Foam vs Memory Foam

Regular polyurethane foam is a staple material for bedding, used in both the comfort and support layers of mainstream mattresses for near about a century. However, the last few decades have seen an unprecedented growth in all avenues of technology – one of the seemingly trivial consequences of which has been the innovation and development of enhanced bedding materials.

Memory (or viscoelastic) foam is one such material, created with the intention to provide shock absorbing seats to astronauts being lifted into space, but ultimately finding its true calling as a therapeutic, conforming mattress comfort material.

Today, the market is flooded with products that utilize one or both of these materials at their cores, so it is important to know the characteristics of both, especially how they contrast and complement one another.

With that in mind, here’s a foam vs memory foam breakdown to provide you a basis for comparing mattresses that use these materials.

Basics of Polyurethane Foam

Polyurethane foam is perhaps the most widely used material in bedding (as well as a whole host of other applications). Low density polyurethane is favored by many manufacturers as a top layer material to create a soft initial feel (that doesn’t last very long) but does make for a good first impression.

Higher grade polyurethane (i.e. with higher density), is used to create highly resilient and progressively resistant support cores that hold up the more pressing parts of your body, that would otherwise sink through a soft comfort layer.

The durability of polyurethane is dependent upon its density: low density foams will start showing signs of deterioration a couple of years into their use, while high resilience foams will last for years without any tangible alteration in their performance.

The Pros and Cons

Pros

Generally inexpensive.
Available in a wide range of firmness ratings.
Can provide both resilient support and pressure relief simply by varying density and firmness.
Simple to maintain.
Cooler

Cons

Not as durable as memory foam.
Doesn’t provide conforming support.
Doesn’t completely eliminate motion transfer.

Comfort and Pressure Relief

Even low density polyurethane can offer decent springy support (though it won’t last very long, which is why I don’t recommend it at all, unless the mattress is to be used only sparingly). Moving on to HD and HR grade polyurethane – you can get resilient comfort that will last you for years, provided that the manufacturer does not go crazy with the thickness for short term good impressions.

Resilient comfort means that you’ll be getting a mattress that bounces back after you put pressure on it – the degree of firmness will determine how much it reacts to your body weight. For instance, the softer varieties of high density polyurethane foam could relax your pressure points through their compressibility alone – and at a much lower cost than the other candidate at that, but they’ll be less bouncy as a consequence.

Heat Retention and Breathability

While not the coolest material around, polyfoam does have an open cell structure which makes it automatically better at thermal conduction away from your body.

Durability

For both viscoelastic and polyurethane, durability is largely dependent on the density of the material.

Low density polyurethane foam starts to sag after a couple of years – sooner if it is used more ‘intensely’, but high quality, high density foam (with density north of 2 lb./cu.ft.) can be expected to last far longer. That said, it still won’t age as gracefully as viscoelastic does.

Motion Transfer

While polyurethane is not terrible at reducing motion – especially the firmer varieties – it is not as point elastic as viscoelastic foam, and does transfer some of the pressure to the farther reaches of the bed.

Basics of Memory Foam

Memory foam is a viscoelastic material: it is known for its ability to both absorb and redistribute pressure from a body falling upon it, enabling it to form a conforming cradle that matches your sleeping style – this in turn results in pressure being taken away from the hard points e.g. hips and shoulders for a side sleeper, so that a more natural spinal position can be achieved.

Viscoelastic foam by itself isn’t able to provide total support – pressure relief is more its forte. For a mattress to be both supportive and pressure relieving, the base will need to comprise of a harder, more resilient material such as HD polyfoam.

In terms of composition, viscoelastic foam is closely related to regular polyurethane, with the exception that it uses additional chemicals to achieve its viscoelastic nature. High quality viscoelastic foam – that is to say, with a density surpassing 4 lb./cu.ft., usually retains its conforming ability for much longer than other types of foam.