The textiles in the form of fibres cannot always be used for consumer products except in products like surgical cotton, stuffing for pillows, quilts, mattresses and cushions. To convert fibres into fabric form as we see around us, they have to be converted into a continuous strand. Although there are some fabrics like felts or non-wovens which are made directly from fibres, in most cases the fibres are processed to an intermediate stage called yarn.

Yarn Processing
Yarn processing from natural staple fibres is called spinning, although spinning is the last stage in the processing. Earlier young unmarried girls were commonly involved in spinning the finest yarn because of their nimble fingers. The term ‘spinster’ for unmarried women originated in that context. Yarn processing, i.e., conversion of fibre into a yarn involves a number of stages. Let us take them one by one.

Let us take them one by one.

(i) Cleaning: Natural fibres generally contain extraneous impurities depending upon their source, like seeds or leafy matter in cotton, twigs and suint in wool. These are removed, fibres sorted out and converted into laps (rolled sheets of loose fibres).

(ii) Making into a sliver: Laps are unrolled and subjected to straightening processes which are carding and combing. The process is similar to combing and brushing your hair. Carding disentangles the fibres and lays them straight and parallel to one another. For finer fabrics the laps are subjected to combing after carding. This process removes finer impurities and short fibres as well. The lap then passes through a funnel shaped device which helps to convert it into a sliver. Sliver is a rope like mass of loose fibres, 2-4 cms in diameter.

(iii) Attenuating, drawing out and twisting: Now that the fibres have been converted into a continuous strand, it needs to be made to the size required. This is called attenuation. Several slivers are combined for uniformity. The slivers are gradually drawn out so that they become longer and finer. If a blended yarn is required (e.g., cotswol-cotton and wool) slivers from different fibres are combined at this stage. The resultant sliver is still of the same size as the original sliver. The sliver after drawing is taken to the roving machine where it is further attenuated till it becomes 1/8 of its original diameter. It is given a slight twist to keep the fibres together. The next stage is spinning. Here the strand is given the final shape as the yarn. It is stretched to the required fineness and the desired amount of twist given to it and wound on cones.

All manufactured fibres are first made as filaments. The yarn can be composed of a single filament or a multifilament yarn when a number of individual filaments are taken together and twisted as one. It is also possible to cut the filament into staple length fibres. These are then subjected to spinning process as for natural fibres and are called spun yarns. Staple length fibres are also required when a mixed fabric/blend like ‘terecot’ (terene and cotton) or ‘terewool’ (terene and wool) or ‘polycot’ (rayon and cotton) is required.

Yarn Terminology
(a) Yarn number: You may have seen certain numbers 20, 30, 40, etc., on the labels of thread reels. If you observe carefully and compare the fineness of the thread you will realise that thread reel with a higher number is finer. There is a fixed relationship between the weight of the fibre and the length of yarn drawn from it. This is designated as yarn number which becomes the indication of the fineness of the yarn.
(b) Yarn twist: As fibres are transformed into yarn, twist is added to hold the fibres together and is indicated as t.p.i. (twist per inch). Loosely twisted yarns are softer and more lustrous, whereas tightly twisted yarns may show as ridges such as in denim material of jeans.
(c) Yarn and thread: Yarn and thread are basically similar. Yarn is the term usually used in the manufacturing of a fabric, whereas, thread indicates a product used to join pieces of fabrics together.