Friday, 23 April 2010

How to crinkle a Fabric



In the basic process, the fabric is soaked in water. It is then twisted into the form of tight rope. It is then again twisted in on itself until becoming basically a ball of twisted fabric. The ends are tucked in so the fabric doesn't come untwisted. Then it is dried using microwave or other means. It is not recommended that the damp twisted fabric ball be left overnight otherwise it will mildew.

This is an amazing article on how to crinkle a fabric.

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Sunday, 11 April 2010

What is the difference among Mulberry, Tussar ( Tasar), Muga and ERI Silk



The difference is in the type of worms producing the yarn and the types of leaves they eat.

Mulberry Silk is obtained from BOMBYX MORI feeding on MULBERRY leaves.


Tussar Silk is obtained from ANTHEREA MYLITTA feeding on ARJUN and ASAN leaves.


Muga Silk is obtained from ANTHEREA ASSAMENSIS feeding on SOM and SUALU leaves.

Eri Silk is obtained from CYNTHIA RICINI  feeding on CASTOR OIL leaves.

The eri silk worm is the only completely domesticated silkworm other than Bombyx mori.

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Spinning Mills Vs. Garment Sector: Who will bear the Burden



This Article is related to Textile Industry in India

With the rising cotton yarn prices, the garment manufacturers are feeling the heat. Unable to pass on the price hike to the customers, they are turning back to the government for relief. The government has done its part by the following measures:

1. Government has withdrawn 7.67 percent DEPB Benefits for cotton yarn exports.

2. It has also introduced a cess on export of cotton yarn.

This step is take with the following assumptions:

a. Cotton yarn prices have increased because of rising export demands.

b. It is hampering the domestic garment producers and exporters.

c. While domestic markets are able to absorb the increased cost, recession hit West is unable to.

d. It is difficult to pass on the price increase to the customers.


But Will it lead to desirable results

Arguments against

a.  Social Argument: Spinning mills in the country have suffered huge losses during the last two years. They need to make some profits this year.

b. The problem could be solved by giving more assistance to the garment exports to absorb thee additional costs.

c. Less than 20% of cotton yarn produced get exported. Total exports of cotton yarn this year are less than that of last year.

d. The cut in DEPB will not affect much as long as the  global markets are able to absorb the additional costs.

e. The problem can also be solved by improving production efficiencies in Garment manufacturing units so that they can absorb the high yarn prices without passing them on to the customer.

f. It is not only raw-material prices that have gone up. Labor cost and power cost have also increased.

Arguments in Favour

a. In Tirupur, there is an 11% drop in shipments over last year of knitted fabrics.

b. Spinning mills have jacked up cotton yarn prices disproportionately vis-a-vis input costs. Thus eg. raw material prices have risen by 1.79%, but yarn prices have gone up by more than 10%.

What is your opinion ? Write your comments 


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Thursday, 8 April 2010

Principle of Soft Flow Dyeing Machine



Textile material can be dyed using batch, continuous or semi continuous process.

Batch processes are the most common method used to dye textile materials. There are three general types of batch dyeing machines:
  1. In which fabric is circulated
  2. In which dye bath is circulated
  3.  In which both the bath and material is circulated.
Jet dyeing is the best example of a machine that circulated both the fabric and the dyebath. Jet dyeing is used for knitted fabrics. For Terry-towels soft flow dyeing is use.

In jet dyeing machine the fabric is transported by a high speed jet of dye liquid.

As seen in the figure, this pressure is created by venturi. A powerful pump circulates the dyed bath through a heat exchanger and the cloth chamber. Cloth guide tube helps in circulation of fabric.



The vigorous agitation of fabric and dye formulation in the cloth increases the dyeing rate and uniformity. It minimizes creasing as the fabric is not held in any one configuration for very long.  The lower liquor ration allows shorter dye cycles and saves chemicals and energy.

In soft flow dyeing machines the fabric is transported by a stream of dye liquor. However, the transport is 
assisted by a driven lifter reel.

