over dyeing on apparel

GARMENTS OVER DYEING

Prepared By:MD.AZMERI LATIF BEG

ID: 142-32-257Course Title: Apparel Wash, Dyeing & Finishing.

Course Code: AWF-514M. Sc in Textile Engineering

Department of Textile Engineering

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. Garment dyeing is the cost effectiveness of mass producing identical garments of particular colors.

In general sense garment dyeing is the process of dyeing fully fashioned garments (such as pants, shirts, pullovers, t-shirts, jeans, sweaters, dresses, bathrobes, casual jackets, skirts, hosieries) subsequent to manufacturing, as opposed to the conventional method of manufacturing garments from pre-dyed fabrics.

Technique used for Garment dyeingThere are various technique used for garment dyeing; recently some latest technology has developed for garment dyeing in our industry. 1. Tie dyeing2. Dip dyeing3. Spray dyeing

4. Over dyeing5. Cold dyeing6. High white dyeing7. Washable dyeing8. Reverse dyeing9. Top dyeing

(Over Dyeing) to dye for a second or third time with a different color. Over dyeing is such a rewarding way of rescuing an ugly or unsatisfactory colored cloth. It gives uneven look. sometimes over dyeing doesn’t mean all-time dyeing the garment which is previously dyed. Over dyeing may be normal dyeing or piece dyeing process.

Two times garments dyeing are called over dyeing.First garment is dyed by pigment dyes then again dyeing with direct dyes this is also called over dyeing.Tinting by any kinds of toner is also called over dyeing.Ready for dyeing(RFD) is dyed by any color is called over dyeing.Fabric is dyed in any color then make garment without accessories finally after making garment again dyed by same dyes is also called over dyeingReady for dyeing(RFD) is printed by suitable technique then dyed by reactive or direct or pigment dyes is called over dyeing

But in over dyeing process sometimes printed garment is dyeing, basically pigment printed. This method is the best process of the dyeing of garments. However, the penetration of the dye solution may not be completely passed to the fibers such as between the seams, buttons, zippers etc. In over dyeing process reactive, direct and pigment dyes are commonly used.

Factor consider for over dyeing of a garmentGarment accessories like zips, buttons, etc impose restrictions. The garments produced from woven fabrics create many problems and it has been found that the existing textile treatment styles as developed for piece dyed fabric cannot be just assembled for garment wet processing operation such as garment dyeing, unless they have been engineered from the original design stage for garment dyeing.The factors governing processing of ready-made garments are• Sewing Thread• Metal Components. Shrink behavior• Accessories• Foreign substances• Interlining• Care labeling.

Selection of FabricFor 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.•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 NickelPolyester buttons for pre determined colors.Nylon preferredWooden 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 and Care Labels& EmbroideriesCare 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.

Selection of Sewing ThreadCotton 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.

Selection of SewingSewing Recommendations:

Stitch densityThread TensionStitch and Seam typeNeedle size

Garments Over Dyeing Fabric Dyeing 1. When garments are made from dyed fabric and then the garments are dyed in required color and shade called garments over dyeing. It quick response to fashion change.

1. Fabric dyeing is the method after weaving, knitting or non woven to make fabric. This is a very popular method of dyeing of the dyed fabrics will be processed further to garments industries very easily.

2. Less time is required. 2. More time is required. 3. Comparatively low cost of production.

3. Comparatively higher cost of production then garments over dyeing process.

4. For direct dyeing M: L ratio maintained between 1: 10

4. For reactive dyeing M: L ratio maintained between 1: 8

6. GSM is increase after dyeing. 6. GSM is also increase after dyeing.

7. Generally Belly machine is used for garments dyeing.

7. Generally Jet/Jigger/Pad/ Winch dyeing machine are used

8. Less production than Fabric Dyeing.

8. Higher production than Garments over Dyeing.

9. Comparatively lower space is needed.

9. Comparatively higher space is needed.

10. Less possibility of shade variation.

10. It has possibility of shade variation.

11. For direct dye pH is needed 4-7. For reactive dye pH is needed 9-11.

12. Sewing thread used for making the garments should be of same fiber like the garments fabric, otherwise color difference may occur between garments fabric and sewing thread.

12. No need of sewing thread.

13. After dyed garments no need processed further to garments industries.

13. After dyed fabrics must be processed further to garments industries.

Garment Dyeing Machines for over dyeingThere are two types of equipment regularly used for garment dyeing. In our local industry Belly (cylinder drum) and front rolling(digital machine) types machine are used.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.

Over dyeing

Apparel wash, dyeing and Finishing

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

GARMENT DYEING MACHINES

Over dyeing

M. Sc in Textile Engineering

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


Over dyeing


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


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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

GARMENT DYEING

MACHINES

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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． Thermomete

r6． Indirect

heating valve7． Direct

heating valve8． Trough body

water supply valve

9． Trough body drainage valve

10.Cooling drainage valve

11.Drainage controller


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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


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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


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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


Over dyeing


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


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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.


Over dyeing


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


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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.


Over dyeing


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.


Over dyeing process for a dyed garment For over dyeing of a dyed garment select the dye which is previously used for dyeing the fabric that form the garment. In the below I shown a standard recipe and flow chart which is previously dyed with reactive dye during fabric form. Now over dyeing is done by reactive dyes. It gives uneven look. When buyer said it will over dyeing we try to dyeing light during fabric dyeing. We may use extra toner to give effective tone. In market different types of toner is available.

Over dyeing of a garment with reactive dyesDyeing recipe: (for a standard shade)Reactive black dyes = 0.8 %Reactive red dyes = 1.0 %Reactive yellow dyes = 0.05 %Salt = 30 g/lSoda = 10 g/l

Over dyeing of a garment with direct dyes on dyed garmentDyeing recipe: (for a standard shade)Direct black dyes = 0.7 %Direct red dyes = 1.0 %Direct yellow dyes = 0.06 %Salt = 30 g/l

Over dyeing of a garment with pigment dyes on dyed garmentDyeing recipe: (for a standard shade)Pigment black dyes = 0.9 %Pigment red dyes = 1.6 %Pigment yellow dyes = 0.08 %Binder=1-1.5 g/lCatanizer=2-2.5 gm/l

*Pigment dyes is not suitable for deep shade because dyeing cost is not meet, so when deep shade is required garment is tint by direct dyes.

ConclusionHowever, the over dyeing is not coming without any strings attached to it; the cautions are often pronounced in terms of fabrics and their preparation, accessories used in the garments for safe operation. By over dyeing get some extra benefit that is look and feel of garment over dyed clothing is better than fabric dyeing garment. Garment over dyeing has changed the industry by allowing retailers and distributors to respond quickly to the rapid changes in color, styles and finishes demanded by today's market.

Reference:•http://www.slideshare.net/prabukrishnaa/garment-dyeing-techniques?qid=ea2993db-0989-4751-9417-00bff5cc322d&v=qf1&b=&from_search=1

•http://www.slideshare.net/sheshir/garments-dying-machine•http://www.dyehouseltd.com/garmentdye.html

•http://www.coatsindustrial.com/en/information-hub/apparel-expertise/sewing-post-dyed-garments

•Md. Mahamudul Hasan(Wash Technician) of Ayesha Washing Ltd.(A Sister Concern of Palmal Group) in Jamgora, Ashulia, Savar,Dhaka., Cell: +8801747284925, +8801672130171, Email: [email protected], [email protected]

•Md Sohel Rana(Wash technician) of Hamim Washing in Nisadnagor, Tongi, Dhaka. Cell: +8801736571160

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AZMIR