CELLOPHANE

regenerated cellulose extruded into thin, flat, transparent sheets. Extrusion through a small hole or spinneret produces a fibre, rayon. Highly impermeable to dry gases, grease, and bacteria, cellophane is used chiefly to package food and other perishables. It is frequently given a moisture-proof coating and is sometimes dyed. In the manufacturing process, an alkaline solution of cellulose fibres (usually wood or cotton) known as viscose is extruded through a narrow slit into an acid bath. The acid regenerates the cellulose, forming a film. Further treatment, such as washing and bleaching, yields cellophane. The name is trademarked in some countries.