If you have ever come across a memory foam mattress, or read any of the Nectar bed reviews, you will have noticed two terms that people seem to use again and again, being “density” and “firmness”. Density is often used to determine whether a mattress is of high quality – the denser, the better. However, more density usually also means more money, although you do get increased durability in return.
Density is measured in pcf (Pounds per Cubic Foot), although most people will simply say “pounds”. Mattresses are available of between 2.5pcf and 9pcf, although it is said that there are no added benefits from going above 5.6pcf. Either way, density will tell you how durable the foam is, meaning how well it can retain the support and comfort characteristics the material is known for.
Understanding Density and Firmness
When people talk about density in relation to memory foam, they often mistakenly believe that it is the same thing as the firmness of the mattress. However, the two do not have to be related. It is very easy to find a high density mattress that is really soft, or vice versa. Firmness of a memory foam is expressed in ILD (initial load deflection). These range from between 10 and 16, with the highest ratings being the firmest.
What Density Is Right?
In order to properly understand the question of density and firmness, you first have to understand foam itself. Essentially, thousands of minuscule cells make of foam. These cells have a polyurethane casing and are filled with air. The thicker the polyurethane casing, the higher the density. The lower the density, the more air is in the mattress. Should density be too high, then the casing would become too stiff and thick, making it impossible for the material to contour the body.
The denser the foam is, the more expensive it is to create and there is always the danger of making it too dense. Hence, manufacturers have to consider durability, cost, and performance in order to create the perfect mattress. It is now widely agreed that 5pcf is the best possible rating for a bed. This is slightly more expensive, but it provides greater support and comfort, for a longer period of time.
The Base Foam
The next thing to remember is that, when you purchase a memory foam mattress, it is not 100% memory foam. Instead, the base of the mattress is polyurethane, closed cell, and only the top layers are memory foam. The polyurethane cells provide support for the memory foam. Usually, this layer is between 1.8pbs and 2.5lbs, which is highly durable in that material. Polyurethane is also not as dense as memory foam, but it is a whole lot firmer. Its firmness rating is between 20ILD and 40ILD. The good news is that, when it comes to the firmness of the base foam, the choice is simply yours. This is where you get to decide what real comfort means for you personally.