Dyeing, Printing and Finishing: A Guide to Textile Preparation, Application and Process Optimization

Dyeing, Printing
and Finishing

VESTEX
Srini Venkataraman
Dr. Sandeep Khatua
March 2006
Bureau Veritas
Consumer Products Services
For the benefit of business and people

Summary 1) Preparatory Process and
Their Importance
2) Dyeing
3) Dyeing Techniques
4) Printing
5) Dyeing / Printing Problems
and Remedies
6) Finishing

2

1
Preparatory Process
and Their Important

3

1 Preparation Objectives

8 Remove impurities (both natural and/or those added
during 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.

Bureau Veritas Consumer Products Services 4

1 Preparation Importance

8 The importance of adequate and uniform preparation
prior 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 dyeing
are the result of improper preparation.
8 Preparation procedures may vary greatly from one
fiber type to another. While natural fiber usually
require extensive scouring and bleaching, synthetic
fibers may need only a mild scouring.


1 Preparation

8 Important Preparatory Steps for Cotton Fabric
• Singeing
• Desizing
• Scouring
• Bleaching
• Mercerizing


1 Preparation Singeing

8 Removes superficial hairiness from yarns, lint, loose
yarns, and surface dirt from the face of the fabric and
therefore provides more even surface for dyeing.
8 It also reduces formation of pills, or balls of fiber, on
the fabric.
8 After the surface of the fabric is raised by brushing,
the protruding fiber ends are burned off by the
singeing process. In this process the fabric is passed
through the small gas flame.
8 Note: Consumers may detect increased pilling in
improperly singed Cotton fabrics. When Cotton
blends are singed, care must be taken to avoid
overheating the thermoplastic fibers.


1 Preparation Desizing

8 Prior to weaving, Cotton warp yarns are coated with
sizing materials to provide them with additional
strength, and resistance to abrasion. The most
common sizing materials used are different kinds of
starches, and various grades of partially hydrolyzed
polyvinyl alcohol.
8 Enzymes are often used for the effective removal of
starches.
8 The main advantage of enzyme desizing is that there
is no risk of damaging the fibers. However, enzymatic
desizing is relatively expensive since it can not be
combined with other preparatory operations.


1 Preparation Scouring

8 This cleaning treatment, often referred to as alkali boil-
off, removes most of the Cotton’s impurities, which
includes natural and other impurities as well as sizing
residues that were not removed during desizing.
8 In scouring the fabric is treated with a strong alkali
solutions, close to or above the boil, for 1-2hours. A
hot rinse is needed to remove the emulsified
impurities. The final rinse may include a small amount
of acetic acid if the fabric has to be neutralized.
8 Manmade fibers, especially those that have been
heavily treated with spinning oils, are occasionally
scoured with solvents.


1 Preparation Bleaching

8 The purpose of Bleaching is to provide a uniform white
surface on a fabric. It is chemical oxidation that
destroys the colored impurities present.
8 Control of whiteness of bleached fabric is important to
wet processing that follow.
8 Hydrogen Peroxide is the chemical most commonly
used today for bleaching Cotton compared to Sodium
Chlorite
8 Open Width Method and Rope Method: Open width
method is widely used method especially when
bleaching blends of Cotton with heat-sensitive fibers in
order to avoid crease marks and other defects caused
by treating fabrics in the rope form.



Open Width Method



Rope Method


1 Preparation Mercerization

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 in
cross-section and it gains luster. Dye affinity and chemical
reactivity increase. Fabric becomes stronger and
smoother.
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 fabric
bandages, which need to conform to body shapes.


1 Preparation Mercerization

Note: Fabric Mercerization
is Cheaper than double
Mercerization which
provides a softer hand


1 Preparation Knit Fabric

8 Knitted fabrics are pre-relaxed to minimize
torque, puckering of seams, and shrinkage during
dyeing and drying. Conveyor type relaxation
dryers and / or compacting are used to minimize
residual fabric shrinkage.
8 After knitting, the lubricants (added to improve
“knitability”) must be removed with a water-based
or solvent scouring process.


1 Preparation Thermoplastic Fabrics

8 Heat-setting or thermosetting is a heat treatment applied
to 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 it
decreases its dye-ability, and therefore when performed
before 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 to
center which will show later as unlevel dyeing.


