In this essay we will discuss about the yarn making process of fabrics. After reading this essay you will learn about:- 1. Introduction to the Yarn Making Process 2. Types of Yarns 3. Weaving 4. Types of Weaves 5. Primary Finishes.
Essay # 1. Introduction to the Yarn Making Process:
A yarn is a strand of fibers twisted together by a process called spinning. Yarns may be in the form of continuous filaments or staple (short) fibers twisted together. The quality of the fabric depends upon the quality of yarn. Therefore, the thickness of the yarn, the evenness, cleanliness, strength, elasticity and its twist play an important role in the selection of the yarns for the weaving or spinning of fabrics.
Some years before, the yarns were spun by man with hands. But, as the textile industries are now flourishing all over the world, new techniques and machineries are used for the preparation of yarns. Fine yearns require more twist than coarse yarns. Warp yarns or the threads used lengthwise in weaving are given more twist than the filling yarns, which are used widthwise.
Most of the fabrics are made from yarns with ordinary twist. The short fibers are converted into yarn in terms of basic manufacturing process like carding, combing, drafting, twisting and winding. By passing through these processes the fibers are formed into lap, sliver, roving and finally yarns.
Essay # 2. Types of Yarns:
There are various types of Yarns.
Mainly they are classified into two main groups:
(a) Simple Yarn.
(b) Complex or Novelty Yarns.
A. Simple Yarns:
Only one kind of fiber is used in the construction of simple yarn. The same type of twist is given throughout the length of the yarn. Simple yarns may be single stand, ply, cabled or doubled yarns.
(a) Single strand yarn:
A number of fibers are twisted together into a continuous length to prepare single strand yarn. This yarn consists of one kind of fiber and of one colour.
(b) Ply yarn:
When two or more strands or yams are twisted together, they are known as ply yarn. They may be two ply, three ply, four ply and so on. Ply yarns produce good quality durable fabrics. Generally, filament yarns are not plied.
(c) Cabled yarn:
Two or more plied yarns may be twisted together to form a cabled yarn. The twist may be in the form of S or Z. These yarns are hard, rough and strong.
(d) Doubled yarn:
This is another type of yarn construction. This consists of two or more single strands but are not twisted together. Doubled yarns are used for the production of ornamental effect. Doubled yarns have little twist. They produce lustre and softness.
B. Complex or Novelfy Yarns:
The construction of these yarn is complex in nature. They are constructed by combining yarns of various colours, sizes, thickness and may be twisted together to form one complex yarn.
These are fancy yarns:
(a) Grandrelle yarns:
Two different coloured threads are twisted together to produce this yarn.
(b) Slub yams:
Such yams have soft untwisted areas at frequent intervals throughout the length.
(c) Spiral yarns:
One coarse yarn is wound around a fine yarn and gives the effect of a spiral. Spiral yarns may be made for different purposes. This gives a decorative spiral effect.
(d) Rative yams:
These are variations of spiral yarn type, but the method of manufacture differs. The outer yarn and the core yam are twisted in a spiral manner. The third yarn acts as the binder.
Curl or Loop yarn:
These yarns consists of a fine foundation thread and a soft spun, thick thread which forms loops of intervals, and a fine binder thread.
These are composed of one or two foundation threads which are twisted with a third thread. The third thread at intervals wrapped round the former to produce lumps or knots.
The term chenille is derived from the French for “Cater pillar”. It produces a velvet like or pile surface.
A typical novelty yarn has three basic parts:
1. The ground or foundation (core)
2. The binders.
3. The fancy effect.
Essay # 3. Weaving:
Weaving means interlacing of two sets of materials. From the primitive ages, it was used by man for making baskets, mats, roofs, and walls of huts from leaves, ropes, barks etc. The same principle of weaving is used for the preparation of fabrics. For fabric construction, weaving is the interlacing of two sets of yarns at right angles.
Weaving is largely used method for fabric construction. There are two sets of yarns or threads. While weaving of fabrics, the threads which are placed lengthwise are known as “warp” threads and those which go across are termed “filling or weft” threads. “Warp” and “weft” are the technical terms used in weaving. The warp threads are thicker and stronger than the weft thread. The interlacing of warp and filling threads or weaving is generally done by a machine known as loom.
The following parts are attached to the loom.
i. Beam or Cylinder:
These are known as warp beam. Warp threads are wrapped in Parallel line which is placed at the back of the loom.
This is a frame consisting of a number of wires known as heddles. Harness controls the movement of the warp yarns and help to produce the desired pattern in the cloth.
This holds the filling or weft yarn and is passed forwards and backwards across the loom.
