Dying Printing Finishing 100504132149 Phpapp01

8/3/2019 Dying Printing Finishing 100504132149 Phpapp01

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Dyeing, Printing

and Finishing

For the benefit of business and people

March 2006

Srini VenkataramanDr. Sandeep Khatua

Bureau Veritas

Consumer Products Services

VESTEX


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2

1) Preparatory Process and

Their Importance2) Dyeing

3) Dyeing Techniques

4) Printing

5) Dyeing / Printing Problemsand Remedies

6) Finishing

Summary


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3

Preparatory Processand Their Important

1


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4Bureau Veritas Consumer Products Services

8 Remove impurities (both natural and/or those addedduring production) from the fibers.

8 Improve the ability of the fibers to absorb water solutions of dyes and chemicals.

8 Impart the proper brightness or whiteness to fibers

according to need, especially when brilliant or certain pastel shades are desired, and

8 Impart dimensional stability to thermoplastic textile

materials.

1 Preparation Objectives


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8 The importance of adequate and uniform preparationprior to dyeing cannot be overemphasized. Improper removal of impurities can lead to unlevel dyeing,streakiness, and poor penetration.

8 It is estimated that more than 60% of faulty dyeingare the result of improper preparation.

8 Preparation procedures may vary greatly from onefiber type to another. While natural fiber usuallyrequire extensive scouring and bleaching, syntheticfibers may need only a mild scouring.

ImportancePreparation1


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Preparation

8 Important Preparatory Steps for Cotton Fabric

Singeing

Desizing

Scouring

Bleaching

Mercerizing

1



8 Removes superficial hairiness from yarns, lint, looseyarns, and surface dirt from the face of the fabric andtherefore provides more even surface for dyeing.

8 It also reduces formation of pills, or balls of fiber, onthe fabric.

8 After the surface of the fabric is raised by brushing,

the protruding fiber ends are burned off by thesingeing process. In this process the fabric is passedthrough the small gas flame.

8 Note: Consumers may detect increased pilling inimproperly singed Cotton fabrics. When Cottonblends are singed, care must be taken to avoidoverheating the thermoplastic fibers.

Preparation1 Singeing



8 Prior to weaving, Cotton warp yarns are coated withsizing materials to provide them with additionalstrength, and resistance to abrasion. The mostcommon sizing materials used are different kinds of starches, and various grades of partially hydrolyzedpolyvinyl alcohol.

8 Enzymes are often used for the effective removal of starches.

8 The main advantage of enzyme desizing is that thereis no risk of damaging the fibers. However, enzymaticdesizing is relatively expensive since it can not becombined with other preparatory operations.

Preparation1 Desizing



8 This cleaning treatment, often referred to as alkali boil-off, removes most of the Cottons impurities, whichincludes natural and other impurities as well as sizingresidues that were not removed during desizing.

8 In scouring the fabric is treated with a strong alkalisolutions, close to or above the boil, for 1-2hours. Ahot rinse is needed to remove the emulsifiedimpurities. The final rinse may include a small amountof acetic acid if the fabric has to be neutralized.

8 Manmade fibers, especially those that have beenheavily treated with spinning oils, are occasionallyscoured with solvents.

Preparation1 Scouring



8 The purpose of Bleaching is to provide a uniform whitesurface on a fabric. It is chemical oxidation thatdestroys the colored impurities present.

8 Control of whiteness of bleached fabric is important towet processing that follow.

8 Hydrogen Peroxide is the chemical most commonlyused today for bleaching Cotton compared to SodiumChlorite

8 Open Width Method and Rope Method : Open widthmethod is widely used method especially whenbleaching blends of Cotton with heat-sensitive fibers inorder to avoid crease marks and other defects caused

by treating fabrics in the rope form.

Preparation1 Bleaching



Open Width Method




Rope Method




8 Two Types:1) Tension Mercerization

The purpose of mercerization is to increase luster of Cotton fibers

The fiber untwists and swells, lumen becomes rounder incross-section and it gains luster. Dye affinity and chemicalreactivity increase. Fabric becomes stronger andsmoother.

2) Slack Mercerization

Not as lustrous as tension method Elongation and recovery properties improve and thus have

been used to produce comfort stretch garments and fabricbandages, which need to conform to body shapes.

Preparation1 Mercerization



Preparation Mercerization

Note: Fabric Mercerizationis Cheaper than doubleMercerization whichprovides a softer hand

1



8 Knitted fabrics are pre-relaxed to minimizetorque, puckering of seams, and shrinkage during

dyeing and drying. Conveyor type relaxationdryers and / or compacting are used to minimizeresidual fabric shrinkage.

8

After knitting, the lubricants (added to improveknitability) must be removed with a water-basedor solvent scouring process.

Preparation1 Knit Fabric


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8 Heat-setting or thermosetting is a heat treatment appliedto fabrics made of thermoplastic fibers such as polyester or Nylon to impart dimensional stability.

8 Heat-setting affects the dye-ability of the fiber. Usually itdecreases its dye-ability, and therefore when performedbefore dyeing it is extremely important to apply the heat-

setting uniformly.8 Uneven temperatures in the oven may cause differences in

the fabric from selvage to selvage and/or from selvage tocenter which will show later as unlevel dyeing.

Preparation1 Thermoplastic Fabrics


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Dyeing

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8 Dyeing is by far the most widely used means of applying color to textiles.

