Ashok Athalye, Arindam Chakrabarti and Vikas Shirke - Fibre2fashion

By:
Ashok Athalye,
Arindam Chakrabarti
&
Vikas Shirke

The Art of ‘Dyeing’ – Continuously
By: Ashok Athalye, Arindam Chakrabarti and Vikas Shirke
The Textile Industry, mother of Indian industrialization and the second largest employment generator (about
4.5 Cr people, after Agriculture sector), accounts for about 20 % industrial production. By 2010 this Industry
is expected to grow from INR 150,000 cr. to INR 320,000 cr. This is one of the key drivers for our economy
and any change/development in this sector would highly impact many allied industries and affect socioeconomy
of the country.
Of late this industry is witnessing a paradigm shift in the concepts, applications and processing technologies.
The influencing factors are considered to be the cost pressures, high quality demands, environment
regulations, fashion trends & supply chain logistics. This has brought awareness in terms of need for
technology up gradation, machinery modernization, innovative application techniques, cost optimised
processing and increasing production capacities for achieving economies of scale.
One of the ways to reduce the impact of water consumption, effluent treatment cost, energy requirement and
productivity is by shifting from batch wise processing to the highly productive semi-continuous and
continuous application method.
Cotton is the most widely used natural fiber, due to its physio-chemical properties like feel and comfort of
wear to human body. It is processed either in its natural or regenerated forms like Viscose, Modal & Lyocel,
as self or in blend with synthetics or other innovative, eco friendly fibers like Bamboo, Soya bean, Milk,
Paper, Charcoal, etc. Out of the various classes of dyestuffs used for cotton dyeing - Reactive & Vat dyes
occupy the major share. The highest volume is of Reactive dyes owing to their ease of application, wide
shade gamut, bright shades, all-round fastness properties & cost economies. However, the Vat dyes are still
enjoying a fair share due to their highest level of fastness properties.
The cotton Reactive dyestuff, first developed and launched by ICI – PLC, UK in 1956 as cold brand ‘Procion’
dyes and then manufactured in India in technical collaboration with ATUL, have seen significant changes
and modifications from chemical constituents and application technologies point of view. A brief survey of
the Reactive dye development over the years indicates that the technology has evolved with machinery
usage, simplicity of application, productivity, improvement in reproducible dyeing quality and higher fastness
standards.
The high reactive Cold brand, dichlorotriazine based Procion M dyes developed in 1956
The Hot brand, monochlorotriazin based Procion H- widely used for printing came in 1957
The vinyl sulphones based Remazol commonly used in padding, followed in 1957-58
The high energy, bis monochlorotriazines, Procion HE introduced in 1968
The warm dyeing, hetero bi-functional, Sumifix Supra launched in 1980
The high exhaust, high tinctorial, modified HE dyes as HEXL/XLE in 1986 &
Various multi-functional reactive moieties based on modified Vinyl Sulphone, Triazine, Pyrimidine,
Quinoxaline, etc. evolved after 1980, are generally recommended both for exhaust & continuous
applications.
From processing application point of view the estimated usage of the Reactive dyes is given below. The
continuous and semi-continuous application segment has considerably increased recently and is expected
to grow further as many units are setting up such machineries.

Segment wise application - Reactive Dyes
Printing
20%
Continuous
(PDPS & Pad
Humidifix)
9%
Cold Pad Batch
(CPB)
14%
Hand process
(Cold )
3%
Exhaust (Hot)
9%
Qualitative Comparison - Exhaust / Semi-Continuous / Continuous
Exhaust (Warm)
45%
Sr. Semi-
No. Features Exhaust Continuous Continuous
1 Productivity √ √ √ √ √ √
2 Longer run of fabric √ √ √ √ √ √
3 Reproducibility √ √ √ √ √ √ √ √
4 Cost of labor √ √ √ √ √ √
5 Cost of Water √ √ √ √ √ √ √ √
6 Cost of Steam √ √ √ √ √ √ √
7 Uniformity in dyeing √ √ √ √ √ √
8 Dye hydrolysis √ √ √ √ √ √
9 Penetration of Color √ √ √ √ √ √ √
10 Spot correction √ √ √ √ √ √
11 Machine Cost √ √ √ √ √ √
√ Advantageous
√ √ √
More
Advantageous
Most
Advantageous