It is a frame which is located directly in front of the harness. It is like a comb. This frame pushes forward each time, the shuttle passes in between the warp yarns. It also presses back the weft thread in position.
The fabric is slowly wound on to the cloth roller in front of the loom. Complicated designs are woven by Jacquard machines.
Essay # 4. Types of Weaves:
The degrees of durability and usefulness of the fabric depend upon the weave patterns. Weave patterns can also change the appearance of the fabric. In a simple weave construction, two harnesses are required, but more than two harnesses are required for advanced weaves. For figure weave nearly forty harnesses are required. In fabric construction, three basic weaves are generally used. These are plain weave, Twill weave and Satin weave. These weaves are the foundation weaves and different types of weaves are made out of these basic weaves, which are known as Novelty weaves.
I. Plain Weave:
This is a simple and basic weave which is relatively inexpensive. It consists of an alternate interlacing of the warp and weft yarn (over one and under the other), along the entire width of the fabric. Plain weave is sometimes called as cotton, taffeta, or tabby weave. Two harnesses are used for this weave. In this weave, one harness is raised which separates the alternate warp yarns to form a shed and then the shuttle carrying the filling yarn is passed through. Next, the lifter harness is lowered and other harness is raised to form a new shed for the return passage of the shuttle.
1. Plain weave is relatively inexpensive method of weaving.
2. Plain weave fabrics have no right or wrong side.
3. It provides a wide scope for introducing variations in the fabric for e.g. seer sucker, flannelettes.
4. Plain weave is made interesting by printing and embossing.
5. Plain weave fabrics has great utility value.
6. Different finishing processes may be used on plain weave fabrics to introduce varieties and styles in fabrics.
7. Plain weave is used in the construction of fabrics from almost all textile yarns cheapest to produce.
8. It is the most serviceable of all the weaves as fabrics with this weave are easy to wash, dry clean, wear well etc.
Rib and Basket weaves are two variations of plain weave.
II. Rib Weave:
In this weave heavier yarns are used in the warp than the weft which produces a ribbed effect. Sometimes the order is reversed, where heavier yarns are used in weft side. The weaving process is same as plain weave that is alternate interlacing of warp and weft thread. Rib can be produced lengthwise or widthwise.
III. Basket Weave:
This weave is also a variation of plain weave. It is a balanced weave. Two or more filling yarns are interlaced with a cores pending number of warp yarns. They are woven in a pattern 2 x 2, 3 x 3, or 4 X 4 instead of 1 X 1. The weaving process is same as plain and filling yarns. Attractive fabrics may be woven. This wave is used in materials for sport coats and suits. The disadvantage of this weave is that this is comparatively loose weave and therefore the fabrics may shrink.
IV. Twill Weave:
This is a basic weave which forms a distinct diagonal design across the face of the cloth. In this weave, there is interlacing of warp and filling yarns with a progression of one at the point of interlacing. In the twill weave the filling yarn interlaces more than one warp yarn, but never more than four. The simplest from of the twill weave is made by throwing the filling yarn over two warp yarns, then under one over two, under one and so on with a progression of one.
The common variation of twill weave is “Herring bone weave”, “Zigzag weave” and “Broken twill weave”.
This is 3/1 twill weave. The warp yarns 2, 3, 4, 6, 7 and 8 are up and warp yarns 1 and 5 are down when the first filling yarn is passed through the warp yarns 1, 3,4,5, 7 and 8 are up and 2 and 6 are down when the second filling yarn is passed through and so on.
1. Twill weave produces strong materials because of the tightly twisted yarns.
2. Though twill weave fabrics are expensive but they stand hard and long wear. They are more durable of all weaves.
3. No dust and dirt are easily attached to twill weave fabrics.
4. Twill weaves are commonly used in man’s suit and coat fabrics where strong construction is essential.
V. Satin Weave:
Satin weave fabrics give a smooth and generally lustrous surface. In this weave the interlacing of warp and filling yarns is irregular. The filling yarn passes under several warp yarns, thus throwing up the warp on the surface, which is called a warp face satin weave. It produces a smooth surface.
1. It creates flat and smooth surface of the fabric.
2. Lustrous effect can be produced by this weave.
3. This is a rich looking fabric.
4. It stands a good deal of hard wear.
VI. Sateen Weave:
Sateen weave is the variation of Satin weave in which filling yarns are thrown up to the surface. In this weave, the filling yarn is passed over several warp warns which is known as filling-faced sateen weave.
VII. Novelty Weaves:
These are the complex weaving patterns. Different designs are also produced by these weaves.
VIII. Figure Weaving:
In this weaving a design is formed by a change in the interlacing of warp and filling yarns.