8 Dyes, by definition, are soluble in the mediumin which they are applied, and the medium isalmost always water.

Dyeing2


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8 There are several different ways by which coloringmaterials are classified.

8 Classification of dyes by the method of application is

the most common one, which are: Acid dyes (Protein fibers, polyamides etc)

Basic dyes (Acrylics, Basic dye-able polyester, etc)

Direct dyes (Cellulosics, and some others)

Azoic dyes (Cellulosics)

Vat dyes (Cellulosics)

Reactive Dyes (Cellulosics)

Disperse Dyes (Polyester, Acetate, Polyamides, acrylics,and Other Hydrophobic fibers)

Dyeing2 Classification and Fibers


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Immerse Textile in Dye-bath

Apply Heat, Time, Chemicalsto Drive Dye into Textiles

Rinse to Remove Surface Dye

All Dye is in Bath

Most of the DyeNow on Textiles

Unfixed SurfaceDye Removed

Fabric

Dyeing

Fabric

2 How Dyeing Takes Place


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Polymer Morphology Inside a Fiber

Dyeing2 How Dyeing Takes Place


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Typical Reactive Dyeing Process on Cotton Woven

Dyeing2


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8 The Major System Variables

Textile substrate

Application method

Dye selection and formulation8 Need to Control These Variables in Order to Achieve:

Target shade predictability

Required fastness

Efficiency in terms of cost of materials and plantoccupancy

Dyeing2


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8 General Principles and Terms Met in Dyeing1) Dye Exhaustion This describes how much of the total

dye applied resides on the fiber rather than in the dye

liquor 2) Equilibrium This is when the final or equilibrium

degree of exhaustion has been reached. If the dyeing isallowed to proceed under the same conditions for a

longer time, the shade of the dyed goods will remain thesame.

3) Levelness and Leveling Power - levelness depends on: Liquor ratio The leveling power increase as the LR

increases as there is more dye in the bath Substantivity Low substantivity favors leveling

Temperature Higher temperature give more level dyeing

Time Longer times give more level dyeing

Dyeing2


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8 Dyeing Can Be Done at Different Stages:

Fiber Stage

Yarn Stage

Fabric Stage

Garment Stage

Dyeing Stages2


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Dyeing Stages2


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8 Stock Dyeing

Masses of loose fibersare placed in large drumsinto which dye is pumpedand circulated.

Tweed fabrics with aheather-like color effectsuch as Harris tweed isdone using this method.

Dyeing Fiber 2


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8 Producer or Solution Dyeing

Colorant is added to thespinning solution before thepolymer mix is extruded andformed into a manufacturedfiber.

This method is very desirablewhen high colorfastness isdesired such as automotive

seating fabrics, carpeting etc.

Dyeing Fiber 2


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8 Yarn Dyeing

Yarns are immersed into adyebath prior to being made intofabric.

Loosely wound hanks can bedyed (skein dyeing) ,

Yarns wound into small tubescalled package can be dyed(package dyeing) , or

The entire warp beam can beimmersed into dyebath (beamdyeing) .

Dyeing Yarn2


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8 Beam Dyeing

Both yarn and fabric can be dyed by this process

Dyeing Yarn / Fabric Dyeing2


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8 Piece Winch (or beck) Dyeing

Fabric pieces are sewn end to

end and this rope-like form isdyed in a relaxed state.

It is most widely used onknitted, woolen and worstedfabrics.

Dyeing Fabric2


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8 Piece Jet Dyeing

Dyeing is done in a

closed, tube-likesystem in which thefabric passes througha fast moving stream

of pressurized dyeliquor.

It is primarily used for fabrics prone tofelting .

Dyeing Fabric2


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8 Piece Jig Dyeing

Fabric is treated in openwidth and is passedthrough the dye bathrather than immersed in toa dye bath and this isrepeated.

There is a degree of tension on the fabric and

is therefore used onwoven fabrics and notknits.

Dyeing Fabric2


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8 Piece Pad Dyeing The dye solution is applied

by means of a padder andthe fabric in open form isrun through an open vat.

The fabric is subject to

tension, so only selectedfabrics can be dyed.

Advantages: System canhandle thousands of yards

and dye can be addedautomatically to provideconsistency of dye color

Dyeing Fabric2


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Dyeing is done oncompleted garments.

Garments are placed ina nylon bag and placedin large tubs containingdye bath.

Garments havingdifferential shrinkageamong variouscomponents may have

difficulty being dyed bythis method.

Dyeing Garment2


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Dyeing Techniques

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8 Reactive Dyeing The reactive dyes are water-soluble anionic dyes, which

react with hydroxyl groups of cellulose to becomecovalently bonded to the fiber

The chemical reaction between a reactive dye and acellulose fiber takes place in the presence of a base and

can be summarized as follows

Offers bright colors with very good colorfastness,(particularly good washfastness and excellent lightfastness).

Susceptible to damage from chlorine bleaches

ReactiveDyeing Techniques3


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8 The Vat dyes are insoluble organic compoundsthat are not substantive to cellulose.The following steps are involved in dyeing:1) Reduction (Vatting): Prior to dyeing they are converted

to their soluble form (leuco soluble vat dye) by means of reduction in the presence of a strong base.

2) Dyeing: In this soluble form, they are substantive tocellulosic fibers, and can be applied to them.

3) Oxidation: Once inside the fibers, uniformly distributed,

the Vat dyes are then oxidized and converted back totheir original insoluble form.

4) Soaping: to achieve a stable shade.

