Most upholstery foams are made of polyurethane (a combination of polyol and diisocyanate) and the term “polyurethane foam” is a generically used term which covers everything from memory foam to high density foam. Overall, foam is the firmest of all upholstery fillings although it does come in varying materials and densities.
In many countries, including the UK, these densities are distinguished by their corresponding colours—pink, white and blue. In the States, upholstery foams are given an Indentation Force Deflection (IFD) rating which denotes their firmness.
Lower IFDs are softer; higher IFDs are firmer. In high-end upholstery, multiple foams are used in a single sofa so that individual areas are given completely tailored support. UK foam manufacturers are obligated to comply with the national standards and all foams should be of a high quality.
Sofa foams made overseas don’t always have such strict regulations and, therefore, are usually of inferior quality. Inferior foams are not comfortable, do not provide adequate support and will deteriorate very quickly. Foams from overseas must be CMHR combustion modified and high resilient to comply with UK legislation.