2 Dyeing

8 Dyeing is by far the most widely used means of
applying color to textiles.
8 Dyes, by definition, are soluble in the medium
in which they are applied, and the medium is
almost always water.


2 Dyeing Classification and Fibers

8 There are several different ways by which coloring
materials 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)


2 Dyeing How Dyeing Takes Place

Immerse Textile in Dye-bath All Dye is in Bath

Apply Heat, Time, Chemicals Fabric Most of the Dye
Now on Textiles
to Drive Dye into Textiles

Fabric
Unfixed Surface
Rinse to Remove Surface Dye Dye Removed


2 Dyeing How Dyeing Takes Place

Polymer Morphology Inside a Fiber


2 Dyeing

Typical Reactive Dyeing Process on Cotton Woven


2 Dyeing

8 The Major System Variables
• Textile substrate
• Application method
• Dye selection and formulation
8 Need to Control These Variables in Order to Achieve:
• Target shade predictability
• Required fastness
• Efficiency in terms of cost of materials and plant
occupancy


2 Dyeing

8 General Principles and Terms Met in Dyeing
1) 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 is
allowed to proceed under the same conditions for a
longer time, the shade of the dyed goods will remain the
same.
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


2 Dyeing Stages

8 Dyeing Can Be Done at Different Stages:
• Fiber Stage
• Yarn Stage
• Fabric Stage
• Garment Stage


2 Dyeing Stages


2 Dyeing Fiber

8 Stock Dyeing
• Masses of loose fibers
are placed in large drums
into which dye is pumped
and circulated.
• Tweed fabrics with a
heather-like color effect
such as Harris tweed is
done using this method.


2 Dyeing Fiber

8 Producer or Solution Dyeing
• Colorant is added to the
spinning solution before the
polymer mix is extruded and
formed into a manufactured
fiber.
• This method is very desirable
when high colorfastness is
desired such as automotive
seating fabrics, carpeting etc.


2 Dyeing Yarn

8 Yarn Dyeing
• Yarns are immersed into a
dyebath prior to being made into
fabric.
• Loosely wound hanks can be
dyed (skein dyeing),
• Yarns wound into small tubes
called package can be dyed
(package dyeing), or
• The entire warp beam can be
immersed into dyebath (beam
dyeing).


2 Dyeing Yarn / Fabric Dyeing

8 Beam Dyeing
• Both yarn and fabric can be dyed by this process


2 Dyeing Fabric

8 Piece Winch (or beck) Dyeing
• Fabric pieces are sewn end to
end and this rope-like form is
dyed in a relaxed state.
• It is most widely used on
knitted, woolen and worsted
fabrics.


2 Dyeing Fabric

8 Piece Jet Dyeing
• Dyeing is done in a
closed, tube-like
system in which the
fabric passes through
a fast moving stream
of pressurized dye
liquor.
• It is primarily used for
fabrics prone to
felting.


2 Dyeing Fabric

8 Piece Jig Dyeing
• Fabric is treated in open
width and is passed
through the dye bath
rather than immersed in to
a dye bath and this is
repeated.
• There is a degree of
tension on the fabric and
is therefore used on
woven fabrics and not
knits.


2 Dyeing Fabric

8 Piece Pad Dyeing
• The dye solution is applied
by means of a padder and
the fabric in open form is
run through an open vat.
• The fabric is subject to
tension, so only selected
fabrics can be dyed.
• Advantages: System can
handle thousands of yards
and dye can be added
automatically to provide
consistency of dye color


2 Dyeing Garment

• Dyeing is done on
completed garments.
• Garments are placed in
a nylon bag and placed
in large tubs containing
dye bath.
• Garments having
differential shrinkage
among various
components may have
difficulty being dyed by
this method.


3
Dyeing Techniques

36

3 Dyeing Techniques Reactive

8 Reactive Dyeing
• The reactive dyes are water-soluble anionic dyes, which
react with hydroxyl groups of cellulose to become
covalently bonded to the fiber
• The chemical reaction between a reactive dye and a
cellulose 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 light
fastness).
• Susceptible to damage from chlorine bleaches


3 Dyeing Techniques VAT

8 The Vat dyes are insoluble organic compounds
that 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 to
cellulosic fibers, and can be applied to them.
3) Oxidation: Once inside the fibers, uniformly distributed,
the Vat dyes are then oxidized and converted back to
their original insoluble form.
4) Soaping: to achieve a stable shade.


