Memory Foam

Memory foam is polyurethane with additional chemicals increasing its viscosity and density. It is often referred to as "visco-elastic" polyurethane foam, or low-resilience polyurethane foam (see LRPu). Higher-density memory foam softens in reaction to body heat, allowing it to mold to a warm body in a few minutes. A lower-density memory foam is pressure-sensitive and molds quickly to the shape of a body pressing against it, returning to its original shape once the pressure is removed. Faster speed of recovery of a foam to its original shape after a weight is removed is sometimes claimed as an advantage by memory-foam mattress producers, who may talk of "newer generation" foams with "faster recovery."