Everything you need to know about Polyurethane Foam
Flexible polyurethane foam, also known as polyfoam, is a synthetic material derived from the reaction between two petrochemicals: polyols and isocyanates. Polyfoam is most often used to create the comfort layer in innerspring mattresses, but it may be used in foam mattresses as well. The material is also found in couch cushions, and used to make ‘egg-crate’ mattress toppers and sleeping pads.
Polyfoam is considered the lowest-quality material for comfort layers. This is primarily due to its relatively low density, which causes the material to break down and degrade much faster than other materials. As a result, body impressions will form in the mattress surface rather quickly. Due to its composition, density is the more practical way to measure polyfoam mattresses (as opposed to ILD/IFD). Three grades of polyfoam are available: high (HR), medium (HD) and low (conventional). These grades are differentiated by density, as well as compression modulus, a measurement used to determine the stress-to-strain ratio in an object when pressure is applied. The table below explores the differences between these three grades.
|Polyfoam Grade||Trade Name||Density (Pounds per Cubic Foot)||Compression Modulus|
|High-grade||HR Polyfoam||2.5 lbs/ft3 or higher||2.4 or higher|
|Medium-grade||HD polyfoam||1.8 to 2.5 lbs/ft3||2.1 to 2.3|
|Low-grade||Conventional polyfoam||1.8 lbs/ft3 or lower||1.8 to 2.0|
One thing to keep in mind: According to the International Association of Bedding and Furniture Law Officials (IABFLO), any mattress sold as HR polyfoam must have a density of at least 2.5 pounds and a compression modulus of at least 2.4.
Polyfoam is soft to a degree, but it will not conform to your body or target pressure points in the same manner as latex or memory foam. If you prefer a contoured fit or have chronic back or joint pain, then you should check the polyfoam content of any mattress you’d like to buy. A good rule of thumb: avoid mattresses with more than one inch of conventional polyfoam. One thing to remember: many mattresses labeled as ‘latex’ or ‘memory foam’ contain polyfoam layers, so it’s always best to inquire about these components before you buy.
Green certification is another issue with polyfoam. Most polyfoam mattresses will carry the CertiPUR-US® certification, which is awarded by a nonprofit organization named the Alliance for Flexible Polyurethane Foam, Inc. This certification ensures the foam doesn’t contain mercury, lead, heavy metals, formaldehyde and other hazardous materials, and that the manufacturing process produces low VOC emission levels. However, CertiPUR-US® has been criticized over its connection to the polyurethane industry, and the certification does not carry the same weight as third-party or independent eco-labels like Oeko-Tex 100 or Eco Institut; these certifications are usually only awarded to natural and, in some cases, synthetic latex.
On the other hand, a polyfoam mattress will be suitable for anyone who does not have any special sleep preferences. Polyfoam is found in most mattress models, so the price will vary by brand; expect to pay between $800 and $2,000 for a polyfoam mattress, depending on the brand and the density grade.
Before buying a mattress with a polyfoam comfort layer, here are some important considerations to make:
- What is the polyfoam grade? Conventional polyfoam may deteriorate in less than a year, while HD and HR polyfoam have longer lifespans. Remember to check the density and compression modulus of the foam to determine the grade, regardless of what the label says. Also ask about the thickness of low-grade polyfoam layers; you may want to steer clear of mattresses with conventional polyfoam layers that measure more than one inch thick.
- What is the polyfoam content? Since polyfoam is so inexpensive, mattress manufacturers will often use the material in mattress comfort layers. This is even true of mattress models sold as ‘latex’ or ‘memory foam’.