3 Dyeing Techniques VAT

8 The soft water throughout the dyeing stage is a
must with Vat dyes, since the soluble Leuco
salts form insoluble salts with Calcium or
Magnesium ions as well as with transition
metals.
8 A wide choice of colors with good to excellent
colorfastness is available, although their
lightfastness may be somewhat inferior.


3 Dyeing Techniques Sulfur

8 Sulfur dyes are insoluble in water and their application
to cellulosic fibers resembles that of the Vat dyes in
principle. 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 are
available 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 with
mild alkali solutions.
8 Sulfur dyed fabrics have good colorfastness to washing
but are sensitive to chlorine bleaching. Lightfastness is
only fair but is adequate for most end uses not requiring
prolonged sunlight exposure.


3 Dyeing Techniques Direct

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 large
number of weak attractions between the dye and the fiber.
8 Direct dyes exhibit relatively good colorfastness to
sunlight, and some are considered to have excellent
lightfastness. However colorfastness to washing is poor
and therefore not appropriate for frequently washed
apparel.
8 The problem of poor washfastness can be improved to
some degree by formaldehyde after treatment.


3 Dyeing Techniques Disperse

8 The disperse dyes are non-ionic aromatic compounds
with 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 Dyeing
3) 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 an
area with gas heat.


3 Dyeing Techniques


3 Dyeing Techniques

Dyestuff Properties
Perspiratio
Ease of
Dyes Cost Washfastness Lightfastness Crockfastness n
Application
Fastness
Average
Acid Average Fair - Good Good Good Good
-
Average Average –
Basic Poor – Good Poor – Good Fair – Good Fair – Good
+ Fairly Difficult

Wet – Poor Poor –
Direct Cheap Easy Poor – Good Fair – Good
Dry – Good Good

Disperse Average Fairly Hard Good Good Fair – Good Fair – Good

Naphthol Average Hard Good Good Fair – Good Fair – Good

Average Good –
Average –
Reactive Excellent Good Fair – Good Fair – Good
+ Fairly Difficult
(if soaped)

Sulfur Cheap Fairly Difficult Good Fair – Good Good Good

Average Good – Good –
Vat Fairly Difficult Good Good
+ Excellent Excellent


3 Dyeing Techniques Blends

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 applied
to 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 with
these methods.
• Two-bath method offers better result on
Polyester/Cotton blends compared to One-bath
method.
• One-bath method is cheaper than Two-bath method.


3 Dyeing Techniques Blends

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 each
fiber type or variant accepts a different type of dye and
becomes a different color.
• The end product depends on the fiber arrangement in
the fabric. It may be a check, a plaid, a tweed, a stripe, a
muted color, a heather effect, or some other design.


3 Dyeing Techniques Pigment Coloration

8 Advantages
• Pigment coloration is economical because of limited
number of processing steps.
• Blends can be dyed a uniform shade with one operation
applicable 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 be
selected so that finish and binder react under
same conditions of pH and/or temperature.


3 Dyeing Techniques Pigment Coloration

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 variable
or pickup is high.


3 Dyeing Techniques Optical Brighteners

8 Optical brighteners, also called Fluorescent
Brighteners or Fluorescent Brightening Agents (FBA)
are colorless dyes that work by emitting visible light
when exposed to invisible ultra-violet light.
8 They are used to make white or light-colored fabrics
appear brighter. Mostly bleached white fabrics are
treated with these brighteners.
8 Fabrics and garments that are truly prepared for
dyeing should not contain brighteners. Optical
brighteners can interfere with some dyes by
competing for the "dye sites" on the fibers.


3 Dyeing Techniques Optical Brighteners

8 Optical brighteners have the property of absorbing ultra-
violet (UV) light and re-emitting energy in the form of
weaker energy, i.e. visible light (violet-blue light) so that
the yellow color of the material will appear white.
8 The chemical structures of these agents contain an
aliphatic carbon-carbon double bond, which is sensitive
to sunlight, oxidation, weathering, etc.
8 Therefore, these compounds do not have good fastness
properties, and tend to loose their ability to absorb UV
light over short periods of time in use.
8 The presence of high concentrations or improper
application or cheaper quality of fluorescent brighteners
could lead to yellowing of the material instead of
whitening.


