I am a simple person – simple in tastes, simple in looks, simple in manner, and simple of intellect too, as those in the know would say. Maybe because of this I am always looking for simple explanations for the complex things around me.
And the steps and processes involved in the transformation of fibers, like the one from a pod of cotton to yarn and then to hundreds of beautiful fabrics seems like one of those mind boggling complex things which needs a simple explanation – So here are the key processes in simple terms.
The fabric making process – a simple step by step overview
This is, of course, the first step. Fibers are the building block of a fabric and they are generated or produced by many means – man-made fibers /synthetic fibers and natural fibers are all made following many practices including sericulture for silk, cattle rearing for wool, various chemical processes etc.
Plant fibers like Cotton and jute are cultivated. Synthetic fibers like polyester and nylon are made by pouring molten polymer solution made by special chemical processes, through holes in a spinneret and the resultant filament is wound up to form those fibers. Fibers like Viscose, Bamboo, Modal and All Blends are all man made fibers produced following a set of specific processes.
In the case of cotton, the cotton seeds are removed from the pods first – this is called ginning. Opening is the term that indicates the extraction of fibers from the cotton bales
For synthetic fibers the next few steps are skipped – filaments are spun into yarns and wound.
The fibers are cleaned of dirt. In the case of wool, the raw loose fiber is first scoured, washed, dried and blended – this is a compulsory process that is necessarily done at this stage. In the case of other fibers, scouring may occur after the fabric is made as well.
Carding & Combing
Fiber at this point is an entangled mass of fibers – they are passed through a carding machine so that the fibers are cleaned from all impurities and a continuous web/sliver of fiber is produced – the fibers are arranged in a parallel manner. This is a very important process in the production of staple fibers. You can learn more about carding here.
In the case of woolen fibers carding and condensing are done. In the case of worsted fibers in addition to this combing is also done. Combing is a process in which the short fibers are removed.
A number of slivers of the fiber is then combined to form a wide fiber.
The fibers are blended into a roving at this point – Roving is a long and narrow bundle of fiber. It is wound onto a roving bobbin.
The roving is then spun (pulled, drawn and twisted) into yarn and this process is called spinning. A yarn is a continuous length of interlocked fibers. Combed or Carded Cotton; Polyester Cotton blends; Linen Cotton blends; Rayon (filament or spun); Viscose (filament or spun) are the different types of yarn produced so.
Ring Spinning and rotor spinning are two important methods of yarn formation. In spinning the fibers are pulled or twisted into a continuous length
It is at this stage that a twist is introduced into the yarn; this twisting is done to give strength to the yarn – S-twist ( direction of twist is to the left- clockwise) and Z twist (direction of twist is to the right- anticlockwise).
The number of twists per inch can affect the quality of the yarn. More the number of twists, better the yarn.
Single strand yarn – When yarn is made of one strand of twisted fibers . These make fine lightweight and smooth surfaced fabrics.
Ply yarn – Twofold or three fold yarn – Here two or three singles are twisted together. You would have heard of them as 2 ply, 3 ply etc. They make very durable fabrics.
Cabled yarn – Here folded yarns are twisted together – also called four-ply yarn when two strands of two-ply yarns are twisted together.
Other types of fancy yarns like slub, loop, knotted, feather and gimp yarns are also formed.
An elastic stretchy yarn is needed for knitting. For this man-made yarn has to undergo a process called texturing in that the yarn is twisted and heat set and then cooled and untwisted. Air texturing, is another similar process that uses high velocity air instead of heat.
This is done to improve the size of the yarns and to minimize breakages. Sizing is done with polyvinyl alcohol, poly acrylic acid, carboxymethyl cellulose or starch.
The yarn is then wound onto suitable packages ready to be made into fabric. From the skeins or bobbins they are transferred to cones.
If weaving is used to make the fabric, the warp yarns are assembled onto a beam. This process is also called warping.
Weaving / Knitting / making of non wovens
Then the yarn is made into fabric. The 2 main processes are weaving and knitting.
In weaving 2 sets of yarns are interlaced to from the fabric. The fabric is produced by interlacing warp and weft yarns at right angles to each other. In knitting, the loops of yarns are interlaced.
Type of Loom is a very important component in the formation of the woven fabric – the whole appearance of the fabric is changed in the loom. The width of the loom limits width of the cloth. Conventional shuttle looms, rapier looms, and jacquard loom is commonly used. You can find more details on the different types of weaves used in fabric formation here.
Knitting involves forming rows of interlocking loops of yarn and it can be done by hand or special knitting machines. There are circular and flatbed knitting machines which produce different types of knit fabrics
Weft knitting is when successive loops of a single yarn form a row running across the width of the fabric. Warp knitting is when successive loops of yarn run along the length of the fabric.
Single Jersey, Crepe Jersey, Spandex Jersey, Pique Jersey, Interlock, Crepe Interlock, Vertical Stripe Interlock, 2-fold interlock, Pique, Oxford pique, La-coste, Ribs, Spandex rib, Random drop-stitch rib, Feeder rib, French rib, Waffle rib, Pointelle rib are the different types of fabrication involved in knitting.
Non-woven fabrics are produced by following a number of processes like felting, adhesive bonding etc.
This is a process in which cotton fabric/woolen fabrics are prepared for dyeing – the short surface fibers are effectively removed by singeing the surface of the fabric with a gas flame.
Desizing process involves removing the sizing (added to the yarn) by washing the fabric with diluted acid or by enzyme treatment.
Scouring is basically removing the impurities in the fabric by washing the fabric with various chemicals.
Mercerizing is done to increase the strength and luster of fabric. It is a process done with concentrated caustic alkali.
Dyeing can be done at any stage of the production of the fabric -it is usually done at an early stage on yarns or after fabric is made. Actually good quality fabric production involves dyeing at the yarn stage, as the colours will not fade much. When a fabric is not dyed as it comes out of a mill it is called a grey cloth. It is then piece dyed. Different methods like Reactive, Pigment,
Discharge, Burnout, Rotary or Flat Screens are used to dye fabrics.
Fabric finish refers to the techniques used on finished fabric to give it some special characteristics like wrinkle-free finish or stain-free finish or waterproof finish. It may also be added to enhance its characteristics like strength, beauty, etc. Compaction, Brushing, Cropping, Sueding Mercerizing are different types of finishes done on fabric.
You can find more details on different kinds of fabric finishes here.
PS: These are only for those looking for simple answers. For more detailed study on these processes, you may want to refer to the true experts.
Books to refer for detailed study
Textiles : Fiber to Fabric : Bernard P Corbman 1983
Understanding textiles : Billie J. Collier, Martin Bide, Phyllis G. Tortora 2001
Technology of textile properties : Marjorie A Taylor 1990