VATDyeing Techniques3


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8 The soft water throughout the dyeing stage is amust with Vat dyes, since the soluble Leucosalts form insoluble salts with Calcium or Magnesium ions as well as with transitionmetals.

8 A wide choice of colors with good to excellentcolorfastness is available, although their lightfastness may be somewhat inferior.

VATDyeing Techniques3


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8 Sulfur dyes are insoluble in water and their applicationto cellulosic fibers resembles that of the Vat dyes inprinciple. They are relatively low in cost.

8 Traditionally they were used for dark shades (browns,blacks and navy blues) but some of the newer dyes areavailable in bright colors .

8 Sulphur dyes (if applied incorrectly) on material stored at

higher than normal room temperature and in presence of moisture tend to oxidize to form strong sulfuric acids.These acids will then cause tendering of cellulose fibers.To prevent tendering, the final rinse is carried out withmild alkali solutions.

8 Sulfur dyed fabrics have good colorfastness to washingbut are sensitive to chlorine bleaching. Lightfastness isonly fair but is adequate for most end uses not requiringprolonged sunlight exposure.

Sulfur Dyeing Techniques3


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8 Direct dyes are soluble anionic dyes.8 The Direct dyes are so called because they were the first

dyes to dye cellulosic fibers directly without the need for a

pre-treatment of the fibers with a mordant.8 The mechanisms by which direct dyes become attached to

cellulose is assumed to be through the formation of a largenumber of weak attractions between the dye and the fiber.

8 Direct dyes exhibit relatively good colorfastness tosunlight, and some are considered to have excellentlightfastness. However colorfastness to washing is poor

and therefore not appropriate for frequently washedapparel.

8 The problem of poor washfastness can be improved to

some degree by formaldehyde after treatment.

DirectDyeing Techniques3


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8 The disperse dyes are non-ionic aromatic compoundswith an extremely low solubility in water.

8 Disperse dyes require special fabric preparation for

uniform application . Dyeing procedure for Polyester fiber include ;

1) Low temperature dyeing with dye-carrier

2) High Temperature/High Pressure Dyeing3) Continuous dyeing by the thermosol process

8 Extremely colorfast to laundering. Good colorfastness to

light and dry cleaning. But dyes may sublime( evaporates)when exposed to high temperature in pressing.8 Fume fading is a problem with disperse dyes. It is not

unusual to see acetate linings turn pink after storage in anarea with gas heat.

DisperseDyeing Techniques3


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Dyeing Techniques3


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Dyestuff Properties

Dyeing Techniques3

Good

Good

Fair Good

Fair Good

Fair Good

Wet Poor Dry Good

Fair Good

Good

Crockfastness

GoodGood ExcellentGood

ExcellentFairly DifficultAverage

+Vat

GoodFair GoodGoodFairly DifficultCheapSulfur

Fair GoodGoodGood

Excellent

(if soaped)

Average Fairly Difficult

Average

+Reactive

Fair GoodGoodGoodHardAverageNaphthol

Fair GoodGoodGoodFairly HardAverageDisperse

Poor GoodFair GoodPoor GoodEasyCheapDirect

Fair GoodPoor GoodPoor GoodAverage Fairly DifficultAverage

+Basic

GoodGoodFair - GoodAverageAverage

-Acid

Perspiration

FastnessLightfastnessWashfastnessEase of ApplicationCostDyes


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8 Union Dyeing In union dyeing, the components of a blend are dyed

with the same shade to obtain a solid color.

Dyes must be carefully selected and properly appliedto ensure color uniformity.

Union dyeing can be applied by two methods: One-bath (single dye) and Two-bath (double dye) methods.

Polyester/Cotton intimate blends are often dyed withthese methods.

Two-bath method offers better result onPolyester/Cotton blends compared to One-bathmethod.

One-bath method is cheaper than Two-bath method.

BlendsDyeing Techniques3


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8 Cross Dyeing

The method of obtaining a multi-color effect on a blend

is referred to as Cross-Dyeing. In cross dyeing, a fabric containing two or more fiber

types or fiber variants is purposely dyed so that eachfiber type or variant accepts a different type of dye andbecomes a different color.

The end product depends on the fiber arrangement inthe fabric. It may be a check, a plaid, a tweed, a stripe, a

muted color, a heather effect, or some other design.

BlendsDyeing Techniques3


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8 Advantages Pigment coloration is economical because of limited

number of processing steps.

Blends can be dyed a uniform shade with one operationapplicable to all fibers.

Pigment coloration has an extensive color range and

high light fastness. Pigment coloration has satisfactory washfastness.

8 The possibility of combining dyeing and finishing

exists with pigment coloration. Products must beselected so that finish and binder react under same conditions of pH and/or temperature.

Pigment ColorationDyeing Techniques3


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8 Disadvantages

Heavy shades crock badly. Light shades may wet crock.

Pigment coloration is normally applied by padding.

Pigment adversely affects hand. The large amount of binder required may stiffen fabric. This is most noticeable on very

thin fabrics. Pigment coloration may have sticking or buildup on pad

rolls.

Migration (uneven coloration) may occur if drying is variableor pickup is high.

Dyeing Techniques3 Pigment Coloration

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8 Optical brighteners, also called FluorescentBrighteners or Fluorescent Brightening Agents (FBA)are colorless dyes that work by emitting visible lightwhen exposed to invisible ultra-violet light.

8 They are used to make white or light-colored fabricsappear brighter. Mostly bleached white fabrics aretreated with these brighteners.

