Viscose is a kind of rayon, which is made by dissolving cellulose (which is mainly wood pulp) and reforming it in filaments. Viscose takes its name from the intermediate viscous liquid, which has the colour and fluidity of honey.
The chemical and mechanical processes used to dissolve the cellulose and create the final filaments all contribute to the final properties of the thread. Cuprammonium rayon is dissolved in copper oxide and ammonia and ‘Cupro’ has become a recognised name for some forms of viscose. There are other chemical processes, and in fact, some modern processes for manufacturing viscose use water for the initial treatment of the raw cellulose.
The filaments are created using nozzles of different sizes and shapes, which can be stretched, doubled, twisted or spun. This can take place either in water or in warm air. With so many variables, manufacturers are developing fibres and fabrics with new weights and wearing properties all the time.
Most people assume that there are two kinds of fibres: natural ones, like cotton, wool and silk; and artificial ones synthesised out of petrochemicals like nylon and polyester. Viscose falls somewhere in between. The raw material for viscose is cellulose which is broken down either mechanically or chemically and reformed as fibres. Trees are 50% cellulose, cotton is 90% cellulose, so viscose is more accurately described as a natural, or recovered, fibre.