A transparent, impermeable or semipermeable film of cellulose
used primarily in packaging, first developed by J. E. Brandenburger (1911).
Wood pulp is soaked in sodium hydroxide, shredded, aged, and reacted with
carbon disulfide to form a solution of viscose sodium cellulose xanthate.
This is extruded through a slit into an acid bath, where the cellulose is
regenerated as a film. It is dried and given a waterproof coating. If the
viscose is extruded through a minute hole, rayon is produced.