4 Printing

8 The application of colorant in definite, repeated
patterns to fabric, yarn or sliver.
8 The different methods of printing include hand
screen, automatic screen, rotary screen, roller
and heat transfer.
8 Each method can be used to print one or more
print types.
8 These include direct, discharge and resist prints.


4 Printing

8 There are Three Methods of Printing:
• Screen Printing
• Roller Printing
• Heat-Transfer Printing


4 Printing Methods

8 Screen Printing
• This printing involves coating of a screen fabric (made
of nylon, polyester, or metal tightly mounted on a
wooden or metal frame) with an opaque nonporous film
with 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 separate
application of color. Also each color of the design
must be precisely located on the screen so that it
becomes properly placed and printed.


4 Printing Methods

8 Screen Printing
• Types of Screen Printing Include:
» Flatbed Screen - Hand or Automatic
» Rotary Screen


4 Printing Flatbed Screen

8 They are used primarily to print on flat
substrates
8 Consists of a bed or vacuum table that
holds the substrate in place during
printing, a carriage that holds the
printing screen, and a squeegee.
8 Printing takes place in three steps.
First, ink is poured on the screen, and
the screen is moved into position over
the substrate. Then the squeegee is
pressed against the mesh and drawn
over the image area to push ink through
the open areas of the screen onto the
substrate. Finally, the screen is lifted
away from the substrate.


4 Printing

Rotary Screen Printing Process


4 Printing Rotary vs Flatbed Screen

8 The equipment costs for Flatbed screen printing are
lower than other printing processes, but the rate of
production is usually slower.
8 Rotary printing is a continuous, stepless image
transfer method whereas flatbed printing is a two
step process.
8 Flatbed screen printing is good for small repeat
units or rigid stock printing (impossible to support
on rotary machine).
8 Rotary screen is best choice for coarse halftones
and specialty inks.


4 Printing Methods

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.


4 Printing Roller Printing Process


4 Printing Print Inks

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 goods
such as T-shirts, sweatshirts, jackets, and tote bags.
» Water-based ink is the ink of choice for the printing
of yard goods; either in piece form or on the roll.


4 Printing Plastisol Printing

8 Plastisol ink is a PVC based system that contains no
solvent.
8 It is thermoplastic that requires specific heat and time for
complete curing. Failure to follow proper curing guidelines
will result in an “under Cure” of the print and therefore will
cause poor washfastness, and/or a resistance to abrasion.
8 The performance of plastisol can be affected by addition
of additives such as Extenders, plasticizers, reducers and
resins.
8 Problems such as fading, pulling away and/or cracking
can occur if additives are used properly.
8 If not cured properly, phthalates (a commonly used
plasticizer) could cause skin irritation.


4 Printing Plastisol Inks

8 Advantages of Plastisol Inks
• User-friendly, very easy to manage
• Can be left in the screen for extended periods of time
without 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 increased
production speeds
• Can be printed on light and dark fabrics
• Disposal of waste plastisol is a simple process


4 Printing Water-based Links

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 equipment
that has very large drying (curing) capacity.
• Good choice where ink penetration is desirable such as
in towel printing


4 Printing Plastisol vs. Water-based Links

Ease Waste
Curing of Opacity Hand Cost Ink
Printing Recovery
Low- Medium - Moderate -
Plastisol Easy Fair Excellent
High Heavy High
Low - Low -
Water-based Hard Easy Soft Fair
Medium Moderate

Plastisol Water-based
T-shirts, light colored Excellent Excellent
T-shirts, dark colored Good Poor
Nylon Jackets Good Fair
Towels Poor Excellent
Yardage Poor Excellent


4 Printing Metallic Prints

8 Metallic inks are simply finely ground metal and/or
plastic flakes that are suspended in a clear plastisol
base.
8 can be used as accents in a design or as the entire
print.
8 One of the biggest problems with metallics is that
some brands that use metal flakes dull and tarnish
badly after the first washing but small plastic flake
that doesn't tarnish
8 A popular technique to improve the washability and
brightness of metallic prints is to add 5% nylon
jacket bonding agent to the mixture. This helps seal
the metal particles and minimize the tarnishing.


