Who would imagine that a fabric made from a tree could be soft and flowing, cool and comfortable, and need a lot of ironing? Counter-intuitive, isn't it?
We are used to the idea of something soft yet strong coming out of a silk-worm's bum and something warm and fluffy coming off a sheep's back, but we have the prejudice that any fabric with a name ending in '-ose' is going to be synthetic, and therefore hot, sweaty and uncomfortable to wear. One exception is viscose, a material that has natural origins and many unique properties.
What Is this Fabric Made from?
Viscose drapes and swings beautifully and the material is softer than cotton and more springy than silk. It is comfortable to wear and is great for dyeing. Viscose is a lovely fabric for floaty summer skirts, figure-hugging dresses, and underwear you want someone to notice. None of these are properties that are associated with man-made fibres, or any material that comes from a tree, for that matter.
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.
How Viscose is Made
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.
There were several suggestions and false starts for making artificial fibres, and during the great chemical upsurge in the mid-19th Century, cellulose was developed into substances and products as diverse as Cellophane, Celluloid, Acetate, Gun Cotton, Nitro Glycerine, and Rayon. Note that this list does not necessary denote that viscose is more explosive than any other fabric.
Early rayons had few of the advantages of modern viscose. Although they were absorbent, moisture tended to weaken them, and clothes would discolour and weaken in the underarms. These fabrics did not have the softness and drape of the modern fibres either. For decades man-made fibres were perceived as being inferior to natural ones because people associated the unpleasant wearing qualities of nylon with the structural problems of early rayons.
Nylon and polyester do not absorb water, and because your sweat cannot evaporate they can be unpleasant to wear. This is why nylon feels clammy. Sheets made from 100% cotton, linen or even silk (should you be so lucky) are more comfortable than nylon sheets because your sweat is absorbed by the fabric, and then evaporates. It is this absorbency which makes viscose so comfortable to wear.
The only real disadvantage of viscose is that most viscose fabrics do need ironing once they have been washed. This is not true of all viscose, and new ones are being created where the filament itself is more crease-resistant.