garment dyeing techniques

KCT, Dept.of Fashion Tech

Apparel Finish and Care

Dept. of Fashion Technology, KCT, Coimbatore.

UNIT – IGARMENT DYEING

GARMENT DYEING

FABRIC SELECTION

SEWING THREAD SELECTION

ACCESSORIES SELECTION

DYE SELECTION

GARMENT DYEING MACHINERY




GARMENT DYEING

What is garment dyeing?

Garment dyeing is the process of dyeing fully fashioned garments. (such as pants, pullovers, t-shirts, jeans, sweaters, dresses, bathrobes, casual jackets, shirts, skirts, hosieries)

As opposed to the conventional method of manufacturing garments from pre-dyed fabrics.

Most garments are made of cotton knit goods and/or cotton woven fabrics.

Although several other fabrics can be found in the whole or in part such as wool, nylon, silk, acrylic, polyester and others.

Due to cost savings and fashion trends, garment dyeing has been gaining importance and popularity in the past years and will continue to do so in the future.




Need of garment dyeing

Traditionally, garments are constructed from fabrics that are pre dyed (piece dyed) before the actual cutting and sewing.

The advantage of this process is the cost effectiveness of mass producing identical garments of particular colors.

Quick Response to the market (bar coding etc.,) Ability to supply a wide range of colorations to the retailer, but

only in the shades that are selling Reduced discounted sales at inventory Best way to achieved relaxed, casual look Ability to create special effects such as tie dyed, pigment dyed

and washed down in a single process etc.,

GARMENT DYEING

A major drawback with this approach is the risk associated with carrying a large inventory of a particular style or color in today's dynamic market.


Special considerations to garment dyer

- Very good communications between all parties involved- Preparation - may be done on piece goods or on garments clean

substrate for dyeing reduced shrinkage (preferably squared) for wovens should be less than 5% for knits should be less than 8%

- Metal components should be non-ferrous pewter buttons are acceptable

- Non-metal components that are not sensitive to dye chemistry or temperatures at a boil are acceptable

- polyester zippers, buttons, etc. which are clear or predyed tie dyed splatter dyed

- weathered pigment dye and wash down in a single process nickel plated brass zippers are acceptable

- Velcro - clear or predyed- special polyamide buttons which are dyeable- Threads must be of same fiber as the fabric in the garment or

"grinning" will occur.- Pre dyed threads may be used- Corespun threads with a strength or stretch yam in the core and the

desired fiber on the outside- Covered threads may be used- "Tacking" of sleeves and pant legs to prevent tangling






GARMENT DYEING

• The dyeing of the garments requires more care than the dyeing of the fabric, though there is very little difference in the dyeing procedures. This is due to the fact that processing of garments involves value added goods.

• The entire garment dyeing activities may be broken down in to four categories:

1. Fully fashioned garment dyeing carried out by major dyers and finishers

2. Cut and sewn garment covering woven and knitted fabrics.

1. Dyeing of 100% cotton goods for boutique trade suitable for hand washing. and

1. Washing, desizing, bleaching denim goods, leading to stone wash, snow wash, over dyeing and highlighting effects.

Categories of Garment Dyeing




GARMENT DYEING

Advantages of Garment Dyeing

Flexibility towards fast changing market trends

Quick response and rapid turnaround

Flexibility towards dye shades and finishes

Flexibility of lot size

Flexibility of items to be dyed

Comparatively less rejection

Low inventory

Less capital investments

Fancy effects

Disadvantages of Garment Dyeing

Labour intensive process and requires thorough checking of every piece

Higher “seconds” rate

Poor appearance

Poor reproducibility of shades

Special care in the selection of fittings

More material handling




SELECTION OF FABRIC

Lots or batches of greige fabric must be selected that will dye up identical in shade.

Loom state fabric must be converted into RFD (ready for Dyeing) Stage.

- Desized, Scoured for dark colours,- Desized, Scoured and bleached for light colours

To get the best-looking garments.

- Desized, Scoured, bleached and Mercerized

For heavily swelling fibres such as cotton, the elasticized areas, waist bands and cuffs, must be fairly slack, and seams should not be too tight or bulky.




SELECTION OF FABRIC

Shrinking behavior of the fabric must be uniform before garment dyeing.

Articles which are prone to Crease marks or Pilling effects should be turned inside out and dyed with the addition of a non-foaming lubricant while adopting the shortest possible dyeing process.

