Visco-elastic Memory Foam

A large percentage of todays mattresses incorporate a layer of viscoelastic memory foam as a comfort layer, below is some history and general information regarding this product.


In the early 1970’s NASA’s Ames Research Center funded a development project designed to create a substance that could help protect Astronauts from the incredible g-forces experienced during space mission take offs and re-entry. They believed that one of the key secrets to reducing g-forces on the body was to use a foam material that could conform to the shape of each astronaut and, more importantly, hold this conformity. While a foam mould of the Astronaut’s body shape could accomplish this, any movement would take the Astronaut out of this position and create incorrect pressure points against the body. Instead, they created a new foam material that was visco-elastic and therefore able to conform to the shape of the Astronaut, but return to its normal shape once pressure was removed from the foam. This could allow an even distribution of pressure or body weight over the entire surface of the memory foam, but, at the same time, quickly adapt to any movements of the body.

With this amazing discovery, Fagerdala World Foams of Sweden, Europe’s leading foam producing company, began experiments in the 1980’s to perfect this substance for consumer use. They trade marked the word Tempur to note the fact that this material was sensitive to temperature.

In 1991, the Tempur-Pedic, a Swedish mattress company introduced this material into mattresses and pillows to the Swedish market place and received excellent results. In 1992 the same products were launched in North America and similarly, received excellent results.

With the success of Tempur-Pedic, other foam manufacturers in around the world began to develop their own visco elastic memory foam material to offer in mattress and pillows.

Benefits of Viscoelastic Foam Mattresses and Pillows

A person who sleeps on their side places pressure on their shoulders and hips, a stomach sleeper places pressure on their neck and a back sleeper places pressure on their lower back and sacrum. Visco Elastic pressure sensitive memory foam offers the best chance for reducing overall pressure placed on all joints in these vital areas, by contouring them without pushing back against them. With high resilience foam added to a memory foam mattress base it offers a bit more spring against the concavities like the small of the back or sides, while not losing the ability to contour and displace pressure points.

Visco-elastic memory foam is widely used in medical bedding pillows and seating applications because of its unique attributes which can help aid comfort and sleep. Listed below are common points often put forward about visco-elastic foam and its properties

The heat sensitive visco-elastic memory foam moulds to the body improving posture and circulation.
The weight of the body is absorbed by the memory foam preventing bed sores.
The relaxed body has less desire to move and a more restful sleep is achieved.
Reduced movement means less stress on joints easing arthritic pain.
Correct spine alignment has enormous benefits to back pain sufferers

The structure of memory foam allows air to flow freely which helps to maintain a constant mattress temperature. The qualities of Visco Elastic ensure the most comfortable sleep possible because the foam is breathable, non-irritating and assists in the dissipation of moisture.

Head – Proper support will encourage the neck muscles to relax and help prevent tension headaches

Back – Aligning the back correctly on a memory foam mattress will lower the chance of back pain

Pelvis and Hips – A memory foam mattress will mould to the contours of the body. This reduces pressure thus reducing the risk of swollen hip joints or an aching pelvic area.

Lower Leg and Heels – Circulatory problems which can cause swollen calves and feet can be prevented by spreading pressure. Chaffing and soreness can also be avoided.

Some other commonly asked questions and answers on memory foam :-

How does Foam have a memory ?

To give a piece of foam memory, you start with a synthetic polyurethane foam material and add certain types of chemicals, which increase the weight or density of the foam. With the addition of these chemicals, a non toxic, visco-elastic foam material is created. However, there are many features along the way that determine what type of memory foam you end up with. To understand exactly what differences are found in each final product, first you have to understand how foam is graded.

How is Foam Graded?

For a material to be Visco-elastic, it will have to be temperature sensitive, having the ability to rebound fairly quickly, returning to its original shape. Memory foam is graded by its visco-elastic nature and durability , other factors on all foam grades are Density (weight measured in kilos per meter cubed) Hardness (measures in newtons) tensile strength and resilience and the classification of the foam.