There are two methods of making this figure weave:
2. Jacquard weave
i. Dobby Weave:
Geometrical designs are formed by this weave. A mechanical attachment called “Dobby” or ‘Cam’ is sufficient for this weave on a plain loom. It consists of a chain of narrow strips of wood hung on the top of the loom. Pegs are inserted in each of the strips to indicate the pattern. These strips of wood control the movement of the harness to form a shed. Another chain of strips of wood controls the shuttle and the design is woven in the fabric. As many as twenty four to forty harnesses containing a series of warp yarns are required which form the pattern.
The most familiar type of dobby weave is:
(a) Bird’s eye,
(c) Honey comb weave, etc.
(a) Birds’ Eye Weave:
In this weave the filling yarns are floating on the surface in such a manner that they produce small diamond shaped designs. The back of the fabric shows the warp yarns over which the filling yarns float. This weave is used in diapers.
(b) Huckaback weave:
In this weave warp yarns are floating on the surface of the fabric. The floating produce short, intermittent lengthwise ridges.
(c) Honey Comb Weave:
In this weave cell like appearance is produced by the floating yarns which form ridges. Here diamond construction is used. Both the warp and the filling yarns float on both the sides of the material in honeycomb weave. This weave is suitable for towels. In this weave, the vertical lines are formed by floating warp yarns and the horizontal lines are formed by the floating of filling yarns.
The designs in the dobby weave are simple, limited in size and usually geometric in form. They are found in shirting’s and tie fabrics. Fabrics made with a dobby weave are generally of spun yarn and of medium weight.
ii. Jacquard Weave:
This weave is constructed in a Jacquard loom because of elaborate designs. The Jacquard loom is extremely complicated and very expensive. The Jacquard loom was invented by a French man Joseph Maris Jacquard in 1801. The Jacquard mechanism controls thousands of heddles. In this loom, every individual warp is controlled independently. Jacquard cards are used to control the raising of the warp yarns. The actual weave is a combination of two or more kinds of fundamental weaves or a variation of such combinations.
IX. Pile Weaving:
The pile weave is a fancy weave which includes a plain or twill weave construction. In this type of weave three sets of yarns are used. Generally, the ground fabric is made by plain or twill weave by two sets of yarns. The third set of yarn makes the loops or the floats on the surface of the fabric.
The loops are drawn away at regular intervals. These loops may be cut either by hand or machinery and brushed up to form the pile. Velvet clothes are the examples where the loops are cut and brushed. Turkish towels are made by this pile weaving construction, where the loops are left uncut. Pile weave is generally used for constructing silk and rayon fabrics. Most pile fabrics are in the medium and heavy weight categories.
1. Pile fabrics in silk are soft to the touch and have a smooth feelings.
2. Closed pile fabrics are strong and has a good weaving quality.
3. Uncut pile fabrics may wear better than cut pile.
4. It is a fancy weave which looks very attractive.
5. Rugs, carpets are made by this weave.
X. Double Weave:
Five or more sets of yarns are used. In this weave two fabrics are woven on the loom at the same time, one on the top of the other. The fabric may have a plain weave in one side and a twill weave on the other. In some fabric two sets of warp and two sets of filling yarns are used. Sometimes one set of warp and two sets of filling yarns are used or vice versa. Double weaving is done to produce a large variety in fabrics.
1. The fabrics constructed by this weave become strong and warm.
2. The fabric may be heavy and bulky.
3. This weave is constructed in cheaper materials reduces the cost of a heavy fabric.
4. The fabrics may be used for robes, blankets, coat materials and upholstery fabrics.
Essay # 5. Primary Finishes:
Fabrics are prepared from the yarns of various fibers. These newly constructed fabrics are very dull and unattractive when they come out of the loom. These are called as “gray goods”. In order to clean them, improve their appearance and prepare them for the market, some final processes are to be given which is known as “Primary Finishes.” A finish is defined as anything to be done to fiber, yam or fabric before or after weaving to change the appearance, improve the quality, texture and to produce variety.
1. To Improve the Appearance and Enhance the Attractiveness of the Fabric:
Fabrics, as they come out of the loom become vary soiled and thereby look dull. Sometimes loose yarns or knots are present on the surface of the fabric after weaving. Cotton fabrics have no shinning appearance and smooth texture. Finishes like napping, raising calendaring and mercerizing can cover the surface defects of the fabric and give smooth texture and shinning appearance to the dull fabrics.
2. To Improve the Utility:
Some fabrics are not quite suitable for dress materials. In order to improve their quality, the fabrics are treated with crease resistant finish and crepe finish. Finishing are also given to resist shrinkage. To improve the quality some fabrics are given water proof, fire proof, and mildew proof finish.
