Foamed plastics have been traditionally produced using CFCs (chlorinated fluorocarbons) as foaming agents. The international ban on the production of CFCs due to its role in upper atmosphere ozone depletion has prompted the industry to seek alternatives and carbon dioxide has emerged as one of the most popular.

Carbon dioxide is dissolved in the pressurised molten plastic and on extrusion, or other means of forming, the pressure is released and the gas comes out of solution forming small bubbles that create the foam.