4 Printing Glitter

8 Glitter ink is made up of small mylar flakes that are
suspended 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 ink
for a design that need a little glitz. It works well on both light
and dark shirts because the glitter flake makes the ink very
opaque.
8 The clear base of the glitter mixture will need to be cured
just like a normal plastisol except the ink deposit is so thick
that a longer tunnel time is very important.
8 Glitter washes very good and will flake just a little. Unlike
metallic ink that will dull, glitter retains it's brilliance
because the flake is mylar and does not tarnish like some
metallics.

4 Printing Methods

8 Heat-Transfer Printing
• This is also called thermal transfer printing.
In this method the design is first printed on
paper with printing inks containing
disperse dyes.
• The printed paper (called transfer paper) is
placed on the fabric and passed through
heat-transfer printing machine at about
400°F. Under this temperature, the dye on
the paper sublimates and is transferred
onto the fabric.
• Disperse dyes is the only class of dyes that
can be sublimated and used for this
method of printing.


4 Printing

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


4 Printing Types

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


4 Printing Types

8 Direct Print
• Also called application
print. Design is printed
directly onto a white
cloth or a previously
dyed fabric. They are
the most popular print
types.


4 Printing Types

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 which
removes the color of the originally dyed fabric. Discharge prints can
be made with rollers and screen methods. They are not widely used
because production costs are high.


4 Printing Types

8 Resist Print
• It involves a two step procedure: (1) printing a pattern design
on a white fabric with a chemical that will prevent penetration
of dyes; and (2) piece dyeing the fabric. The result is a dyed
background with a white patterned area.


4 Printing Types

8 Blotch Prints
• It is one in which the
background color is
created by printing rather
than dyeing. The ground
and pattern design colors
are printed onto a white
cloth. One of the
problems with blotch
prints is that large
background color areas of
the print are not covered
with the full depth of
color.


4 Printing Types

8 Warp Prints
• This involves printing
the warp yarns of a
fabric before weaving.
The fabric is woven
with a solid color
filling, usually white.
The result is a soft,
shadowed, blurred
design on the fabric.
These prints are found
on high quality, costly
fabrics because it
requires careful,
meticulous labor.


4 Printing Types

8 Flock Prints
• Tiny particles of fiber are
made to adhere to a fabric
surface in conformance
to a particular design.
Rayon and nylon fibers
are typically used for
flocking. The ability of
flocked fibers to
withstand dry cleaning
and/or laundry depends
on the adhesive.
Adhesives with excellent
fastness to cleaning
processes are used.


4 Printing Types

8 Burn-out Prints
• This involves printing
with a chemical that will
destroy the fiber in the
patterned design print
area. In fabrics that are
made with blended
yarns, the burn-out
chemical will destroy
one fiber and leave the
other undamaged.
Unusual and interesting
fabrics can be created
by this method.


4 Printing Types

8 Duplex Prints
• These are fabrics in
which both sides of the
fabric are printed.
They are made to
imitate more costly
woven yarn-dyed
design effects such as
stripes, checks and
plaids. They are rarely
used because of the
high cost of printing
both sides of a fabric.


4 Printing Types

8 Pigment Print
• They are direct prints made with pigments. The process
is 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 the
least costly type of print to produce.


4 Printing TYPES

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 a
garment. Engineered prints include fabrics whose
designs are especially pre-established topermit
making a garment in a particular stylized effect.


5
Dyeing / Printing
Problems and
Remedies

81

5 Dyeing and Printing Problems

A horizontal off-shade band across the fabric. Usually
found in knit fabrics, the problem is caused by a defect in
Barré the yarn, uneven tension in knitting, or other factors that
produce a color band when the fabric is dyed.
Color Color is discharged into a liquid medium and transfers to
Bleeding another fabric.

The transference of color from one fabric to another by
Crocking rubbing.

