How to buy a Memory  Foam Mattress
Not all visco elastic or memory foam mattresses are equal. Mattress toppers are also made differently. This section will explain what you need to know .
Standard foams in mattresses are made from polyurethane. There are many combinations of chemical add to an oil base there for there are many polyurethane foams. The stiffness, length of time, durability comes from the added chemicals not the oil base. The polyurethane that is used for packaging are generally stiff and brittle. Some of this type of foam unfortunately is used in the base or sides of some mattresses. A mattress top also uses polly foam but is softer and more durable. There are many grades or types of these foams also so when you are told it's a density of 5 it sounds impressive but is only half the story.
Visco foam is exactly as described above with one major difference. Regular polyfoam is built with closed cell placed tightly together. Think of it as little balloons pressed tightly together so you just couldn't put any more in without the balloons breaking. There would be no airspace between them so when you pushed on them you would feel them pushing back. If you pushed hard enough and long enough these balloons would start to break. The same thing happens to the foam on your mattress. Visco foam is made with open cells which allows air to flow in and out so if you were to push on it would give and it would take a greater amount of pressure and longer to break these cells.
When you lie on a good visco mattress there is no air left in the cells where the most weight is yet enough to give support where the body isn't pushing down as much. In other words it supports where you need it while offering low pressure and comfort where you press the hardest
If your buying a visco,memory foam mattress or mattress topper you will see many brands and price ranges. The difference between them starts with original chemicals used to make the foam just like in regular poly foams. There is one area that is also critical and never mentioned when you are being sold the product. All of these mattresses are a layer or group of layers of visco over a hard polyurethane block.You need to know first not if it is an8 or 10 up to 18 inch mattress but how much is visco and how much is base foam. The amount of visco is the amount of pressure relieving the mattress can give, so 2 inches of visco is the same no matter how thick the mattress. The next question should be the density of the foam I would recommend a minimum of 5. Regular poly foam in mattresses ranges between 1.8 and 2.5. Visco mattress pads generally range between 2 and 4 density the higher the density the more the pad is able to provide comfort but as with a visco mattress it is the original chemical composition that will make it more or less durable.
Lets get rid of the baloney
TempurPedic is the best brand. No they are among the better manufacturers but if you remember the advertising rules good is anything, best is equal to and better has to be better. Even worse you can say better if there are worse ones. This company may be the better marketer in the mattress business then again they may be second to Sleep Comfort (air bed manufacturer)
.Used by NASA ;sorry they developed it not for bedding but to lessen "G" forces while taking off and reentry. They didn't use it.
The Swedish Tempurpedic company not to be confused with the American manufacturer did develop one of the original foams for mattresses but Sweden isn't the only or largest manufacturer of the foam.
My Favorite by convoluting the foam it keeps the mattress cooler. It can't there is no air pocket once the foam is compressed. What it does do is let a manufacturer claim more product. Foam is measured from highest point of one side to highest point of the other therefore there is less material in 1" of convoluted foam than a flat piece at the same 1"

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