3. To Produce Variety:
Variety in the fabric can be produced by two ways:
(a) By dyeing or printing,
(b) By giving the surface finishing as napping, beetling, creeping and smooth finish.
4. To Produce Imitation:
Some finishing process is given to fabric in order to change the original appearance and to produce imitation. Cotton has no shinning appearance. By the application of mercerization, the dullness is removed and cotton gets smooth, shinning appearance like silk fabrics. Napping finishing can give the fabric napped appearance like wool.
5. To Increase the Weight and Stiffness:
Finishes can increase the weight and stiffness of the fabrics. Gray goods must be cleaned before they can be finished. Complete removal of knots, wrap, loose yarns, sizing, oils, dirt and soil is necessary. The method of cleaning depends upon the fiber in the fabric, the kind of impurities present and the construction of fabric.
There are so many finishing processes, but all cannot be used in all types of fabrics. It depends upon the nature of the fiber, the type of yarn and the kinds of weaves. Most of the simple finishing process consists of the application of pressure moisture and heat. Finishing may be given in the mills or at special centers called “converters”.
Primary finishes may be broadly classified into:
(1) Mechanized finishes.
(2) Chemical finishes.
1. Mechanical Finishing Processes:
Mechanical finishes cause physical changes of the fabric. Different machineries are used for this finish and it is only temporary finishing process.
Beetling is a common finishing process for cotton and linen. Beetling was originally done by beating the surface with wooden hammers by hand. But now machineries are used. A number of wooden or steel hammers are attached to the machine. When the machine rotates, the hammers rise and fall on the surface of the cloth. By this finish, the weaves are closed, fibers are flattened and lustrous effect is produced. Cotton and Linen have smoothness and shinning appearance after this finishing process.
Small fibers and loose end of the fibers which stick to the surface of the fabric are removed by this finish. There are two roller brushes. The fabric is passed in between these two rollers which brushes up both the sides of the material at a time.
Shearing is a mechanical finishing process by which the fiber ends are cut or trimmed from the surface of the fabric. This is used on all clothes except napped fabrics and blankets. For pile and napped fabrics shearing finishing is given to obtain the length of the nap desired or to even the naps. This finish gives the pile fabrics, a smooth surface. This finish is given by a machine with rotating cylinders having spiral blades. It acts as the Lawn Mower. After shearing, the fabric is automatically brushed to remove the ends of yams.
Calendaring process is the final process. The fabric is passed between very hot and highly polished rollers. This produces glazed finish and smooth even surface to the fabrics. Woolen fabrics are sometimes calendared or polished. This process adds a lustre and shinning appearance to the fabric when repeated several times. The polyester fabrics acquire a soft attractive look after this finishing process. This is also a final finish for cotton, rayon, linen and silk fabrics.
In order to produce a raised effect, napping finish is given. For this finish, the fabric is passed over a revolving cylinder covered with teasels and short bent wires. The teasels or wire hooks scrape the surface of the fabric, pulling up fiber and out of the yarn, so as to form a nap.
The nap is then clipped to uniform size by passing through the shearing machine. The thicker the nap, the warmer becomes to fabric. Napping finishing gives soft and pleasing feel. It also covers up defects if any on the surface of the fabric. Cottons and woolens are finished by this process.
The finishing process is applied at various stages of finishing. After dyeing or wet finishing process the fabric gets uneven edges. These edges are becoming even by tentering finishing process. There is a tantering frame, consisting of two endless chains in two sides. There are some clips or pins attached to the chains which grip the selvedge of the fabric.
It controls the pulling process for straightening out the fabric placed on the tantering frame. Steam coils are arranged under the frame which dries the fabric during the process of stretching. This process is used on silk, cotton, rayon and Linen fabrics.
Raised figures or designs are produced on the surface of the fabric by embossing finishes. This finishing is given to all types of fibers except wool. It becomes permanent finish when applied to thermoplastic fibers. This is done by a separate machine which consists of two rollers. One of these rollers is covered with cloth and another is engraved with a particular design. The cloth covering roller is moistened with soapy water.
When the machine operates, the impression of the design is taken on the cloth covered roller. This means both the rollers have now the same design or pattern. Both these rollers are heated with steam and the fabric is passed in between these two rollers.
As the machine rotates, the design is imprinted on both the sides of the fabric at a time, one side from the cloth covered roller and the other from the engraved roller. To preserve the embossed finish in non-thermoplastic fabrics, they should be washed in Luke warm water with a mild soap.