The loss of color brilliance through exposure to factors
Fading such as sunlight or cleaning agents.
A change of fabric color caused by localized abrasive
Frosting wear, such as that occurring at collar points or garment
creases.
A change of shade in dyed fabric caused by the chemical
Fume Fading reaction of certain disperse dyes with atmospheric
contaminants such as burnt gas fumes and ozone.
Design lines in printed fabrics that are meant to be sharp
Fuzzy Pattern demarcations of color but that are muted or blurred.


5 Dyeing and Printing Problems

A phenomenon, also known as flare, that is observed when
materials are viewed under different light sources. The
Metamerism spectral reflectance curves are not identical, so the viewer
sees one color under one light source (incandescent) and a
different color under another light source (fluorescent).

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

Lacking trueness. In printing, the design is transferred to
Off Grain the fabric so the design of the fabric is not aligned with the
yarns.
Lacking color alignment. In printing fabrics, the color
Off Register separation is imperfect, producing a situation in which the
different color components of the design are not aligned.
The unintentional variation in color within a piece of fabric
Shading or a garment.
Weak areas in fabric resulting from chemical damage, which
Tender Spots may be produced by improper bleaching, chemical spills, or
improperly applied coloring or finishing agents.


6 Finishing

8 Finishing is a general term for a magnitude of
processes and treatments that a fabric may undergo
after it has been made (woven or knitted) and colored
(dyed or printed).
8 It is the final processing of the cloth. Its purpose is
to make the fabric more suitable for its intended end
use.
8 Textile finishes can be classified as aesthetic
finishes and functional finishes.
8 They are also categorized as chemical finishes and
mechanical finishes.


6 Finishing Aesthetic Finishes

8 These are finishes which change the appearance,
drapability and hand (feel) of fabrics including
parchmentizing, softeners, and stiffening
finishes.
8 Finishes that alter or create texture include burn-
out designs, embossing, plissé, raised fiber
surfaces (brushing, gigging, napping, sueding,
and flocking).
8 Finishes that alter fabric luster include beetling,
calendering (simple, glazed, moiré, schreinering),
optical finishes (delusterants, and optical
brighteners).


6 Finishing Functional Finishes

8 These are finishes which improve the performance
properties of fabrics.
8 Finishes that enhance care properties include durable
press, 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 protection
include antimicrobial finishes, fume fading inhibitors,
metallic and plastic coatings, and mothproofing.



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. This
finish 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, and
silicone compounds. Silicone compounds produce relatively
durable softening.
• Stiffening
» Some fabrics need to be made stiffer and more crisp than
they would otherwise be in order to meet an intended end
use. Stiffening may be done by any of several chemical
finishes, all applied by pad and either dried or cured. Starch
is widely used but starch finishes are temporary.



8 Finishes that Alter or Create Texture
• Plissé
» This is a permanent finish, produced on cotton by the
treatment of sodium hydroxide to produce a puckered or
crinkled fabric. Sodium hydroxide is printed on the fabric in
the form of paste and the fabric shrinks only where the
paste is applied. Acetate, rayon, and manufactured fabrics
with a puckered effect can be produced by chemical
treatment or heat setting.
• Embossing
» This is a process to produce a raised design or pattern in
relief on fabrics by passing the cloth between hot engraved
rollers that press the design into the fabric. In thermoplastic
fabrics (polyester, nylon) embossing is permanent. In other
fabrics, resin finishes are used to create a durable effect.



• Diagram of Embossing Rolls



• Raised Fiber Surface
» Fabric surfaces can be raised by brushing,
gigging, napping, and sueding. Fabrics must be
made of staple-fiber yarns with low twist and
lubricated to ease the extraction of fiber ends from
the cloth.



• Napping
» Napping uses a series of 24-30 cylinders covered with
fine metal wires bent into small hooks, to produce a
thick, raised fiber surface on fabrics produced from
loosely twisted staple-fiber yarns. A fabric can be
napped on a single side or both. The nap maybe
brushed and/or sheared to make it even. Napping is
used on broadcloth, flannel, and blankets
• Sueding
» A process similar to napping, it is a mechanical finish
that produces a soft, suede-like surface on the fabric.
Instead of rotating, bristled wire covered brushes used
in napping, the rotating cylinders used for sueding
consist of a sandpaper-like material.