These machines use a jet having lower velocity that that used on conventional jet dyeing machines.

The soft flow machines are more gentle on the fabric than conventional jet machines.

The following are the features of a soft flow U-Type dyeing machine offered by Taxfab:

1. Machine pressure vessel and major wet parts made of stainless steel AISI 316/ 316 L, highly corrosion resistance material.

2. Heavy duty stainless steel centrifugal pump for optional dye liquor circulation. Highly efficient heat exchanger for fast heating and cooling. 

3.  A stainless steel filtering device placed in such a way for easy cleaning. 

4.   A unique design of jet nozzle can provide high discharge of liquore with subsequent pressure to ensure fast movement of fabric transport upto 300 Mtrs / Min., and the speed of fabric can be adjusted, required to desire quality. 

5. A mirror polished fabric transport perforated basket for easy trouble free movement of fabric from back to the front of machine, perforated basket fabricated in such a way that welding part does not come in contact with fabric.

6. For preparing chemical, colour kitchen tank is provided made out of stainless steel 316, with required valves for auto dozing. 

7. All valves is made of investment casting and is of stainless steel 3l6.

8.Electrical control panel with microprocessor to operate the machine is provided with pneumatic control circuits.

9. Magnetic level indicator duly calibrated for correct liquor measurement. 

10.       Take off reel with direct couple geared motor and stainless steel structure 

11. All safety device required for a pressure vessel is incorporated with the machine.

A front view and side of the machine offered by them is as given below:





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Tuesday, 6 April 2010

Textile Testing for a Home Linen Product



Textile Testing is not something that is to be done on a finished product alone. There is a need to measure the effectiveness of each process so that necessary corrections can be done if needed. As an example, for a home linen fabric, the following testing procedures need to be carried out after every process.

Process of Manufacturing a Home-Linen Product

A typical home linen product is manufactured by the following process

Grey Fabric à Singeing and Desizing à Continuous Bleaching à Chainless Mercerisation à Continuous Dyeing range including Pad Dry and Pad Steam à Auto Jiggers with 20 cylinder drying range and open Stenterà Flat Bed Printingà Rotary Printing machine including loop stenter and polymeriser à stenterà Compressive Shrinkageà Calendering à Stitchingà Folding & Packing and Dispatch

The Following Testing procedures are needed at each stage of the process:

1.       Grey inspection and checking

Every supply of grey cloth needs a thorough check for quality of the material. The following checks need to be made

Checking of damage made during the transit
Checking of quantity supplied
Checking of count, reed and pick
Checking of GSM of the cloth
Checking of width of the grey
Checking of knots in every meter of grey
Checking of any deformity of construction of grey
Checking of any unusual cuts in the cloth

2.       Singeing and Scouring

After passing through the Singeing and Scouring process, the fabric undergoes the pilling test to determine the pilling and fuzzing characteristics of the fabric. Thereafter another test is conducted to determine the abrasion and pilling resistance of the fabric. If thesample fails this test as per specifications provided by the buyer then the grey cloth is sent back for Singeing.

3.       Desizing

De-sizing is the next step after which the TEGAWA test is conducted in a lab to check the presence of starch and other substances in the grey cloth and in the event the material fails this test then it is required to undergo the process of De-sizing.

4.       Bleaching

The absorbency test, whiteness test and ph testing are carried out in the lab after completion of the processes of bleaching, washing and drying.

5.       Mercerisation

Subsequent to the Mercerizing process the fabric undergoes ph testing and TWEDDEL and Barium tests to check the concentration of caustic in the fabric. The operation is repeated in case the fabric fails the tests.

6.       Dyeing

Post completion of the dyeing process, a number of tests are carried out to test the colour matching of the sample as per the buyer’s demand and colour fasteness of the cloth. The dyeing process has to be repeated in the event the fabric fails these tests.

7.       Printing

After completion of printing on the fabric, the tests relating to colour matching and fastness are carried out once again.

