Definition of Polyurethane FoamMeaning of the Term as it Pertains to MattressesWhat is Polyurethane Foam? A flexible material, polyurethane foam is produced from combining polyol, isocyanate, and water. Flexible and durable, polyurethane foam is used as cushioning in an array of products such as furniture, packaging, car seats, and mattresses. All mattress foams, except for natural latex foam, are polyurethane-based. Polyurethane foam is the most common type of foam used in the mattress industry. Featuring open cell structures, polyurethane foam is highly breathable and flexible. Manufacturers can make foam feel and react as desired by adjusting chemical mixes and production processes to control foam qualities such as density, thickness, and softness.