2 layers behave different than 1 layer, all things being equal?

Hi folks, just a random completely academic question.

By example, some mattresses will say 1 layer of 3" latex, soft, and others will say 2 layers of 1.5" latex, both soft. All things being equal, do 2 layers perform differently than 1?

The things I’ve come to is that:

  • you might be able to replace the topmost 1.5" cheaper than a full 3" if doing maintenance.
  • 2 layers could have different characteristics even while both being described as soft (e.g. different zoning, different pinholes, different ventilation channels, etc).
  • maybe, 2x 1.5" feels softer than 1x 3", with identical latex?
  • maybe it has to do with efficiently using the source material? If, during manufacture, you produced 4.5" thick layer, but really wanted to sell 3" layers, you would end up cutting it into 2 pieces and would be motivated to sell 1.5" layers.

Just a random academic question. While I’ve used 3" and 2x 1.5" in this example, as that’s something I recently read, other thicknesses are sometimes referenced.

Hi dn,

Two individual layers that are the same type of material and the same ILD (all things being equal) and that aren’t glued together will generally “act” a little softer than a single layer of the same thickness because the two layers can flex and respond a little more independently of each other than a single layer. This is also assuming that the cover and all the other layers are identical as well because every layer and component in a mattress will have some effect on all the other layers. Some people that are more sensitive to more subtle differences would feel this more than others.