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Cellophane


Cellophane is a thin, transparent sheet made of regenerated cellulose. Its low permeability to air, oils, greases, bacteria, and water makes it useful for food packaging. "Cellophane" is in many countries a registered trade mark of Innovia Films Ltd based in Wigton, Cumbria, United Kingdom.

Cellulose from wood, cotton, hemp, or other sources is dissolved in alkali and carbon disulfide to make a solution called viscose, which is then extruded through a slit into a bath of dilute sulfuric acid and sodium sulfate to reconvert the viscose into cellulose. The film is then passed through several more baths, one to remove sulfur, one to bleach the film, and one to add softening materials such as glycerin to prevent the film from becoming brittle.

A similar process, using a hole (a spinneret) instead of a slit, is used to make a fibre called rayon. Chemically, cellophane, rayon and cellulose are polymers of glucose and contain the chemical elements carbon, hydrogen and oxygen.

Cellophane was invented by Swiss chemist Jacques E. Brandenberger while employed by Blanchisserie et Teinturerie de Thaon. In 1900, inspired by seeing a wine spill on a restaurant's tablecloth, he decided to create a cloth that could repel liquids rather than absorb them. His first step was to spray a waterproof coating onto fabric, and he opted to try viscose. The resultant coated fabric was far too stiff, but the clear film easily separated from the backing cloth, and he abandoned his original idea as the possibilities of the new material became apparent.


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