8 Fabrics and garments that are truly prepared for dyeing should not contain brighteners. Opticalbrighteners can interfere with some dyes bycompeting for the "dye sites" on the fibers.

Optical BrightenersDyeing Techniques3


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Printing

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8 The application of colorant in definite, repeatedpatterns to fabric, yarn or sliver.

8 The different methods of printing include handscreen, automatic screen, rotary screen, roller and heat transfer.

8 Each method can be used to print one or moreprint types.

8 These include direct, discharge and resist prints.

Printing4

4


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8 There are Three Methods of Printing:

Screen Printing

Roller Printing

Heat-Transfer Printing

Printing4

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8 Screen Printing

This printing involves coating of a screen fabric (madeof nylon, polyester, or metal tightly mounted on awooden or metal frame) with an opaque nonporous filmwith the design areas cut out of it.

The screen is placed on top of the fabric, print paste is

poured into the frame and forced through the mesh. The dye can then pass through the fine mesh and coat

the fabric only in the areas of the design.

Each color requires its own screen and separateapplication of color. Also each color of the designmust be precisely located on the screen so that itbecomes properly placed and printed.

Printing Methods4

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8 Screen Printing

Types of Screen Printing Include:

Flatbed Screen - Hand or Automatic

Rotary Screen

Printing Methods4

4


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8 They are used primarily to print on flatsubstrates

8 Consists of a bed or vacuum table thatholds the substrate in place duringprinting, a carriage that holds theprinting screen, and a squeegee.

8 Printing takes place in three steps.

First, ink is poured on the screen, andthe screen is moved into position over the substrate. Then the squeegee ispressed against the mesh and drawnover the image area to push ink through

the open areas of the screen onto thesubstrate. Finally, the screen is liftedaway from the substrate.

Printing Flatbed Screen4

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Rotary Screen Printing Process

Printing4

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8 The equipment costs for Flatbed screen printing arelower than other printing processes, but the rate of production is usually slower.

8 Rotary printing is a continuous, stepless imagetransfer method whereas flatbed printing is a twostep process.

8 Flatbed screen printing is good for small repeatunits or rigid stock printing (impossible to supporton rotary machine).

8 Rotary screen is best choice for coarse halftonesand specialty inks.

Printing Rotary vs Flatbed Screen4

h d4


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8 Roller Printing

In this printing method, the design is put onto fabric

by copper engraved rollers or cylinders. A separate engraved roller is required for each color.

Copper rollers can be engraved with very fine

delicate designs. The size of engraved cylinders is governed by the

printing machine and the design.

Printing Methods4

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Printing Roller Printing Process4

P i I k4


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8 Two Types of Ink are Used in the Textile Industry:

1) Water-based Ink

2) Plastisol Ink

Plastisol is the choice for printing of finished goodssuch as T-shirts, sweatshirts, jackets, and tote bags.

Water-based ink is the ink of choice for the printingof yard goods; either in piece form or on the roll.

Printing Print Inks4

P i i Pl i l P i i4


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8 Plastisol ink is a PVC based system that contains nosolvent.

8 It is thermoplastic that requires specific heat and time for

complete curing. Failure to follow proper curing guidelineswill result in an under Cure of the print and therefore willcause poor washfastness, and/or a resistance to abrasion.

8 The performance of plastisol can be affected by additionof additives such as Extenders, plasticizers, reducers andresins.

8 Problems such as fading, pulling away and/or crackingcan occur if additives are used properly.

8 If not cured properly, phthalates (a commonly usedplasticizer) could cause skin irritation.

Printing Plastisol Printing4

P i i Pl i l I k4


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8 Advantages of Plastisol Inks

User-friendly, very easy to manage

Can be left in the screen for extended periods of timewithout clogging the mesh

It is ready to use right out of the container more than

90% of the time

Can be printed wet-on-wet, which allows for increasedproduction speeds

Can be printed on light and dark fabrics

Disposal of waste plastisol is a simple process

Printing Plastisol Inks4

P i i W t b d Li k4


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8 Advantages of Water-based Inks

Good choice when soft hand is desirable

Excellent for high speed roll-to-roll yardage printing

Such printing is done on large sophisticated equipmentthat has very large drying (curing) capacity.

Good choice where ink penetration is desirable such asin towel printing

Printing Water-based Links4

P i ti Pl ti l W t b d Li k4


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Fair Low -ModerateSoftLow -

MediumEasyHardWater-based

ExcellentModerate -

HighMedium -

HeavyLow-HighFair EasyPlastisol

WasteInk

RecoveryCostHandOpacity

Easeof

PrintingCuring

ExcellentPoor Yardage

ExcellentPoor Towels

Fair GoodNylon Jackets

Poor GoodT-shirts, dark colored

ExcellentExcellentT-shirts, light colored

Water-basedPlastisol

Printing Plastisol vs. Water-based Links4

P i ti M t lli P i t4


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8 Metallic inks are simply finely ground metal and/or plastic flakes that are suspended in a clear plastisolbase.

8 can be used as accents in a design or as the entireprint.

8 One of the biggest problems with metallics is that

some brands that use metal flakes dull and tarnishbadly after the first washing but small plastic flakethat doesn't tarnish

8 A popular technique to improve the washability andbrightness of metallic prints is to add 5% nylon

jacket bonding agent to the mixture. This helps sealthe metal particles and minimize the tarnishing.

