Of the 5 major things that you must know about memory foam, density is the second most important thing on your list. But even though it's the second thing, it ties directly into the first item—which is the country of origin of the foam itself.
Let me explain.
For years now, I've warned people that memory foam mattresses and memory foam toppers made in foreign countries can have all kinds of harmful ingredients in them.
In the U.S., there are strict guidelines against using toxic chemicals such as CFCs, formaldehyde and PBDEs for example.
In a foreign country, they just don't have those kinds of regulations so you might end up sleeping on something like a toxic waste dump.
This is precisely what has given memory foam the bad rap about sleeping hot, stinking to high heaven and other things that foreign-made products cause.
In an attempt to make mattresses and toppers at blow out prices, many companies are importing their foam from foreign countries then making the covers in the U.S. and claiming "American-made" on their advertising.
Now, Let's Talk About Foam Density
Memory foam density is measured by cutting a 12" cube out of a piece of memory foam (think of it like a giant dice). This chunk of memory foam is weighed and the resulting weight is called the density.
For instance, if the cube weighs 5 lbs., it's then a 5 lb. density foam. Not too hard to understand, right?
For optimum support, you should only consider 4 lb. or more when you buy a topper. And for best support, you should select 5 lbs. density or more for your mattress.
This isn't to suggest that you should rule out a 4 lb. foam mattress.
I think many 4 lb. foam mattresses are more comfortable than most spring mattresses so at least you're getting some benefit for a lesser investment.
The reasons for selecting these densities is that you'll get better support from the higher foam density and the foam will last much longer.
Consider the 4 lb. foams as 5 to 10 year foam and the 5 lb. ones as 15-25 year foams.
I've had people call me and say that they bought a cheap 2 lb. mattress topper and it broke down in 10 months. Not good.
Now, you may be wondering why I said that even though denseness is second on the list. Again, it ties directly into the first, factor which is the country of origin.
Creating False Densities in Foam
Because consumers are becoming wiser about memory foam, lately most of the foreign manufacturers have began adding a clay compound into their memory foam.
This increases the weight of the foam so it appears to be of the higher quality, denser foams.
Exactly the opposite is true.
When you add clay to the foam, you ruin the very qualities that make it so desirable and you also greatly lessen the life of the mattress or topper.
So, foam density is critical, but creating it by sleight of hand and adding a foreign material to the mixture is false science.