• Diagram of Napping Process



8 Finishing that Alter Fabric Luster
• Calendering
» A finishing process producing a flat, glossy, and
smooth surface by passing the fabric under pressure
between cylinders. The greater the heat and pressure,
the higher the luster. Calender finishes include ciré,
glazing, moiré, and schreinering.
• Ciré
» Ciré 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 a
popular “wet look.” When thermoplastic fiber fabrics
are ciré finished, the fabric becomes moderately water
repellent due to flattening and partial fusing of fibers.



• Glazing
» A process that produces a smooth, high polish on the
surface of the fabric. The material is treated with various
materials including starch, paraffin, and shellac. Three
rollers are used; the center roll is cotton-padded or paper,
and the other two are metal. The metal rolls operate at a
very high speed, and the other roll turns more slowly. The
polish is created by the friction of the rolls.
• Moiré
» A moiré finish is characterized by a soft luster and an
optical effect, which is created by interference between light
rays reflected from the crushed and uncrushed parts of the
fabric. Two layers of identical fabric are placed face to face
and then subjected to heat and pressure whereby a pattern
of parallel lines formed by the weft yarns of each fabric is
impressed upon the weft yarns of the opposing fabric.



• 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 the
fabric and produces fine lines on the surface which
increases the light reflection to create a soft silk-like
luster.



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. In
most manufactured fibers, pigment is introduced in the
spinning solution to reduce luster. Delusterants such as
barium salts, zinc oxide, aluminum oxide and china clay can
also be applied to yarns and fabrics.
• Optical Brighteners
» Optical brighteners are used in finishing to maintain white
and bright fabrics. They adhere to the fabric and create an
appearance of whiteness or brightness by the way they
reflect light; they absorb ultraviolet light and reflect it as
visible blue light.



8 Finishing that Enhance Care Properties
• Durable Press
» This finish provides garments with shape retention,
durable pleats and pressed creases, durably smooth
seams, 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 goods
are finished and cured. Almost all fabrics for durable
press are blends of cellulosic fibers and polyester.



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 in
washing. This finish (1) allows the stain to leave the
fabric 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 electric
charge that repels the soil or by producing a smooth
surface to which soil will not adhere. Fabrics treated
with such finishes are therefore easily cleaned.



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 and
some 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 to
abrasion. 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 yarn
slippage 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 not
durable), and formaldehyde resins (they are durable) are
commonly used.


8 Finishing that Alter Durability ― Shrinkage Control
• There are Two Kinds of Fabric Shrinkage:
» Relaxation Shrinkage
This occurs because the fibers and yarns are under tension
when the fabrics are made. Later when the fabric is wet in a
tensionless condition, relaxation occurs.
» Progressive Shrinkage
This occurs each time a fabric is laundered. Unlike
relaxation shrinkage which occurs only once, progressive
shrinkage continues and the fabric shrinks a bit more with
each laundering. Of the major fibers, only wool and viscose
rayon are subject to progressive shrinkage.


? ? Shrinkage Control

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 very
important 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 causing
puckering in the seam areas.
• Stability of Fiber and Yarns: Improper stabilization could
lead to excessive shrinkage especially in blends where
synthetic fiber shrinks differentially than the cellulosic
fibers.


? ? Shrinkage Control

Illustration of Shrinkage on Woven Fabric Caused
by Fiber and Yarn Swelling

Loomstate Fabrics

Fabric After Washing



• Compressive Shrinkage (Relaxation Method)
» Used for woven cotton, tubular knit cotton, linen and rayon;
the method consists of mechanically compressing the
fabric lengthwise by overfeeding onto a large roller with
damp 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 that
thermoplastic materials will become stabilized in their
configuration in which they happen to be when heated to
their softening temperature.



• Sponging (Relaxation Method)
» Used for woolen and worsted fabrics; it consists of
thoroughly wetting the fabric with water or steam and
allowing the material to dry slowly in a relaxed tensionless
state. This does not make wool washable or shrink-proof;
it permits wool to be steam pressed or caught in rain
without severe shrinking.
• Resin Treatments (Relaxation Method)
» Used for fabrics of rayon and cotton; it involves
impregnating rayon and cotton with resins and then curing
which stabilizes the fabric and thus reduces its tendency
to distort. Resins also provide crease resistance. It is
preferable to hand wash resin treated rayon fabrics.


