Foam is a common material that is often used in furniture.  Because there are
many different grades and rating standards of foam, one may ask, "What makes
a good foam?"  A popular choice for home furnishings is High Resilient foam.  This
material is fire resistant and offers a long, useful life.  The density rating of foam
is a 2-digit number that represents the amount of chemicals in the foam. Therefore,
the lower the density rating is, the less supportive the foam will be because there
are not as many chemicals in that particular material.  So if you are planning a
trip to go foam shopping, don't forget to ask about the resiliency and the density
rating.

For more information about foam and its standards and ratings, check out:

     http://home.att.net/~upholsterybycaroline/furniturefoamcushionmaterial.html