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Tuesday 26 January 2010

Care of your cotton garment

Cotton:
Cotton is a soft white fibrous substance covering seeds of certain plants.

CHARACTERISTICS OF COTTON:
Cotton, as a natural cellulosic fiber, has a lot of characteristics, such as;
  • Comfortable Soft hand
  • Good absorbency
  • Color retention
  • Prints well
  • Machine-washable
  • Dry-cleanable
  • Good strength
  • Drapes well
  • Easy to handle and sew

For fabrics made of 100% cotton:
  1. Set your washing machine to the low setting.
  2. Wash the cloth in cold water.
  3. Set your iron to Medium to iron it.
  4. Do not bleach the cloth.
  5. Hang to dry but do not tumble dry.

50% Cotton and 50% Polyester:
  1. Turn it inside out and machine wash with warm water.
  2. Wash with fabrics that are of light colours.
  3. Use only non-chlorine bleach to bleach the cloth.
  4. Tumble dry with a medium setting.
  5. Set your iron to medium for ironing.

Properties of the cotton:
  1. It is soft and comfortable.
  2. It wrinkles easily.
  3. It absorbs perspiration quickly.
  4. It has good colour retention and is good to print on.
  5. Cotton is also strong and durable.

Uses:
Cotton is used to make blouses, shirts, singlets, shorts, bermudas, jackets and pants. It can also be made into bedspreads, pillowcases, carpets and curtains.

Thursday 21 January 2010

TYPES OF FANCY YARN


Slub yarns
  • Slub yarn is charactorised by having, alternating short places of thin, firm twist yarn, with places of very thick, loose twist yarn
  • The differnt areas can be at regular or irregular intervals

Knop or button yarns
  • These yarns are also made by feeding the yarns at different rates while spinning
  • But this time the excess yarn of one or more of the components forms bunches
  • These can be at regular or irregular intervals

Snarl yarns
  • Snarl yarns are made in a similar way to loop yarns
  • Except the effect yarn has a high, lively twist, so that the excess bits snarl and double up on themselves and twist together
  • (Just like the lengths of cord we make on a door-knob!)

Boucle, gimp and loop yarns
  • These yarns are made by feeding one or more effect yarns faster than the core yarn while spinnin
  • boucle has a hard twisted core yarn, the effect yarn is rapidly twisted round the core so that excess yarn forms an irregular wavy, bumpy surface
  • gimp is much the same as boucle, but the excess yarn forms a more regular surface
  • loop yarn is the result of the excess soft spun yarn being formed into well shaped circular



Marl yarns

  • Marl yarns are made by twistng together two or more ends of different coloured yarns
  • The effect pattern is one of regular diagonal stripes of each colour

Spiral and corkscrew yarns
  • These are plied yarns where one yarn wraps around the other, rather than the yarns being twisted together
  • A spiral yarn has a higher twist than a corkscrew yarn
  • A spiral yarn usually has a thinner yarn wrapped round a thicker core
  • A corkscrew yarn has a softer bulkyer yarn wrapped round a thin, firm yarn

Chenille yarns
  • chenille yarns have a soft, fuzzy cut pile which is bound to a core
  • These yarns can be spun, but the machinery required is very specialised For this reason, these yarns are usually woven on a loom
  • The effect yarn forms the warp, which is bound by a weft thread
  • The weft thread is spaced out at a distance of twice the required length of pile
  • The warp is then cut half way between each weft thread.

Ribbon yarns
  • These yarns are not produced by spinning
  • They are finely knitted tubes, pressed flat to resemble ribbon or tape
  • The ribbons are usually soft, shiny and silky

Tuesday 19 January 2010

Cotton Harvesting


Cotton is harvested either by hand or machine. Countries like China, India and West Africa still rely heavily on hand picking. Other countries like the United States and Australia are mostly machine harvested. The two methods of machine harvesting are spindle or stripper.

Hand harvesting commences as the bottom bolls open, whilst the plant is still green and will continue until the top bolls open. It can take up to three months to compete the hand harvesting process as it is usually done in three to four stages. Hand harvesting is a much longer process and requires extensive labour resources. Cotton that is hand harvested is normally free of trash prior to be ginnned.


Machine pickers harvest cotton from open bolls whilst the plant has been defiolated and leave unopened bolls and empty bolls on the plant. This is accomplished by revolving spindles that pluck the fiber out of the boll. Machine strippers strip the entire plant of opened and unopened bolls. The fiber removed from the plant also contains the cotton seeds and is referred to as seed cotton. After harvesting, the seed cotton is transported to the gin.

Cotton Production

Cotton is an annual field crop that is grown in a wide variety of regions. The largest areas of production are China, USA, CIS, West Africa and Brazil. Cotton, as a plant, generally requires large amounts of sunshine, but is prone to insect infestations and damage. Substantial inputs are required to produce the crop, making it one of the most capital intensive field crops.

New seed types have reduced the growing season and improved fiber characteristics, somewhat reducing the risks involved. Cotton is generally part of a crop rotation with soybeans and can sometimes be included in a crop rotation with corn.