Printing Metallic Prints4

P i ti g Glitter4


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8

Glitter ink is made up of small mylar flakes that aresuspended in a clear plastisol base.8 Comes in wide variety of colors ranging from your basic

silver and gold, to more vivid green, purple, cherry and

more.8 Because of the size of the glitter particle, this ink is not

designed for detailed prints. It works best as a highlight inkfor a design that need a little glitz. It works well on both lightand dark shirts because the glitter flake makes the ink veryopaque.

8 The clear base of the glitter mixture will need to be cured just like a normal plastisol except the ink deposit is so thickthat a longer tunnel time is very important.

8 Glitter washes very good and will flake just a little. Unlikemetallic ink that will dull, glitter retains it's brilliancebecause the flake is mylar and does not tarnish like somemetallics.

Printing Glitter 4

Printing Methods4


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8 Heat-Transfer Printing This is also called thermal transfer printing.

In this method the design is first printed on

paper with printing inks containingdisperse dyes.

The printed paper (called transfer paper) isplaced on the fabric and passed through

heat-transfer printing machine at about400F. Under this temperature, the dye onthe paper sublimates and is transferredonto the fabric.

Disperse dyes is the only class of dyes thatcan be sublimated and used for thismethod of printing.

Printing Methods4

Printing4


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8 Heat transfer is ideal for printing small runs of many products, especially where full color is

required.8 Heat transfer minimizes the need for large

inventories of printed garments.8 Adaptable when it comes to garments that are

difficult to print, such as those with buttons andzippers.

8 Heat transfers allow a halftone print to be moire-free and have minimum fibrillation.

Printing4

Printing Types4


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8 There are Different Types of Prints Including:

Direct or Application Print

Discharge Print

Resist Print

Blotch Print

Warp Print Flock Print

Burn-out Print

Duplex Print Pigment Print

Engineered Print

Printing Types4

Printing Types4


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8 Direct Print

Also called applicationprint. Design is printeddirectly onto a white

cloth or a previouslydyed fabric. They arethe most popular printtypes.

Printing Types4

Printing Types4


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8

Discharge Print Fabrics are dyed a solid color prior to printing. When printing is

done, the design is applied by screen or roller with a chemical whichremoves the color of the originally dyed fabric. Discharge prints can

be made with rollers and screen methods. They are not widely usedbecause production costs are high.

Printing Types4

Printing Types4


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8 Resist Print It involves a two step procedure: (1) printing a pattern design

on a white fabric with a chemical that will prevent penetrationof dyes; and (2) piece dyeing the fabric. The result is a dyed

background with a white patterned area.

Printing Types4

Printing Types4


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8 Blotch Prints

It is one in which thebackground color is

created by printing rather than dyeing. The groundand pattern design colorsare printed onto a white

cloth. One of theproblems with blotchprints is that largebackground color areas of

the print are not coveredwith the full depth of color.

Printing Types4

Printing Types4


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8 Warp Prints

This involves printingthe warp yarns of afabric before weaving.The fabric is wovenwith a solid color filling, usually white.The result is a soft,shadowed, blurreddesign on the fabric.These prints are foundon high quality, costlyfabrics because itrequires careful,meticulous labor.

Printing Types

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8 Flock Prints Tiny particles of fiber are

made to adhere to a fabricsurface in conformanceto a particular design.Rayon and nylon fibersare typically used for

flocking. The ability of flocked fibers towithstand dry cleaningand/or laundry dependson the adhesive.Adhesives with excellentfastness to cleaningprocesses are used.

Printing Types

Printing Types4


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8 Burn-out Prints

This involves printing

with a chemical that willdestroy the fiber in thepatterned design printarea. In fabrics that are

made with blendedyarns, the burn-outchemical will destroyone fiber and leave the

other undamaged.Unusual and interestingfabrics can be createdby this method.

Printing Types

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8 Duplex Prints

These are fabrics inwhich both sides of thefabric are printed.They are made toimitate more costlywoven yarn-dyeddesign effects such asstripes, checks andplaids. They are rarely

used because of thehigh cost of printingboth sides of a fabric.

Printing Types

Printing Types4


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8 Pigment Print

They are direct prints made with pigments. The processis called dry printing as distinguished from wet (dye)printing. The pigment print area will be slightly stiffer and bit thicker than the non-print area. They are theleast costly type of print to produce.

Printing Types

TYPESPrinting4


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Printing

8 Engineered Prints These are prints that have two or more distinct

designs, each located in separate areas of the fabric

and each designed to become a specific part of agarment. Engineered prints include fabrics whosedesigns are especially pre-established topermitmaking a garment in a particular stylized effect.


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Dyeing / PrintingProblems andRemedies

5

Dyeing and Printing Problems5


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Design lines in printed fabrics that are meant to be sharpdemarcations of color but that are muted or blurred.Fuzzy Pattern

A change of shade in dyed fabric caused by the chemicalreaction of certain disperse dyes with atmosphericcontaminants such as burnt gas fumes and ozone.

Fume Fading

A change of fabric color caused by localized abrasivewear, such as that occurring at collar points or garmentcreases.

Frosting

The loss of color brilliance through exposure to factorssuch as sunlight or cleaning agents.Fading

The transference of color from one fabric to another byrubbing.Crocking

Color is discharged into a liquid medium and transfers toanother fabric.Color Bleeding

A horizontal off-shade band across the fabric. Usuallyfound in knit fabrics, the problem is caused by a defect inthe yarn, uneven tension in knitting, or other factors thatproduce a color band when the fabric is dyed.

