Foam for Upholstery

    You use a much softer foam on the backrest than on a seat because, when you sit on foam you are putting much more weight on the seat foam. By contrast, when you lean against the backrest, you put very little weight against it. (Remember, most of you weight is going to the seat foam.)
     Most seat foam has a firmness rating of aprox. 26 lbs to 30 lbs (soft), 30 lbs to 40 lbs (medium), 40 lbs to 48 lbs (Firm) and 49 lbs to 55 lbs (Extra Firm)