Wet Spinning


Spinning is an ancient textile art in which plant, animal or synthetic fibers are twisted together to form yarn. For thousands of years, fiber was spun by hand using simple tools, the spindle and distaff. Only in the High Middle Ages did the spinning wheel increase the output of individual spinners, and mass-production only arose in the 18th century with the beginnings of the Industrial Revolution. Hand-spinning remains a popular handicraft.

There are mainly 3 types of spinning process:
  1. Melt spinning
  2. Dry spinning
  3. Wet spinning

Wet Spinning: Wet spinning is the oldest process. It is used for fiber-forming substances that have been dissolved in a solvent. The spinnerets are submerged in a chemical bath and as the filaments emerge they precipitate from solution and solidify. Because the solution is extruded directly into the precipitating liquid, this process for making fibers is called wet spinning. Acrylic, rayon, aramid, modacrylic and spandex can be produced by this process. In another way we also say that, Wet solvent spinning. Wet spinning also uses solvent to dissolve the polymer to prepare the spinning dope. The process begins by dissolving polymer chips in a suitable organic solvent, such as dimethylformamide (DMF), dimethylacetamide (DMAc), or acetone, as in dry spinning; or in a weak inorganic acid, such as zinc chloride or aqueous sodium thiocyanate. In wet spinning, the spinning solution is extruded through spinneret’s into a precipitation bath that contains a coagulant (or precipitant) such as aqueous DMAc or water. Precipitation or coagulation occurs by diffusion of the solvent out of the thread and by diffusion of the coagulant into the thread. Wet spun filaments also undergo one or more of the additional treatment processes described earlier, as depicted in Figure.


Figure: Wet spinning method

Air pollution emission points in the wet spinning organic solvent process are similar to those (Figure)Wet spinning. Wet spinning processes that use solutions of acids or salts to dissolve the polymer chips emit no solvent VOC, only unreacted monomer, and are, therefore, relatively clean from an air pollution standpoint. For those that require solvent, emissions occur as solvent evaporates from the spinning bath and from the fiber in post-spinning operations.

Application: Wet spinning is used for viscose, cellulose & some synthetic fibers, like poly acrylonitrile (PAN) from salt solution. This process is also used to produce Acrylic, rayon, aramid, modacrylic and spandex .
Below figure shows the step of this process-








Unit Conversion

Unit Conversion

Length

1 in

=

2.54 cm

=

0.0254 m

1 ft

=

30.48 cm

=

0.3048 m

1 yard

=

91.44 cm

=

0.9144 m

1 mile

=

1.6093 Km

=

1609.3 m



Area

1 in2

=

6.4516 cm2

1 ft2

=

0.0929 m2

1 acre

=

0.4047 hectares

=

4047 m2

Volume

1 in3

=

16.387 cm3

1 ft3

=

0.0283 m3

1 us f.oz

=

29.574 ml

1 imp f.oz

=

28.41 ml

1 us gal

=

3.7854 l

1 imp gal

=

4.546 l



Weight

1 OZ

=

28.35 g

1 lb

=

0.4536 kg

=

453.6 g

1 imp ton

=

1016 kg



Temperature

oF

=

oC*1.8 + 32

oC

=

(oF - 32) / 1.8

oR

=

oF + 459.67

K

=

oC + 273.15

Saturday 9 January 2010

Weaving operation

Fabric Construction
Textiles are important for everyone. It is used for covering body, for warmth or coolness, personality enhancement and sometimes to display one's status in the society. From the wholesale textile manufacturer and merchant to the retailer and the end- user, the customer, everyone consumes textile. Not only those who are in this direct trade are related to this product but there are certain industries which are indirectly associated with textile. Automobile industry is a good example of this type of industry which uses textile in various forms. Others who use textile in one or the other form may include designers, interior decorators, craftspersons, advertisers using hoardings and banners, painters etc


Weaving operations
Four major operations are involved in weaving- Shedding, Picking, Beating up (Battening) and Taking up and letting off.

Shedding
Each alternate warp yarn is raised to insert the filling yarn into the warp to form a shed.

Picking
As the warp is raised, the filling yarn is inserted through the shed by a carrier device. Different types of looms are used for carrying the filling yarn through the shed- Shuttle loom, shuttle less looms, circular looms etc.

Beating up (Battening)
With each picking operation, the reed pushes or beats each filling yarn against the portion of the fabric that has already been formed. Reed is a comb like structure attached to the looms. It gives the fabric a firm, compact construction.

Taking up and letting off
With each shedding,Picking, Battening operation, the new fabric must be wound on the cloth beam which is called 'taking up'. At the same time, the warp yarns must be released from the warp beam which is called l 'letting off'.

As the shuttle moves back and forth across the width of the shed, a self edge is woven which is called selvage or selvedge. The selvage prevents the fabric from muddling. It is usually more compact and strong than the rest of the fabric. There are different kinds of selvages depending upon the expected use of the fabric- Plain Selvages, Tape Selvages, Split Selvages, Fused Selvages, Leno Selvages and Tucked Selvages.