8.       Stenting

Once the Stenting process is completed, lab tests are conducted for carrying out the shrinkage tests, tensile strengths and tear strengths of the fabric.


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Thursday, 1 April 2010

Common Knit Fabrics



Common Knit Fabrics: A Practical Guide to Yarn Count, GSM and Fabric Structure

Knitted fabrics are among the most widely used fabrics in garments because they are comfortable, stretchable, flexible and suitable for body movement. T-shirts, polos, leggings, sweatshirts, thermals, innerwear, sportswear and many casual garments are made from different types of knit fabrics.

For a merchandiser, designer, buyer or textile student, it is not enough to know only the fabric name. One should also understand the relationship between yarn count, GSM, fabric structure, stretch, handle and end use.

Simple idea: In knit fabrics, yarns are converted into intermeshing loops. The shape, density and arrangement of these loops decide whether the fabric behaves like jersey, rib, interlock, pique, terry, fleece, waffle or thermal fabric.



1. What Makes Knit Fabrics Different from Woven Fabrics?

In woven fabrics, two sets of yarns — warp and weft — interlace with each other. In knitted fabrics, yarns form loops. These loops give knitted fabrics their natural stretch and flexibility.

The two important loop directions in weft-knitted fabrics are:

  • Wales: vertical columns of loops.
  • Courses: horizontal rows of loops.

The density of knitted fabric is often understood through courses per inch and wales per inch. A useful relationship is:

\[ \text{Stitch Density} = \text{Courses per inch} \times \text{Wales per inch} \]

Higher stitch density generally gives a more compact, stable and better-quality fabric, although it may reduce openness, air permeability and softness depending on yarn and finish.

2. GSM and Yarn Count in Knit Fabrics

GSM means grams per square metre. It tells us the weight of the fabric. In general, for the same fabric structure, a coarser yarn count gives a heavier GSM, and a finer yarn count gives a lighter GSM.

For example, in cotton single jersey:

  • 40s cotton yarn may give a light fabric around 100–120 GSM.
  • 30s cotton yarn may give a medium fabric around 140–155 GSM.
  • 20s cotton yarn may give a heavier fabric around 180–200 GSM.
  • 16s cotton yarn may give a heavy fabric around 230–250 GSM.
Technical point: GSM is not controlled by yarn count alone. It is also affected by loop length, machine gauge, stitch density, finishing, relaxation, compacting and shrinkage control.



3. Common Knit Fabrics and Their Uses

Fabric Type Typical Structure General Handle / Behaviour Common Uses
Single Jersey Single-knit structure with face and back clearly different Light, flexible, curls at edges, good drape T-shirts, tops, nightwear, casualwear
Slub Jersey Jersey made with slub yarn Irregular texture, casual look, uneven thick-thin effect Fashion T-shirts, casual tops
Cotton/Spandex Jersey Jersey with elastane/spandex plating Stretchable, better recovery, close fit Leggings, fitted tops, sportswear, innerwear
Pique Textured knit with small raised cellular or honeycomb effect More structured than jersey, breathable, slightly firm Polo shirts, sports-casual garments
1x1 Rib Alternate knit and purl wales High widthwise stretch and recovery Neck ribs, cuffs, waistbands, fitted garments
2x2 Rib Two knit wales followed by two purl wales Bulkier and more pronounced rib effect Cuffs, trims, sweaters, body-fit garments
Interlock Double-knit structure derived from rib Smooth on both sides, stable, thicker, less curling Premium T-shirts, babywear, innerwear, uniforms
Loop Back Terry Back side has uncut loops Absorbent, soft, heavier than jersey Sweatshirts, joggers, hoodies, loungewear
Brushed Back Terry / Fleece Terry back is brushed to raise fibres Warm, soft, bulky, insulating Winter sweatshirts, hoodies, tracksuits
French Terry Looped back, usually smoother and lighter than fleece Comfortable, absorbent, medium warmth Premium casualwear, sweatshirts, athleisure
Waffle Knit Raised square or honeycomb-like texture Textured, absorbent, thermal pockets Thermal tops, towels, robes, casualwear
Thermal Knit Cellular structure designed to trap air Warm, insulating, textured Winter innerwear, base layers

4. Common GSM Ranges for Cotton Knit Fabrics



The following table gives broad industry-style reference ranges. Actual GSM may vary depending on machine settings, yarn quality, finishing and fabric relaxation.

