High-Density Foam for Chairs or Couches

Foam Density

• Due to foam production technology advances, foam is now being produced in various ratings of densities and firmness. The ratings are expressed as two-digit numbers ranging from 1.8 to 3.2. The higher the rating, the higher the quality of the foam and the more durable it is. The density of the foam depends on the amount of urethane used in the foam material.

Firmness

• Firmness is referred to as "Indentation Load Deflection" (ILD). Foam is rated on ILD to let the furniture manufacturer and upholsterer know how firm the foam is. The ILD rating is measured by the amount of pressure (in pounds) required to compress the foam to 25 percent of its thickness. Firmness preferences vary greatly depending on the customer’s needs and furniture piece. For a standard medium-firm cushion, the foam should be rated at least 33 (pounds) and no more than 41 and be 4 to 6 inches in thickness. For a dining room chair, the rating should be 41 and 1 to 2 inches in thickness.

Foam Replacement

• Chair and couch foams should be replaced at least once every 10 years. Old worn out foam will begin to round on the front edge and won’t provide the sitting support of newer foam. The front edge of the foam is the first place foam starts to show age due to its greater degree of use than the rest of the cushion. In some cases, this can be temporarily restored with a steamer to save money and extend the foam's life.

Back Cushions

• The back cushions require different density and ILD ratings than sitting cushions. A standard medium back cushion should have a density of 2.4 and an ILD rating of 18. In cases where a softer cushion is desired, use a density of 1.4 and an ILD rating of 12. For thicker back cushions ideal for dining chairs, use foam with a density of 2.6 and an ILD rating of 28.