printing Dyeing method (2)textile science.pptx

Department of Fabric & Apparel Science
Institute of Home Economics
University of Delhi

 Colour is a visual sensation. It results from
the reflection of certain visible light rays
that strike the retina of the eye and
stimulate the nerve cells of the eyes - nerves
send a message to the brain, which in turn,
produces the sensation of a specific colour.
 When all the visible light rays are reflected
we see white.
 When all the visible light rays are absorbed
we see black.

 Colour can be added to textile objects by application of
dyes. These dye molecules absorb light rays of selected
wavelengths causing the fabric surface to reflect light
rays which are not absorbed.
Dye is an organic compound composed of 2 components:
Dyes must be small particles that can be thoroughly
dissolved in water or any other carrier in order to
penetrate the fiber.
Chromophore:
• colour producing
component of dye
molecule. E.g.: azo group,
nitro group.
Auxochrome:
• slightly alter colour, add
solubility to the dye,
possible sight for bonding
with the fiber.

 It involves the following steps:
Migration
Adsorption
Absorption
Fixation

 Migration means movement of dyes from
solution form to the fabric surface.
 Adsorption is the process by which a solid holds
molecules of a gas or liquid or solute as a thin
film.
 Absorption is the diffusion of dye from surface
towards the centre of the fiber.
 Fixation is anchoring of the dye molecules by
covalent or hydrogen bonds or other physical
forces of a physical nature.

DYES FOR
COTTON/CELL
ULOSIC
DIRECT
DYES
VAT
DYES
SULPH-
UR DYES
AZOICS/
NAPHTHOL/
ICE COLOUR
DYES FOR
PROTEIN
FIBERS
ACID DYES
METAL
COMPLEX
CHROME
DYE/MORD-
ANT DYES
DISPERSE
DYES
DYES FOR
ACRYLIC,CELL-
ULOSIC AND
PROTEIN
BASIC DYES
(CATIONIC
DYES)
REACTIVE
DYES
DYES FOR
ACETATE,
ACRYLIC,NYL-
ON,POLYESTER
PIGMENTS

 When a dye is applied directly to the
fabric without the aid of an affixing
agent, it is called direct dyeing.
 Most commercially significant dye
class, complete colour range
 Good colour fastness to light Wash
fastness is poor to moderate
 Easiest to produce, simplest to apply
 Also known as substantive dyes

 Insoluble in water
 Require reduction to apply
 Reduced(hydrosulphite dissolved in alkali - NaOH)^
solubilised applied oxidised
 Incomplete colour range
 Good to excellent light and wash fastness
 Indigo - natural vat dye
 Primarily for cotton

 Insoluble in water, made soluble with the
acid of caustic soda and sodium sulphide
 Application similar to vat dye
 Complete colour range except for red
 Dull colours used mainly for dark colours -
browns, blacks and navy blues

 Used for heavy work clothes
 Black sulphur dye is most widely used black dye
 Stored goods may become tender
 Sensitive to chlorine bleach
 Poor to excellent light and wash fastness
 Poor to good - yellows and browns
 Good to excellent - darker shades

 Used for batiks
 Colour developed on the fabric
 Good to excellent light and wash fastness
 Some sensitive to chlorine and peroxide
bleach
 Bright shades particularly reds violets,
yellows and burgundy
 Primarily for cotton
 Poor fastness to crocking
 Low in cost

 Protein, acrylic, nylon
 Bright colours
 Most are not fats to washing
 Vary from poor to good in fastness to light
and perspiration
 Excellent fastness to dry cleaning
 Dyes applied from acid bath rather than
water bath

 Less bright than acid dyes
 Have better fastness to laundry, perspiration
and light

 Dull colours but excellent fastness to light,
washing, perspiration
 Widely used on wool floor coverings

 Bright shades of excellent fastness to light,
washing, perspiration, crocking on fibers
 Very poor fastness to washing and light on
cellulosic and protein fibers

