Rayon and viscose are manufactured using the same method but differ in the materials used. Rayon is made from the cellulose of a variety of plants whereas viscose is solely made from wood cellulose.
In the process of making viscose, wood cellulose must first be isolated from the wood. This is done by cutting the trees into small pieces, treating it with calcium bisulphate and steaming it under pressure.
The ‘glue’ that holds the wood together (lignon) is then washed away, thereby purifying the wood cellulose. Wood cellulose is bleached and converted into wood pulp which is cut to the appropriate size and kept moist at 30°C.
Sheets of wood pulp are left to soak is a solution of caustic soda. The wet sheets are shredded into crumbs which are left for 48 hours to age.
The crumbs of wood pulp are treated with carbon disulphide and mixed slowly. This eventually creates sodium cellulose xanthate, which is dissolved into the thick, clear brown liquid that is known as viscose.
The viscose solution is ripened over 5 days before being pushed through the fine holes of a spinneret to form the regenerated cellulose fibres.
The fibres are wound onto a spindle, spun into yarns and then woven into viscose fabric.