What is the smell that comes from Foam?

New polyurethane foam can have a smell that can sometimes linger for up to a couple of weeks, depending on the foam manufacturer. Though this smell does not seem to trigger allergies, it can be a bother to people who are particularly sensitive to smells. If you are one of those who experience this, there are a few things you can try to help the smell dissipate quicker. Air out the room and wash the sheets after the first couple of nights sleeping on the mattress. Sometimes a dish of vinegar on the bed side table can help nullify the odors, or an Ozonator machine will rectify the situation very quickly.

How do I know my Memory Foam mattress is good quality?

Obviously it is important to allow the foam to do what it is best for: Allowing for a better contouring of your body shape and therefore less pressure placed on the areas of your body that press harder against the bed. However, don’t just go by your weight, because if you are tall then your weight is dispersed over the bed more. Look for the foam classifications as detailed ay the bottom of the page. A viscoelastic foam grade should be 55 to 60 kilo these are both very high foam density foams, but more importantly the base should be 39 kilo foam or above and ideally have a “V” classification, as there isn’t much point putting an expensive visco-elastic foam on a cheap mattress foam bottom layer. if all the foams used in the mattress are as above i.e. a 55 to 60 kilo viscoelastic topper and a “V” classification 39 or above kilo base foam, then the thickness of the foam is the other factor to consider make sure the visco-elastic top layer is 50mm or above and the mattresses total depth is 150mm or above and you should have a very good quality visco-elastic mattress.

A good memory foam mattress will not need a box spring underneath it to make the mattress feel good. You can use a platform base to increase the height of the bed, but remember this mattress should feel good even if it is placed on a level concrete surface.

Memory foam mattress or foam mattress topper?

Deciding on whether to invest in a new mattress or mattress topper can be answered by asking what your current bed has to offer. If your present bed is not so old and hasn’t lost its integrity or solidity, then a mattress topper may be just the savings you are looking for.

An old spring mattress can become lumpy or bumpy after many years, thereby making any mattress topper you place over it also lumpy and bumpy. You also have to worry about the possibility of sagging, which can cause a dip in the middle of the mattress resulting in a trampoline effect. This trampoline effect takes away from the overall support of your spine and can lead to back, neck and other types of painful disorders.

Most memory foam mattresses use a combination of HR (high resilience) foam and memory foam, the core of the mattress being high resilience and the top surface of the mattress having a layer of visco-elastic. The HR base foam will give the springy or bouncy attributes to the mattress and the top layer giving the unique comfort and support properties of visco-elastic foam. the thickness of the mattress varies from manufacturer to manufacturer and is often used as a selling point, some companies sell 200mm ( 8 inch ) to 250mm (10 inch) thick mattresses, this is mainly because domestic spring mattresses are this depth. the cost of these will be far more than a thinner mattress. However if a good quality base foam is used ideally a 38 kilos or above with a “V” foam classification then a mattress needs only to be 150mm thick. Many medical visco-elastic mattresses that are used 7 days a week 24 hours a day are 150mm thick. The thickness of the visco-elastic layer of the mattress should ideally be 50mm thick. Some mattresses with only a 25mm top layer don’t give the same feel that a deeper visco-elastic topper has. Also increasing the visco-elastic layer to 75 or 100mm gives little or no difference to the feel of the mattress from a 50mm top layer to many people. This is just a guide, different manufacturer’s foams will have different properties, and all mattresses react different to differing body weights. Overall the comfort and feel of a mattress will be subjective to the person using it.

If you determine that a mattress topper is suitable for your situation, the next thing you have to do is decide on the same principles that apply to buying a memory foam mattress; softness, density and thickness.

Depending on your existing mattress, you may want anywhere from a 25mm (one inch) to a 100mm (four inch) topper, but remember, most standard bed sheets will not fit over a greater thickness than a ten inch mattress. A 50mm (two inch) topper should suffice as in most cases you cannot tell the difference from a 50mm topper to a 75mm topper in use if on a good flat mattress.