Barr

y g g

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Weak areas in fabric resulting from chemical damage, whichmay be produced by improper bleaching, chemical spills, or improperly applied coloring or finishing agents.

Tender Spots

The unintentional variation in color within a piece of fabric

or a garment.Shading

Lacking color alignment. In printing fabrics, the color separation is imperfect, producing a situation in which thedifferent color components of the design are not aligned.

Off Register

Lacking trueness. In printing, the design is transferred tothe fabric so the design of the fabric is not aligned with the

yarns.

Off Grain

The transfer of color from one area of the fabric to another.Migration

A phenomenon, also known as flare, that is observed whenmaterials are viewed under different light sources. Thespectral reflectance curves are not identical, so the viewer sees one color under one light source (incandescent) and adifferent color under another light source (fluorescent).

Metamerism

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Finishing

6

Finishing6


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8 Finishing is a general term for a magnitude of processes and treatments that a fabric may undergoafter it has been made (woven or knitted) and colored(dyed or printed).

8 It is the final processing of the cloth. Its purpose isto make the fabric more suitable for its intended enduse.

8 Textile finishes can be classified as aestheticfinishes and functional finishes .

8 They are also categorized as chemical finishes andmechanical finishes .

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Finishing Aesthetic Finishes6


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8 These are finishes which change the appearance,drapability and hand (feel) of fabrics includingparchmentizing, softeners, and stiffeningfinishes.

8 Finishes that alter or create texture include burn-out designs, embossing, pliss, raised fiber surfaces (brushing, gigging, napping, sueding,and flocking).

8 Finishes that alter fabric luster include beetling,

calendering (simple, glazed, moir, schreinering),optical finishes (delusterants, and opticalbrighteners).

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8 These are finishes which improve the performance properties of fabrics.

8

Finishes that enhance care properties include durablepress, soil-release, stain- and soil-resistant finishes.8 Finishes that provide comfort and safety include

antistatic, chemical-protective, absorbent, flame

resistance, water-repellent and waterproof finishes.8 Finishes that alter durability include abrasion-

resistant, slip resistant, and shrinkage control.8

Finishes that provide environmental protectioninclude antimicrobial finishes, fume fading inhibitors,metallic and plastic coatings, and mothproofing.

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8

Finishing that Changes Appearance, Drapability and Hand Parchmentizing A finishing process to give cellulosic fabrics such

characteristics as transparency, linen-like hand, and texture .The fabric is immersed briefly in an acid bath under controlled conditions and then quickly neutralized. Thisfinish is most effective on mercerized cotton.

Softening Softening agents are frequently used to improve the hand and

drape of fabric . The most commonly used softeners are oils,fats, wax emulsions, soaps and synthetic detergents, andsilicone compounds. Silicone compounds produce relativelydurable softening .

Stiffening Some fabrics need to be made stiffer and more crisp than

they would otherwise be in order to meet an intended enduse. Stiffening may be done by any of several chemicalfinishes, all applied by pad and either dried or cured. Starchis widely used but starch finishes are temporary.

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8 Finishes that Alter or Create Texture Pliss

This is a permanent finish , produced on cotton by thetreatment of sodium hydroxide to produce a puckered or crinkled fabric . Sodium hydroxide is printed on the fabric inthe form of paste and the fabric shrinks only where thepaste is applied. Acetate, rayon, and manufactured fabrics

with a puckered effect can be produced by chemicaltreatment or heat setting.

Embossing

This is a process to produce a raised design or pattern inrelief on fabrics by passing the cloth between hot engravedrollers that press the design into the fabric. In thermoplasticfabrics (polyester, nylon) embossing is permanent. In other fabrics, resin finishes are used to create a durable effect.

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8 Finishes that Alter or Create Texture Diagram of Embossing Rolls

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8 Finishes that Alter or Create Texture

Raised Fiber Surface

Fabric surfaces can be raised by brushing,gigging, napping, and sueding . Fabrics must bemade of staple-fiber yarns with low twist and lubricated to ease the extraction of fiber ends fromthe cloth .



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8 Finishes that Alter or Create Texture Napping

Napping uses a series of 24-30 cylinders covered withfine metal wires bent into small hooks , to produce athick, raised fiber surface on fabrics produced fromloosely twisted staple-fiber yarns. A fabric can benapped on a single side or both. The nap maybebrushed and/or sheared to make it even. Napping isused on broadcloth, flannel, and blankets

Sueding

A process similar to napping, it is a mechanical finishthat produces a soft, suede-like surface on the fabric.Instead of rotating, bristled wire covered brushes usedin napping, the rotating cylinders used for sueding

consist of a sandpaper-like material .



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8 Finishes that Alter or Create Texture Diagram of Napping Process



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8

Finishing that Alter Fabric Luster Calendering

A finishing process producing a flat, glossy, and smooth surface by passing the fabric under pressurebetween cylinders. The greater the heat and pressure,the higher the luster. Calender finishes include cir,glazing, moir, and schreinering.

Cir

Cir is a highly polished fabric produced by impregnating the fabric with wax or a thermoplastic material and then passing it through friction rollers.The resultant fabric is highly lustrous and takes on apopular wet look. When thermoplastic fiber fabricsare cir finished, the fabric becomes moderately water repellent due to flattening and partial fusing of fibers.