A glazed surface can be obtained by the application of this finish. For this finishing process the fabric is to be stiffened with sizing first. The machine consists of three rollers. The middle roller is covered with a cloth. The fabric is passed in between the first two rollers and then under the third which rotates at a greater speed. This gives shinning appearance to the fabric. This finishing process makes the fabric resistant to dust and dirt and minimizes shrinkage.
This process is generally given to cotton fabrics. Cotton fabrics are stiffened with china cloy, chalk, barium, sulfate, calcium, sulfate, magnesium sulfate, chloride etc. In addition to starch, soluble oils and fats are often used to modify stiffness of the starch. Sizing solution is made out of these things.
There are two rollers heated with steam. The fabric is passed between these rollers. One of the rollers is continuously covered with sizing solution which dropped on to the fabric in a regulated stream. Addition to paraffin, glycerin or oil to the sizing solution will produce softness in the fabric. Wax may also be added to give a glossy surface with lustrous effect. Cotton fabrics that are usually sized are organdy, lawn, voile and buckram.
This finish is given to wool and silk. The agents used are metabolic salt. The weight of the body of the fabric is increased by immersing it in a solution containing metabolic salts. The salts penetrate the yarn and become a permanent part of the fabric.
Silk may be treated with tin salt either at the yarn stage or in woven fabric. It is also weighted during the process of dyeing. But heavily weighted silk has a poor wearing quality. Wool is weighted with magnesium chloride. So that the cloth absorbs more moisture and the weight is increased. Only low grade wool fibers are weighted.
This is an expensive method of finishing process. Low priced cotton may be given this finishes to increase the lusture. Steam rollers having thousands of engraved diagonal lines are used for this finish. When the fabric is pressed in between these rollers reflection of light from their ridges gives the fabric a lustrous effect. But it is not a permanent finishing process.
xii. Crepe Effect:
For this finish, the fabric is passed between two rollers. The rollers have regular indentations at regular intervals which produce the crepe effect on the fabric.
2. Chemical Finish:
Chemical finish is a permanent finishing process. Chemical reagents are applied to the fabric. By this finish, the original appearance or the characteristic properties of the fabrics are changed.
Some of the important chemical finishing processes fabric are listed below:
This is an important finishing process given to cotton. It gives a lustrous effect to cotton fabric. This process was first discovered by John Mercer, a calico printer of England in the year 1844. This finish is named after him. Mercerization process consists of passing the fabric through a cold 15 to 20% solution of caustic soda.
It is then stretched out on a Tenter Frame where hot water is sprayed to remove most of the caustic sode. This process is applied to reduce shrinkage and to increase lustre. It gives a smooth and silky affect to cotton fiber. Mercerization is a permanent finishing process.
II. Crepe and Crinkled Effect:
Crepes effects produced by the use of chemicals are more permanent than mechanical finishing process. Caustic soda paste is applied to the fabric in a definite design or figures. The part to which this paste is applied shrinks leaving the other parts un-shrunk. Thus a crepe or crinkled effect is produced on the surface of the fabric.
A similar effect is obtained by using strips of wax in place of the caustic sode. A crepe effect on the silk fabric may be produced by treating the fabric with concentrated sulfuric acid for a few minutes. It is then rinsed and neutralized with a weak alkali. But there is a decrease in lustre and strength when this finish is applied to silk fabrics.
III. Crease Resistant Finish:
This is known as Resin treatment to the fabric. Owing to the natural inelasticity, wrinkles are formed on cotton fabrics. So this finish is given to avoid crease or wrinkles. In this finishing process the fabric is treated with a solution of synthetic resin prepared from phenol formaldehyde, Urea formal dehyde and acrylic resins. Then the fabric is dried by a high temperature in a moist atmosphere. This finish improves the resilience of the fiber. Shrinkage on wool fabrics may be controlled by treating it with certain thermosetting resins.
IV. Fire Proof Finish:
Generally, the mineral fibers are flame proof. But other fibers are inflammable. Fire proof finish is given to the fabric, so that they cannot catch fire easily. A simple method is the treatment with boric acid and borax. But this is a temporary process which dissolves in water. For permanent effect, the fabric is treated with Vinyl Chloride or Chlorinated rubber and Antimony oxide. This solution covers the fabric with a thin noninflammable film which makes the fabric fire proof.
V. Moth Proof Finish:
In this finish, calcium chloride and silica gel are used. The fabric is treated with a solution of calcium chloride to provide this finish.
VI. Water Proof Finish:
In this finishing process the fabric is treated with wax emulsions metallic soap and other surface active agents. This helps in resistance to water penetration in the fabric.