 Mostly for cellulosic but also used on protein fibers
and nylon
 Bright shades
 Generally good to excellent fastness to light,
washing, perspiration and crocking
 Poor fastness to chlorine
 Difficult dye for colour matching

DISPERSE DYES
 Wash fastness varies with fiber
 Poor on acetate, excellent on polyester
 Fastness to perspiration, crocking and dry cleaning good to
excellent
 Light fastness fair to good
 Gas fading(loss of colour or change in colour on exposure to
nitrous oxide- a pollutant in air) on acetate, especially blues
and violets

These are not true dyes and can be used on all fibers.
 Pigments do not combine with the fiber molecules as
dyes do. They physically hold on to the textile
material with resin binders like glue etc.
 Heavy shades tend to stiffen fabric
 Excellent fastness to light
 Poor fastness to crocking in heavy shades
 Fair to good fastness to hand laundering

 Dyeing can be done during any stage in the
manufacture of a textile. They may be dyed
as fibre, as yarn or as a fabric or as garment;
depending on the type of fabric or garment
being produced.

FIBRE STAGE
DYEING
Stock dyeing Top dyeing
YARN
STAGE
DYEING
Hank /
Skein
Package
dyeing
Beam
dyeing
FABRIC
STAGE
DYEING
Beck/Box/Wi
nch dyeing
Jig
dyeing
Pas
dyeing
Beam
dyeing
PIECE DYEING
Cross & union
dyeing
Resist dyeing:
tie & dye Batik
GARMENT
DYEING
Tie & dye,
Batik and
Ombre effects

 Dyeing of fibers or stock, before it is spun into
yarn. It is done by putting loose, un-spun fibers
into large vats containing the dye solution,
which are then heated to proper temperature.
500 to 3000lbs of fiber can be dyed at one time.
 Features: Most costly method therefore
production is low. It gives excellent dye
penetration and evenness of colour throughout
the fabric. Strong element of fashion risk; a
decision of colour is made at very early stage of
manufacture. Used mostly for woollen materials.
It's advantage being that Different colour fibres
can be spun together to create mixed colors
yarns with ombre' effects.

 Slivers known as top dyed in the stage of
manufacture between fiber and worsted
yarn.
 Results are similar to stock dyeing in terms of
evenness and colour penetration.

It is dyeing of yarn before they are woven or
knitted into fabrics. It is dyed in different
forms- skeins, packages or beams.

 They are loosely wound are immersed in dye
vats which are designed for the purpose.
Knitted yarns are dyed as skeins – most costly
yarn dyeing method.

 Yarn wound on a spool or tube called package.
Many such spools fit into the machine.
 Dye flows from center to outside and then from
outside to inside of the package.
 Package dyed yarns do not certain softness and
loftiness that skein dyed yarns do.
 Widely used method for both knitted and woven
fabrics.

 Much larger version of package dyeing. An
entire warp beam is wound onto to perforated
cylinder which is then placed in the dyeing
machine. Flow of dye bath alternates like
package dyeing. Most economical method of
yarn dyeing.

 Yarn dyeing is less costly than stock or top
therefore processes are more productive
 Permits excellent penetration of dye into the
fiber and thus produces a great clarity of
colour.

 For manufacturer of plaids, stripes, checks
and other multicolour designs

 Yarn dyeing is used as a technique to create Ikat
fabrics.
 Ikat is a method of creating designs in fabric by the
use of resist dyeing. The pattern isn’t created by
painting or printing, but by protecting parts of the
yarn with a resist by binding it before the dyeing
process, removing the resist after dyeing, possibly
repeating this process multiple times, and then using
this yarn in the warp, weft, or both.
 Warp ikat is commonly found, weft ikat less so, and
double or compound ikat the most complicated of all.
It’s slow, laborious work that takes a skilled artisan to
master.

