An Introduction to Progressive Construction

The common factor in all progressive constructions is that they use a comfort layer that is THINNER than the recessed areas or "gaps" in a sleeping profile. If for example you need a pressure-relieving cradle that is 3" deep (average side sleeper), then a progressive construction could have a comfort layer that was about 2" thick and the top 1" of the support layers would be used to form the rest of the cradle. If you needed a cradle that was 2" thick (common for back sleepers) then a progressive construction could have a comfort layer that was 1" or  1.5 " thick. In other words, no matter how deep a cradle you may need for your particular sleeping position or body profile, a progressive construction would use a comfort layer that is thinner than the depth you need and is designed to let you sink through it into the layer below. When you sink through it and into the support layer below, the qualities of the support layer "take over" and you can "borrow" its strengths to make up for some of the weaknesses of the thinner comfort layer above. For example you may wish to use memory foam in your comfort layer which is excellent at distributing body weight and relieving pressure but not so good with resiliency and holding up the lumbar. If you needed a 3" cradle and used 2" of memory foam, and put it over a highly resilient support layer such as latex or certain innersprings, then you would increase the resilience and lumbar support of the comfort layer while still being able to benefit from the pressure relief of memory foam. The deeper into a lower layer you sink, the more of its qualities you "borrow". This is why cheaper poor quality polyfoam can be used in the upper few inches of a mattress and by borrowing from the higher quality layers below, still feel good in the store and for the first little while .... until they wear out and lose their qualities. Sound familiar?

Natural fibers are a special circumstance. 

While they can provide good pressure relief in certain circumstances after they have "broken in" and formed a semi-permanent cradle in the comfort layers for effective pressure relief, they always need the help of high quality conforming support layers to help with pressure relief. These include Latex, HR polyfoam, and good quality Pocket coils or Offset coils. These mattresses also need special construction techniques to prevent compression of the fibers beyond the point that is needed for pressure relief and can be more expensive because of this. Budget versions of mattresses like this may not keep their qualities for long and with rare exceptions are usually not the best choice. They are also not as effective for different sleeping positions with a larger difference in profile (such as stomach/side sleepers) or unusual body shapes as the semi-permanent cradle that they depend on may not be appropriate for their range of sleeping positions or body shape.

Just to complicate this a little further, if a comfort layer is the same thickness as the gaps, then even though it would be a differential construction, the comfort layer itself may use a progressive approach such as 1" of latex over 2" of memory foam (or the other way around). In the same way the support core of a mattress can also use progressive techniques even in a differential overall construction. In other words, a progressive approach can be used within a comfort or support layer regardless of the construction of the overall mattress.

If this section has left you with the impression that choosing or adjusting a progressive layering can be a very complex process that has many moving parts, then you have an accurate understanding of the complexity of this method of construction. It is as much an art form as it is a science. While it can produce an amazingly comfortable mattress, it can often be much more difficult to get there than the more simple differential construction.

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