The Origin of Memory Foam

In the early 1970’s NASA’s Ames Research Centre 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, Tempur-Pedic, a Swedish mattress company introduced this material in a mattress form 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 Canada, United States and Britain began to develop their own visco elastic memory foam material to offer mattress, upholstering and specialty product companies the ability to allow consumers a wide variety of products and prices to choose from.

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 I 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 and weight sensitive, having the ability to rebound fairly quickly, returning to its original shape.  Memory foam is graded by its visco-elastic nature and durability by breaking down the grading system as follows: -
• Weight (Density in pounds per square foot)
The weight of the foam is determined by the amount of chemicals used in the composition of the polyurethane foam.  The more chemicals, the higher the density and the more visco-elastic it will become.  This density will not determine the hardness of the material, this is done through utilizing the ILD rating structure.  Most memory foam mattresses use a 5lb density, but some use as low as 2 or 3lb densities. Back to top
• ILD Rating (Indentation Load Deflection)
The ILD rating is going to tell you how hard or soft a material is.  The 25% ILD rating is the number of pounds required to achieve a 25% compression of a 4” thick foam using a 50 square inch indentation.  An example of this would be: - 20lb ILD foam indicates that this foam took 20 lbs of pressure to indent it 25%.
• Resilience
This measures the foam’s springiness by determining the percent rebound of a steel ball dropped from a height of 36 inches. The term HR foam refers to a highly resilient foam that will give a very high ‘ball rebound’ reading. Back to top
• Tensile
This indicates the extent to which foam can be stretched, measured in pounds per square inch and how much elongation in terms of percent of stretch before rupture.  This value has very little relevance to memory foam mattresses because they are not usually stretched and will become compressed only when slept on.
N.B. It is important to remember that these ratings can vary from each foam batch that is poured and that no mattress company can predict an exact rating on their mattress each time they produce the final product.  As an example, a 10 ILD rated foam could vary from 8 - 12 ILD each time the foam is poured.

What is the smell that comes from Memory Foam?
While the memory foam that comes from the U.S. does not contain toxic ingredients such as formaldehyde or PBDE, it can have a new foam type of 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 odours, 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.
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.
Also, you may want to look at the warranty a company offers, because you can then worry less about spending a lot of money for a mattress that has a good warranty period.

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. T his trampoline effect takes away from the overall support of your spine and can lead to back, neck and other types of painful disorders.
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 one inch to a four inch topper, but remember, most standard bed sheets will not fit over a greater thickness than a ten inch mattress. A two inch topper should suffice providing its ILD rating is high enough and providing it can offer that extra measure of body contouring you are looking for. It is a complicated scenario to find the best mattress topper to suit your individual needs.

How do Spring mattresses differ from Foam mattresses?
While a spring mattress was the standard for many decades, foam mattresses are becoming more and more popular due to their unsurpassed comfort and ability to support the body. While spring mattresses can feel nice to sit or lay on, they will not offer anywhere close to the body contouring and vital spinal support offered by memory foam or latex foam mattresses. It will actually cause a trampoline effect and bend inwards when pressure is applied without conforming to the specific bumps and curves of the body. While foam can shrink over time, springs can bend and lose their shape over time. Therefore, an old foam mattress will likely feel better and offer better support than its spring counterpart.

What is the difference between Memory Foam and Latex Foam?
Latex foam has a higher elasticity or resiliency than memory foam. The result is that Latex will feel springier and memory foam will feel more solid. Memory foam will not push back up against your body upon pressure being applied to it. Many mattress companies are using both these two materials to blend the perfect mattress combination. Rare allergies to latex can be triggered, but usually, this is upon contact with the skin, but won’t be triggered when natural and synthetic latex mixes, like talalay, are used. Talalay latex is a more supple version of latex. It is more expensive and is composed of synthetic and natural latex. Because there are no chemicals used in the latex composition, it is the ILD only that determines the feel of the product.

What is the difference between Memory Foam and Air mattresses?
Being able to change the firmness of your mattress with a simple control has made Air mattresses progressively more popular. With many Air mattresses both sides of the bed can be changed to different firmnesses. Unfortunately, Air mattresses have many parts that can and often do break and for this reason the small print in the warranties offers less coverage. Also, you will not get the same contouring of the body as you do with memory foam mattresses, as Air beds will not make an impression of your body. In fact, it is more similar to a spring mattress in so much as it causes a trampoline effect and bends inwards when pressure is applied without conforming to the specific bumps and curves of the body. This is due to Air being displaced to the sides of the body, leaving the middle with less support. Memory foam and Latex mattresses are the only substances that can accomplish a contouring of the body without losing support.

Does Memory Foam really help those achy joints?
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 latex added to a memory foam mattress 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.