Content Yarn Count Fabric Type Approx. GSM Range
100% Cotton40s CombedSingle Jersey100–120
100% Cotton36s CombedSingle Jersey110–130
100% Cotton30s CombedSingle Jersey140–155
100% Cotton26s CombedSingle Jersey160–170
100% Cotton24s CombedSingle Jersey165–180
100% Cotton20s CombedSingle Jersey180–200
100% Cotton18s CombedSingle Jersey210–230
100% Cotton16s CombedSingle Jersey230–250
95/5 Cotton/Spandex40s + 20DSingle Jersey160–180
95/5 Cotton/Spandex32s + 20DSingle Jersey190–200
95/5 Cotton/Spandex30s + 20DSingle Jersey200–210
95/5 Cotton/Spandex30s + 30DSingle Jersey220–230
100% Cotton30s CombedPique180–190
100% Cotton26s CombedPique190–200
100% Cotton24s CombedPique200–220
100% Cotton20s CombedPique210–240
100% Cotton18s CombedPique240–250
100% Cotton16s CombedPique260–280
100% Cotton40s Combed1x1 Rib140–160
100% Cotton30s Combed1x1 Rib180–200
100% Cotton24s Combed1x1 Rib220–240
100% Cotton20s Combed1x1 Rib250–270
100% Cotton16s Combed1x1 Rib300–340
100% Cotton40s CombedInterlock180–200
100% Cotton30s CombedInterlock220–240
100% Cotton26s CombedInterlock240–260
100% Cotton24s CombedInterlock270–280
100% Cotton20s CombedInterlock300–320
100% Cotton16s CombedInterlock330–350
100% Cotton30s CombedLoop Back Terry180–200
100% Cotton24s CombedLoop Back Terry220–230
100% Cotton20s CombedLoop Back Terry240–260
100% Cotton16s CombedLoop Back Terry280–290
95/5 Cotton/Spandex30sFrench Terry240–260
80/20 Cotton/Poly30s + 10s PC3-End Fleece300–340
80/20 Cotton/Poly20s + 10s PC2-End Fleece260–300
100% Cotton40s CombedWaffle / Thermal140–160
100% Cotton30s CombedWaffle / Thermal180–200
100% Cotton20s CombedWaffle / Thermal250–270
100% Cotton16s CombedWaffle / Thermal300–340

5. How to Identify Jersey, Rib and Interlock Fabric



Single Jersey

Single jersey has a clear face and back. The face side shows vertical wales, while the back side shows a different loop appearance. It curls easily at the edges. When cut, it may curl towards the face or back depending on the direction of cut.

Rib

Rib fabrics show alternate face and reverse wales. They stretch strongly in the width direction. This is why rib fabrics are used for cuffs, collars, neckbands and waistbands. A 1x1 rib has one face wale and one reverse wale alternately. A 2x2 rib has two face wales and two reverse wales alternately.

Interlock

Interlock is a double-knit structure. It is usually smoother and more stable than single jersey. Both sides may look similar, and the fabric is thicker and less prone to curling. It is commonly used in babywear, innerwear, premium T-shirts and garments where better dimensional stability is required.

6. Pique Fabric

Pique is commonly used for polo shirts. It has a textured surface, often with a small honeycomb or cellular appearance. Compared with single jersey, pique usually feels more structured and slightly thicker. It allows better air circulation because of its textured construction.

A cotton pique polo shirt is therefore often preferred where the garment needs more body than a regular T-shirt but should still remain comfortable.