 The dyeing of cloth after it has been woven
or knitted, is known as piece dyeing. It is the
most common method of dyeing use. Various
methods used for this include:
 Beck/Box/Winch dyeing
 Jig dyeing
 Pas dyeing
 Beam dyeing

 oldest type of dyeing method.
 The fabric piece is sewn end to end and is
dyed in a rope like form in relaxed condition.
 Fabric moves on a reel and is kept immersed
in the dye bath except for few yards around
the reel.
 Advantages: it retains softness of hand and
fabric fullness. It is used for light weight
fabrics like knits and also wavy fabrics like
woollens.

 Consists of a stationary dye bath with 2 rolls
above the bath.
 The cloth is carried around the rolls in open
width and is rolled back and forth through
the dye bath once in every 20 minutes or so
and is on rollers the remaining time.
 There are some problems of level dyeing.

 In this, fabric runs through the dye bath in open width and
then between squeeze rollers that force the dye into the
fabric.
 Most pad dyeing part of continuous system or range where
fabric continuously runs between pad and then into other
chambers – steam, washer, rinse, dryer.

 Similar to yarn beam dyeing. Here fabric
beams are used instead of warp beam.
 Used for light weight fabrics, open
constructions since dye bath cannot circulate
through densely constructed fabric.
 Advantages: rapid and economical method
for light weight and open fabrics. No stresses
and tensions like in jig and pad method.
Involves less fashion risk as compared to
other methods.

 Piece dyeing generally produces solid colours
 Tie and dye and Batik are the resist-dyeing
processes for creating attractive coloured
designs on fabrics.
 However, while in Batik, resistance to dye
penetration is provided by a coated layer of wax,
in the case of tie and dye, this is achieved by
knotting, binding, folding or sewing certain parts
of the cloth in such a way that the dye cannot
penetrate into these areas when the cloth is
dyed.

 This is also a hand process in which the colour
penetration is resisted by using tightly tied cotton
threads .
 It is a laborious process producing beautiful results in
a number of colours.
 In tie and dye , the yarn or fabric to be dyed is first
tied with threads to resist colour penetration in areas
as required by the design and then dyed in the first
colour, which is lightest of all.
 This process of tying and dyeing continuous till the
product is coloured in its final colour.

 A method of coloring fabrics made from more
than one kind of fiber, for example, a wool and
cotton blend.
 Each fiber in a fabric designed for cross-dyeing
takes a specific dye in a different color or in
variations of a color.
 A fabric that is crossdyed is more than one color.
 Cross-dyeing is often used to create heather
effects (soft, misty colorings), but strongly
patterned fabrics can also be achieved,
depending on the fibers used in the fabric.

 Example- a shot effect can be created in the
polyester cotton blend, by dyeing polyester
component with red disperse dye and cotton
component with yellow reactive dye. The
produced fabric will give reddish orange
yellowish effect (Heathered effect).

 Union dyeing is “a method of dyeing a fabric
containing two or more types of fibers or
yarns to the same shade so as to achieve the
appearance of a solid colored fabric”.
 Fabrics can be dyed using a single or multiple
step process. Example: fabric of polyester
and cotton can be dyed in solid green by
using disperse dye for polyester and reactive
dye for cotton.

 It is dyeing of completed garments. These
include only non-tailored categories like
sweaters, hosiery and pantyhose.
 Tailored garments like suits and dresses
cannot be dyed as garments because the
differences in shrinkage of the various
components distort and misshape the article.

 Garments are loosely packed in large nylon
net bags. 10 to 50 of such bags are placed in
large tubs containing dye bath and are kept
agitated by a motor driven paddle in the dye
bath. Machine is called paddle dyer.
 It is inexpensive method. t can dye garment
as per buyer orders. It decreases the element
of fashion risk.

 Tie and dye, batik process can be used to
create designs on garments
 Ombré effect created using dip dyeing, color
bleeding, or gradated dyeing technique can
be achieved. It is an effect usually achieved
by hand dipping fabric in dye so that it
gradually goes from light to dark, or
sometimes from one color to another.

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