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8 Finishing that Alter Fabric Luster Glazing

A process that produces a smooth, high polish on thesurface of the fabric. The material is treated with variousmaterials including starch, paraffin, and shellac. Threerollers are used; the center roll is cotton-padded or paper,and the other two are metal. The metal rolls operate at avery high speed, and the other roll turns more slowly. Thepolish is created by the friction of the rolls .

Moir A moir finish is characterized by a soft luster and an

optical effect , which is created by interference between lightrays reflected from the crushed and uncrushed parts of the

fabric. Two layers of identical fabric are placed face to faceand then subjected to heat and pressure whereby a patternof parallel lines formed by the weft yarns of each fabric isimpressed upon the weft yarns of the opposing fabric .



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8 Finishing that Alter Fabric Luster Schreinering

A finishing process where the fabric is passed under pressure between an engraved steel calender roller and a smooth roller. The engraved roller has 180-360 fine lines embossed. This process flattens thefabric and produces fine lines on the surface whichincreases the light reflection to create a soft silk-likeluster.



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8 Finishing that Alter Fabric Luster Optical Finishes Delusterants

A process of dulling the luster of manufactured fibers,yarns, or fabrics with pigments or chemical treatment. Inmost manufactured fibers, pigment is introduced in thespinning solution to reduce luster. Delusterants such asbarium salts, zinc oxide, aluminum oxide and china clay canalso be applied to yarns and fabrics.

Optical Brighteners

Optical brighteners are used in finishing to maintain whiteand bright fabrics. They adhere to the fabric and create an

appearance of whiteness or brightness by the way theyreflect light; they absorb ultraviolet light and reflect it asvisible blue light.



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8 Finishing that Enhance Care Properties

Durable Press

This finish provides garments with shape retention,durable pleats and pressed creases, durably smoothseams, and wrinkle resistance.

There are two methods:1) post-cure technique in which the garment rather than

the fabric is cured and heat-set after construction or

2) flat or precured technique in which the piece goodsare finished and cured. Almost all fabrics for durablepress are blends of cellulosic fibers and polyester.



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8 Finishing that Enhance Care Properties Soil Release

A finish that increases the absorbency of a fabric, and which makes it easier to remove soil and stains inwashing. This finish (1) allows the stain to leave thefabric faster; (2) increases wicking action for greater comfort; (3) makes fabric dry-cleanable; and (4)maintains brightness after repeated laundering.

Stain- and Soil-resistant Finishes

Stain- and soil-resistant finishes resist staining. Stain-and soil-resistant finishes reduce the rate of soil

deposition on a fabric either by creating an electriccharge that repels the soil or by producing a smoothsurface to which soil will not adhere. Fabrics treatedwith such finishes are therefore easily cleaned.



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8 Finishing that Alter Durability Abrasion-resistant Finish

Abrasion resistance can be imparted by an acrylic resin;

however, some resins are too soft to be effective andsome are too hard and introduce brittleness to the fabric.These resins bind the fibers more firmly to the yarns.Some fiber such as nylon have inherent resistance toabrasion. Abrasion-resistant finishes are used on fabrics

subject to prolonged abrasive wear such as pockets,waistband lining, and hatbands .

Slip-resistant Finishes

Finishes applied to a fabric to reduce or eliminate yarnslippage and reduce seam fraying are called antislip, slip- resistant, or nonslip finishes. Products such as rosins(they have poor washfastness), colloidal dispersions of silica (they reduce surface smoothness but are notdurable), and formaldehyde resins (they are durable) arecommonly used.



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8 Finishing that Alter Durability Shrinkage Control There are Two Kinds of Fabric Shrinkage :

Relaxation ShrinkageThis occurs because the fibers and yarns are under tensionwhen the fabrics are made. Later when the fabric is wet in atensionless condition, relaxation occurs.

Progressive ShrinkageThis occurs each time a fabric is laundered. Unlikerelaxation shrinkage which occurs only once, progressiveshrinkage continues and the fabric shrinks a bit more with

each laundering. Of the major fibers, only wool and viscoserayon are subject to progressive shrinkage .

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8 The factors that control shrinkage in fabrics or garments are: Construction: A tighter fabric construction reduces

potential shrinkage

Yarn twist: Optimum twist (based on yarn size) is veryimportant for controlling shrinkage and torque.

Type of Weave or Knit: Pain weave of Jersey knit show

more resistance to shrinkage than other types. Tension During Sewing of Garments: Uneven or too much

sewing tension can lead to differential shrinkage causingpuckering in the seam areas.

Stability of Fiber and Yarns: Improper stabilization couldlead to excessive shrinkage especially in blends wheresynthetic fiber shrinks differentially than the cellulosicfibers.

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Illustration of Shrinkage on Woven Fabric Causedby Fiber and Yarn Swelling

Loomstate Fabrics

Fabric After Washing



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8 Finishing that Alter Durability Shrinkage Control Compressive Shrinkage (Relaxation Method)

Used for woven cotton, tubular knit cotton, linen and rayon;the method consists of mechanically compressing thefabric lengthwise by overfeeding onto a large roller withdamp blankets. Sanforized is a well known trade mark for fabrics treated by this method.

Heat Set (Relaxation Method) Used for fabrics from thermoplastic fibers such as nylon,

polyester and acrylic; it is based on the principle thatthermoplastic materials will become stabilized in their

configuration in which they happen to be when heated totheir softening temperature.