7. Terry, French Terry and Fleece

Terry fabrics have looped yarns on the back side. These loops improve absorbency and bulk. In loop back terry, the loops remain visible. In brushed back terry or fleece, the loops are brushed to create a soft, raised, warm surface.

French terry generally has a smoother face and looped back. It is used in sweatshirts, joggers and athleisure garments where the fabric should be comfortable but not as bulky as heavy winter fleece.

8. Two-End Fleece and Three-End Fleece

Fleece fabrics may be produced as two-end or three-end constructions. In simple terms:

  • Two-end fleece generally uses two yarn systems.
  • Three-end fleece uses three yarn systems and can give better fabric body, stability and surface quality.

Three-end fleece is generally considered a higher-quality construction because it can offer a better face, more stable structure and better print surface. However, it is also more expensive to produce because it uses more yarn and often requires finer yarns to maintain the required GSM and stitch density.

9. Waffle and Thermal Knits

Waffle knit has a raised, square or honeycomb-like texture. The structure can trap air in small pockets, giving a warmer feel. Thermal knits are also designed to trap air and provide insulation. These fabrics are used in winter innerwear, base layers, robes and comfort garments.

10. Why Spandex Changes the GSM

When spandex is added to cotton knit fabrics, the GSM often increases. This is because elastane adds mass and also changes the compactness of the structure. A 95/5 cotton/spandex single jersey fabric made with 30s cotton and 20D or 30D spandex can be much heavier than a 100% cotton single jersey made from the same cotton count.

Spandex also improves:

  • stretch,
  • recovery,
  • fit,
  • shape retention,
  • comfort in body-hugging garments.

11. Practical Selection Guide for Merchandisers and Designers

End Use Suggested Fabric Typical GSM Direction Reason
Light summer T-shirt Single Jersey 120–160 GSM Light, soft, breathable
Premium T-shirt Interlock or heavier Single Jersey 180–240 GSM Better body and stability
Polo shirt Pique 180–240 GSM Textured, structured, breathable
Leggings / fitted tops Cotton/Spandex Jersey or Rib 180–260 GSM Stretch and recovery
Cuffs / neck ribs 1x1 or 2x2 Rib As per garment requirement High stretch and recovery
Sweatshirt French Terry or Fleece 240–340 GSM Bulk, comfort and warmth
Winter innerwear Thermal / Waffle Knit 180–300 GSM Air-trapping structure

12. Important Quality Points in Knit Fabrics

While selecting or approving a knit fabric, the following points should be checked:

  • GSM: whether it matches the buyer’s specification.
  • Width: whether usable width is suitable for marker planning.
  • Shrinkage: both lengthwise and widthwise shrinkage after washing.
  • Spirality: especially important in single jersey fabrics.
  • Stretch and recovery: especially for spandex fabrics.
  • Fabric appearance: slubs, holes, needle lines, barre, shade variation.
  • Hand feel: softness, compactness, bulk and drape.
  • Colour fastness: washing, rubbing, perspiration and light fastness.
Buyer’s checklist: A fabric name alone is not a sufficient specification. A proper knit fabric specification should mention fibre content, yarn count, fabric structure, GSM, width, shrinkage, colour, finishing, stretch requirement and end use.

13. Conclusion

Knit fabrics are simple to wear but technically rich to understand. A single jersey, rib, interlock, pique, terry or fleece fabric differs not only in appearance but also in structure, GSM, stretch, stability, cost and end use.

For practical textile work, the most important learning is this: fabric structure, yarn count and GSM must be studied together. A 30s yarn in single jersey, pique, rib or interlock will not give the same fabric weight or behaviour. The loop arrangement changes everything.

Therefore, whenever we select a knit fabric, we should not ask only, “What is the GSM?” We should ask:

  • What is the fibre content?
  • What is the yarn count?
  • What is the knit structure?
  • What is the stitch density?
  • What is the end use?
  • What kind of comfort, stretch and stability is required?

This is how a simple knit fabric table becomes a practical tool for garment development, costing, quality control and merchandising.

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