If your foam cushion material is older than about 10 years, or if it is beginning to have a "rounded" front edge, or if the seat foam doesn't offer you the support you need to feel comforatable, then you are probably ready for new foam. Foam production technology has made some very significant advances in the past decade. Foams of varying densities (Quality)and ILD (firmness) ratings are now produced which offer the furniture manufacturer or Upholsterer an opportunity to select a specific type of foam based upon its intended use. Foam is rated according to various performance tests.
WHAT MAKES A GOOD FOAM?
There are three performance tests that are of primary concern in evaluating the suitability of foam. The first concern is if the foam is rated as HIGH RESILIENT (HR). The next concern is the DENSITY rating of the foam. And finally, the INDENTATION LOAD DEFLECTION (ILD) rating is also an important factor in selecting a foam material for your new cushions.
HIGH RESILIENT (HR) foam is what you might think it is. It is a foam material that is produced to offer a longer useful life than non-HR foam. HR foam is often also rated as fire resistant (FR). Tell your Upholsterer that you are concerned about fire safety and long life of your new foam and ask him to verify that your new foam is rated both HR and FR.
The DENSITY rating of "High Density" furniture foam is expressed as a two digit number which may range from 18-32. Actually, there is a decimal between the two numbers which makes the density rating of the #18 foam a 1.8 foam. The density rating of the foam material is the best indicator of the quality of the foam. The higher the density rating... the higher the quality of the foam and the longer you can expect it to maintain its shape, loft and support. In the production of foam, there are two basic ingredients which are the urethane chemical that is the foam, and air. The more chemical that exists in the foam material, the higher its density rating will be. In the above example, the 1.8 rating means that there is 1.8 pounds of chemical in each cubic foot of foam material. A cubic foot is equal to an area that is 12" x 12" x 12".
The next rating of concern is the INDENTATION LOAD DEFLECTION (ILD) rating. This is a measure of how much pressure it takes to compress the foam 25% of its thickness. For instance, if your seat cushion is 4" thick and has an ILD rating of 33, it would take 33 pounds of pressure to condense the foam to a thickness of 3". The ILD rating of a foam material will tell you how FIRM the foam is.