Mattress Buying Guide

Memory Foam Mattress 101

Visco-elastic foam, also called memory foam, is a popular mattress component. It's been getting a lot of press for its supposed ability to relieve back and joint problems, reduce insomnia, and give you a much better night's sleep. But is visco-elastic foam really all it's cracked up to be? Let's take a look at this pricey mattress foam, how it's produced, and what it can do for you. Learning how your mattress is put together can do a lot to help you buy the right bedding for your situation.

Production and History
Visco-elastic foam is basically a polyurethane foam, similar to the more conventional foams used in most mattresses. However, this type of foam is made with chemical additives that make it denser and more viscous. This type of foam was first developed under contract from NASA in the mid-1960s. The original goal of the foam was to make safer cushions for aircraft. It was eventually commericalized in pads for X-ray tables and football helmet liners and released to the public in the early 1980s. At this point, few companies were willing to work with the foam, since production was unreliable. One such company produced the Tempur-Pedic Mattress in 1991, opening the market to memory foam bedding.

Initially, these mattresses were used in medical settings, such as situations where patients were bedridden for long periods of time. Memory foam mattresses were shown to greatly decrease the incidence of pressure sores and gangrene from long immobility. Initially too costly for widespread use, this type of foam has become much less expensive, and is now commonly used in pillows, mattresses, and mattress toppers. It's also used to provide padding for people with long term pain and in cushions for wheelchair users.

Foam Density
Visco foam can be up to 7lb density (ILD). Memory foam mattresses are normally very dense and heavy, allowing them to provide good support without compromising quality. The unique feel of memory foam is often touted as a compromise between the solidity of a firm mattress and the comfort of soft ones. Foam mattresses are often sold by density. A higher density mattress is more supportive, usually slightly firmer, and also more expensive. Standard memory foam comes in densities between one and five pounds per cubic foot. The foam used in most visco-elastic foam bed toppers and in the comfort layers on innerspring hybrid mattresses is between three and four and a half pounds per cubic foot.

Foam Structure
Cell structures in memory foam vary significantly. Some foams have very open cells, while others have cells that are almost closed. Tighter cell structures provide less airflow, and can make the bed feel very hot. Some brands of visco-elastic foam are more open in structure, and are sold as "breathable" memory foam. Breathable foams have better airflow better recovery, and retain fewer odors. Since chemical odors are a major downside of memory foam mattresses, especially when new, this type of foam may be appropriate for people who are sensitive to these odors.

Health Factors
Some types of memory foam give off a strong chemical odor when they are new. This smell decreases over time, but some people do remain sensitive to it. These emissions can cause respiratory problems. However, visco-elastic foam mattresses have also been credited with reducing the severity and frequency of asthma attacks. This type of foam is less likely to harbor dust mites or mildew than conventional mattress materials.

Like other products made from polyurethane, memory foam offers a slight fire danger. All bedding in the United States must be resistant to ignition from open flames, but some worry that the fire retardants used on this foam can cause health problems. These fire retardants are no longer used in similar products in the EU. Memory foam mattresses may also present a danger to infants and very young children, who may have trouble turning over on the foam. However, older children and adults are not at risk, and many find that the foam helps alleviate other health problems.