6 Finishing Compressive Shrinkage

Illustration of the Felt Blanket Machine Principle

Felt Blanket Principle


6 Finishing Compressive Shrinkage

Diagram of the Rubber Belt Principle

Rubber Belt Principle


Shrinkage Control
6 Finishing of Knit Fabrics

Belt Principle for Imparting Mechanical Shrinkage for Knits


Shrinkage Control
6 Finishing of Knit Fabrics

The Micrex Process

8 For open-width knit fabrics
based on cavity type
overfeeding



8 Finishing that Provide Comfort and Safety
• Antistatic
» A finish that helps reduce or eliminate static buildup in
fabrics. They are chemical compounds that, when
applied to a fabric, reduces or eliminates the
accumulation of static electricity. This may be added to
the fiber lubricant or to yarn during spinning, by
spraying, or in a final rinse, or in pad dyeing. Fabric
softeners used in home laundering also reduce static.
• Chemical-protective Finishes
» These are finishes that prevent penetration of herbicide
or pesticide through clothing and prevent easy removal
by laundering of any pesticide on the surface of clothing.
All cotton fabrics are better than polyester because
pesticides are absorbed by polyester but not cotton.



• Flame Retardant Finish
» For most part, fabrics treated with these finishes burn in
the direct path of flame but self-extinguish when the source
of 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 when
laundered in household bleach, soaps, or water softeners.
» Some of the commonly used flame-retardant treatments
include Pyrovatex CP (for cellulose and its blends), THPC
(used extensively for children’s sleepwear), Firestop
(trademarked by Cotton Incorporated; used in cellulose and
its blends), Fyrol 76, TM-DABT (for 100% cotton and poly-
cotton blends), Proban (cellulose blends), Spartan,
Flamegard, Glotard, Fireway, Caliban, and Protogard.



• 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 yarns
rather than fabric are coated with repellent chemicals.
Water repellent finishes can be non-durable, durable, and
renewable.The principle types include wax emulsions,
resins (renewable), silicone compounds (durable), and
zirconium compounds (non-durable).
• Waterproof Finishes
» These are finishes that resist wetting and the penetration
of water. Waterproof fabrics are generally woven tightly
and coated with rubber, plastic (usually vinyl), linseed
oil, cellulose esters, or other compounds. Fabrics are
non-permeable to air, possess a firm non-drapable hand
and are not comfortable as wearing apparel.



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 inhibit
the development of unpleasant odors from perspiration and
other soils; and reduce damage to fabrics from mildew-
producing fungi and rot-producing bacteria. These finishes
may be durable or renewable. Pacificate and Sanitized
are 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 the
atmosphere. Simple alkaline substances such as borax are
sometimes used as after-treatments, but they are not
permanent.



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 and
coolness of fabrics, are used for drapery lining. Plastic
coatings help reduce the amount of soil that penetrates
the fabric and delay the passage of heat through the
fabric. One problem with coatings are they may peel or
crack off the substrate.
• Mothproofing Finish
» Moth larvae and carpet beetles are known to attack
animal-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 susceptible
to damage by moths and other insects. Finishes based
on pyrethroids and pyrimidines are among the most
successful products used for mothproofing.


6 Finishing Nano-Care

8 The principles of nanotechnology are utilized to create
exceptional performance in everyday items: apparel,
home furnishings, commercial interiors, industrial
fabrics.
8 Nanotechnology provides the ability to work on a nano
or submicron scale to create intelligent structures that
are stronger and have fundamentally different,
performance-enhancing molecular organizations.
8 NANO-CARE® fabric protection imparts a
revolutionary, carefree quality to wrinkle resistant
fabric that minimizes stains, offers superior liquid
repellency and maintains wrinkle resistance. NANO-
CARE® enhanced fabrics cause water and oil spills to
bead up and roll off fabric without penetrating the
fibers.


6 Finishing Nano-Care

8 Key Features
• Superior Stain, Water, And Oil Repellency
• Resists Wrinkles
• Breathable Fabric
• Preserves Original Hand
• Easy Care
• Durable Performance


Dyeing, Printing and Finishing: A Guide to Textile Preparation, Application and Process Optimization

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