Fabrics should be free from foreign materials (Contamination)

The interlinings used are to be checked for their performance to satisfy the requirement.

- Dyes to be taken as same as the outer fabric.- The gum should not be removed off from the surface- The resin in the interlinings should not make adverse

effect on the dyeing color.




SELECTION OF ACCESSORIES

Buttons, Studs and Zippers: Free from Nickel Polyester buttons for pre determined colors. Nylon preferred Wooden to be verified before usage. Brass, antiq brass, silver, gun metal, golden zippers can be used

and to be checked before the bulk process. Studs and Buttons may be used after dyeing of the garment most

of the cases to avoid breakages and damages to the fabric.

Care Labels& Embroideries Care labels to be used are to be good in fastness properties. It should not absorb the dyes from the bath. Polyester care labels are mostly used. A pouch may be used to avoid dye penetration on the care labels. Embroidery threads are used as polyester threads for pre

confirmed colors. If the effect is required, then RFD cotton yarn is used for the

embroidery as like sewing threads.




SELECTION OF SEWING THREAD

Cotton thread is preferred in most of the garment dyeing. They should be of same lot. Polyester threads can be used only in pre determined

colors. Nylon threads can be used. Proper care should be taken in

maintaining consistency. Sewing threads to be of high strength to withstand the

required seam strength. Mostly heavy threads than normal polyester threads are

used. Should be free from hairiness. Threads with low tension to be applied while sewing to

balance the shrinkage of threads. Depending upon the requirement, the thread numbers can

be used. Core spun yarn also be used for better performance of

seams.




SELECTION OF SEWING

Sewing Recommendations:

Stitch density Thread Tension Stitch and Seam type Needle size




GARMENT DYEING MACHINES

Garment dyeing machines

There are two types of equipment regularly used for garment dyeing.

1. Paddle machines

A high liquor ratio is required for paddle machines, which is less economical and may limit shade reproducibility.

2. Rotary drums

Rotary drum machines are sometimes preferred for garments, which require gentler handling, such as sweaters.

Many machinery companies have developed sophisticated rotary dyeing machines, which incorporate state-of-the-art technology.




1. Paddle machines:

A. Horizontal Paddle MachineB. Lateral / oval paddle C. HT Paddle Machines

2. Rotary drums

A. Rotary Drum Dyeing Machine B. Tumbler Dyeing Machine

3. Toroid Dyeing Machine

4. Modified Pegg Toroid Whiteley garment dyeing machine

5. The Gyrobox

6. The MCS Readymade garment dyeing machine

7. Leemetals epicyclic Paddle dyeing machine

Types of Machines





Working Principle:

A process of dyeing textiles in a machine that gently move

the goods using paddles similar to a paddle wheel on a boat.

This is a slow process, but there is extremely little abrasion on the goods.

1. PADDLE DYEING MACHINE





1A. Horizontal Paddle Machines

(over head paddle machine) consist of a curved beck like lower suction to contain the materials and the dye liquor.

The goods are moved by a rotating paddle, which extends across the width of the machine.

Half immersed paddles cause the material to move upwards and downwards through out the liquor.

The temperature can be raised to 98o C in such system.

Drain

Paddle Wheel





1B. Lateral / oval paddle

This machines consist of oval tank to enhance the fluid flow and the processing the goods.

In the middle of this tank is a closed oval island.

The paddle moves in a lateral direction and is not half submerged in the liquor.

The temperature can be increased up to 98o C.

Circulation

Island

Peddle

Dye Bath





1C. HT Paddle Machines

It works according to the principle of horizontal paddle machine.

however, the temperature can be raised up to 140o C.

PES articles are preferably dyed on HT paddles.

1 ． Trough body2 ． Slurry disk3 ． Door4 ． Charging

bucket5 ． Thermometer6 ． Indirect heating

valve7 ． Direct heating

valve8 ． Trough body

water supply valve

9 ． Trough body drainage valve

10. Cooling drainage valve

11. Drainage controller





In paddle machines,

The dyeing can be carried out with 30:1 to 40:1 Liquor to Material Ratio.

Lower ratios reduces optimum movement of the goods, lead to unleveled dyeing, crease formation.

For gentleness, the blades of the paddle are either curved or have rounded edges.

The rotating speed of the paddle can be regulated from 1.5 to 40 rpm.