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8 Finishing that Alter Durability Shrinkage Control Sponging (Relaxation Method)

Used for woolen and worsted fabrics; it consists of thoroughly wetting the fabric with water or steam andallowing the material to dry slowly in a relaxed tensionlessstate. This does not make wool washable or shrink-proof;it permits wool to be steam pressed or caught in rainwithout severe shrinking.

Resin Treatments (Relaxation Method )

Used for fabrics of rayon and cotton; it involvesimpregnating rayon and cotton with resins and then curing

which stabilizes the fabric and thus reduces its tendencyto distort. Resins also provide crease resistance. It ispreferable to hand wash resin treated rayon fabrics.

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Felt Blanket Principle

Illustration of the Felt Blanket Machine Principle

Compressive ShrinkageFinishing6


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Rubber Belt Principle

Diagram of the Rubber Belt Principle

Shrinkage Controlof Knit FabricsFinishing6


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Belt Principle for Imparting Mechanical Shrinkage for Knits

Shrinkage Controlof Knit FabricsFinishing6


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8 For open-width knit fabricsbased on cavity typeoverfeeding

The Micrex Process



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8 Finishing that Provide Comfort and Safety Antistatic

A finish that helps reduce or eliminate static buildup infabrics . They are chemical compounds that, whenapplied to a fabric, reduces or eliminates theaccumulation of static electricity. This may be added tothe fiber lubricant or to yarn during spinning, by

spraying, or in a final rinse, or in pad dyeing. Fabricsofteners used in home laundering also reduce static.

Chemical-protective Finishes

These are finishes that prevent penetration of herbicideor pesticide through clothing and prevent easy removal by laundering of any pesticide on the surface of clothing.All cotton fabrics are better than polyester becausepesticides are absorbed by polyester but not cotton.



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8 Finishing that Provide Comfort and Safety Flame Retardant Finish

For most part, fabrics treated with these finishes burn in

the direct path of flame but self-extinguish when the sourceof flame is removed.

Unfortunately, use of these finishes result in stiffening and loss of fabric drapability, strength loss, loss of finish in

laundering (nondurable), and ineffectiveness whenlaundered in household bleach, soaps, or water softeners.

Some of the commonly used flame-retardant treatmentsinclude Pyrovatex CP (for cellulose and its blends), THPC(used extensively for childrens sleepwear), Firestop(trademarked by Cotton Incorporated; used in cellulose andits blends), Fyrol 76, TM-DABT (for 100% cotton and poly-cotton blends), Proban (cellulose blends), Spartan,Flamegard, Glotard, Fireway, Caliban, and Protogard.



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8 Finishing that Provide Comfort and Safety Water and Stain Repellent Finishes

They are chemical finishes that resist the penetration of water through the fabric but permit the passage of air or moisture. The principle behind this ability is that yarnsrather than fabric are coated with repellent chemicals.Water repellent finishes can be non-durable, durable, andrenewable.The principle types include wax emulsions,

resins (renewable), silicone compounds (durable), andzirconium compounds (non-durable).

Waterproof Finishes These are finishes that resist wetting and the penetration

of water. Waterproof fabrics are generally woven tightlyand coated with rubber, plastic (usually vinyl), linseedoil, cellulose esters, or other compounds. Fabrics arenon-permeable to air, possess a firm non-drapable handand are not comfortable as wearing apparel.



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8 Finishing that Provide Environmental Protection Antimicrobial Finish

They are applied to fabrics to prevent growth of

microorganisms . They thereby control the spread of disease and reduce the danger of infection; help to inhibitthe development of unpleasant odors from perspiration andother soils; and reduce damage to fabrics from mildew-producing fungi and rot-producing bacteria. These finishes

may be durable or renewable. Pacificate and Sanitizedare two well known trademarks for this finish.

Fume Fading Inhibitors Some colors fade, particularly disperse dyes on acetate,

caused by exposure to oxides of nitrogen in theatmosphere. Simple alkaline substances such as borax aresometimes used as after-treatments, but they are notpermanent.



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8 Finishing that Provide Environmental Protection Metallic and Plastic Coatings

Metallic and plastic coatings are applied to the back of

fabrics. Aluminum coatings, modify the warmth andcoolness of fabrics, are used for drapery lining. Plasticcoatings help reduce the amount of soil that penetratesthe fabric and delay the passage of heat through thefabric. One problem with coatings are they may peel or

crack off the substrate. Mothproofing Finish

Moth larvae and carpet beetles are known to attackanimal-fiber fabrics. Mothproofing is a chemical that is

added to the dyebath during dyeing of wool fabrics.Treated wool fabrics and silk fabrics are less susceptibleto damage by moths and other insects. Finishes basedon pyrethroids and pyrimidines are among the mostsuccessful products used for mothproofing.

Finishing6 Nano-Care


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8 The principles of nanotechnology are utilized to createexceptional performance in everyday items: apparel,home furnishings, commercial interiors, industrial

fabrics.8 Nanotechnology provides the ability to work on a nanoor submicron scale to create intelligent structures thatare stronger and have fundamentally different,performance-enhancing molecular organizations.

8 NANO-CARE fabric protection imparts arevolutionary, carefree quality to wrinkle resistantfabric that minimizes stains, offers superior liquidrepellency and maintains wrinkle resistance. NANO-CARE enhanced fabrics cause water and oil spills tobead up and roll off fabric without penetrating thefibers.

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8 Key Features

Superior Stain, Water, And Oil Repellency

Resists Wrinkles Breathable Fabric

Preserves Original Hand

Easy Care

Durable Performance


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