Circulation of the liquor should be strong enough to prevent goods from sinking to the bottom.

Paddle machines are suitable for dyeing articles of all substrates in all forms of make ups.

The goods are normally dyed using PP/PET bags.

General Parameters & Features





2A. Rotary Drum Dyeing Machine

“Movement of textile material and a stationary liquor”.

The rotary drum dyeing machine consists of rotating perforated cylindrical drum , which rotates slowly inside a vessel of slightly bigger in size.

The internal drum is divided into compartments to ensure rotation of goods with the drum rotation.

The outer vessel holds the required quantity of dye liquor.

High temperature drum machines are capable of processing the garments up to 140o C.

Door

Steam Pipe


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Features of modern rotary-dyeing Machine

1. Lower liquor ratio

2. Gentle movement of goods and liquor (minimizes surface abrasion)

3. Rapid heating and cooling

4. Centrifugal extraction

5. Variable drum speed with reversal capability (adaptable to a wide variety of goods)

6. Continuous circulation of goods (improves migration control)

7. Ease of sampling

8. Variable water levels with overflow rinsing capabilities

9. Large diameter feed and discharge lines (minimizes filling and draining time)

10. Microprocessor controls

11. Lint filters

12. Pressure dyeing

13. Auto-balancing drums





One feature that can be used to reduce abrasion on delicate garments or to minimize tangling is a compartmental chamber, sometimes referred to as a "Y" pocket.

The rotary drum machines are very simple to operate and are quite compact in size.

The cost of unit is also not high .

Drum dyeing-centrifuging machines are also called

- “multipurpose drum machines” or - “multi-rapid dyeing centrifuging machines”

since these machines can perform scouring, dyeing, centrifuging and conditioning successively with automated controls.

General Parameters & Features of Rotary Machine





The goods are treated in a perforated inner drum housed within an outer drum (dyeing tank).

Inner drums without dividing walls are provided with ribs that carry the goods along for a certain time, partially lifting them up out of the liquor.

These machines can operate at very low liquor ratios and can dye the goods up to 98 -140o C.

This is suitable for knits as well as other garments.

Liquor circulation can be intensified using additional jets.

Drums can be rotated in both the directions.

Working Features of Rotary Machine





2B. Tumbler Dyeing Machine

These machines are being used for small garments either in loose form or in open mesh bags.

Design wise the tumbler dyeing machines are similar to the commercial laundering machines.

The principle of operation is to load the material into perforated inner SS tanks , which rotates round a horizontal shaft fixed at the back of the drum.

The drum is divided into compartments for moving the goods with rotation of drum.





A variety of tumbling machines have higher rotation speeds and can spin dry at the end of the cycle.

These are similar to dry-cleaning machines.Rotating drum machines are more efficient and cleaner to operate than paddle machines.

The more vigorous mechanical action often promotes more

shrinkage and bulking, which may be desirable for some articles.

In order to handle higher quantities and large production of similar pieces the latest machines are provided with several automatic features and sophistications.

General Parameters & Features of Tumbler Dyeing Machine





3. Toroid Dyeing Machine In these machines the garments

circulate in the liquor in a toroidal path with the aid of an impeller situated below the perforated false bottom of the vessel.

Movement of the goods depends completely on the pumped action of the liquor.

High-temperature versions of this machine operating at 120 to 130°C were developed in the 1970s for dyeing fully-fashioned polyester or triacetate garments.

The liquor ratio of such machines is about 30:1.


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4. Modified Pegg Toroid Whiteley garment dyeing machine

This is an improved version of Toroid machines , the additional features are:

The machine is suitable for both atmospheric and pressure dyeing.

Full automation upto hydroextraction.

The design features, speed and performance is simplified to make the machine more versatile and free from operating problems.





5.The Gyrobox

The machine has support in the form of a large wheel, which is divided into 12 independent non radial compartments.

The goods are placed in these compartments .

The wheel runs at a moderate speed of 2-6 rpm.

The main advantage of this machine are,

1.Reduced M:L

2.Different types of garments can be dyed simulteneously .

3.Flexible loading

4.Fully automatic operation.





6. The MCS Readymade garment dyeing machine

The rotodye machines are suitable for dyeing pure cotton, wool, polyester, cotton blends in the form of T shirts, sweaters, bath rugs and accessories , socks and stockings.

7. Leemetals epicyclic Paddle dyeing machine.


garment dyeing techniques

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