Steam
Man Power
Machine
Power
Water
Man Power
Machine
Exhaust Dyeing -
Relative Cost
Scenario
Continuo us
Dyeing - Relative Cost Scenario
Effluent Treatme nt
Steam
Effluent Treatment
Aux. + Chemicals
Dyes
Power Water
Dyes
Aux. + Chemicals

As can be seen from above, the continuous and semi-continuous applications have many advantages
over
the traditional exhaust method of dyeing in terms of productivity and overall processing co st, however,
to
achieve uniformity of dyeing and reproducibility of results, various factors need to be taken in to
consideration and have to be critically monitored.
Cold Pad Batch (CPB) – semi continuous process
The classic CPB dyeing process for Reactive dyes has undergone significant changes since its development during the early sixties. Effective co-ordination between a dyestuff manufacturer, textile processor, and
machinery producer has led to ongoing improvements in creating new high performance dyestuffs and
optimized periphery for padding units.
The major milestones are development of metering pumps, introduction of sodium silicate as a fixing alkali,
improved quick lab dye-fixation method, mathematical determination of pad liquor stability under practical
conditions, development of silicate free alkali systems, etc. In addition to these developments, the research
and development of new reactive dye chromophores and anchor systems have continued to be innovation
targets to provide better pad liquor stability under different climate conditions, length and width wise uniform
level dyeing and optimized compatibility in ternary combinations.
The advantages of CPB dyeing include low energy requirements, low labor intensity, low initial investment,
high fixation yields, easy wash-off, high wet fastness properties, overall cost-effectiveness, excellent
penetration of dyestuffs into the fiber so improved solidity of shades. Standard articles dyed by this method
include piece goods made of cotton, linen, viscose, lyocell and their blends with synthetics, terry towels, pile
fabrics and knitwear. The expertise involved in CPB technology provides the basis for better quality, higher
productivity, higher differentiation and reduced production risk.
Though advantageous, economical and highly recommended process for medium to dark shades, the dyer
usually
encounters some common problems viz tailing, center-selvedge variation, laboratory to bulk and
bulk-to-bulk
reproducibility, non-solidity in shade, patchiness, crease marks, face-back variation, insufficient
removal
of unfixed dye leading to poor fastness properties, etc.
In order to minimize most of these problems arising out of manual, mechanical and process relate d issues
and to achieve trouble free dyeing / RFT performance, the highlights of important check points /
recommendations summarized as follows:
• Pretreated fabric should be checked in terms of following parameters (both lengthwise and
widthwise):
1. Desizing efficiency: Tegewa rating should be >6
2. Absorbency: depending on fabric quality/ construction/ test method varies from instant to 10
seconds
3. Core alkali: fabric core pH should be 6-7
4. Residual Peroxide : Should be nil
5. Whiteness [CIE] : depending on shade depth varies from 60-75
6. Ca/Mg hardness: on fabric should be

• Optimum padding trough volume - trough turn over time should as low as possible to avoid
tailing/variations
• Perfect control / synchronization of major three parameters:
(a) Pick-up, (b) Immersion time and (c) Machine speed
Cold Pad Batch with – TULACTIV C dyes
TULACTIV C Dyes X g/l
Wetting agent (Tulachem Wettex
CDNF)
2 g/l
Caustic Soda As furnished in Table I
Sodium Silicate As furnished in Table I
Liquor temperature 22 0 C – 25 o C
Liquor pick up 60 - 65%
Batching Time 16 Hrs
(Dyes + Aux) solution : (Caustic + Silicate) solution = 4 : 1
TABLE I
Dye Concentration (gpl)

The important points to consider and monitor are
(a) Pick-up
Pad pressure
Pad speed
Immersion time
Dye bath chemicals nature
Fabric
quality & construction
Following points are important:
Pick up must be within spe cification (Wov en: 60-80%, Knitted: 80-100%)
Uniform across the width to avoid centre- selvedge variation
Uniform throughout batch and from b atch to bat ch
(b) Immersion time
Pad speed
Distance from dip to nip
Following points are important:
Should be 1-2 seconds (measured from the time the fabric enters the bath until squeezed
between nip rolls)
The level of liquor in the pad trough must b e constant throughout the run to maintain the
same immersion time
(c) Machine speed
Wetting out time & fabric appearance
Required immersion time & trough turnover
time
Following point
is important:
Speed must be constant (30-45 meters / min.)
No intermit ant stoppages
• Machine speed during padding should be adjusted
in such a way, so that effective replenishment of
padding trough takes place (depends on GL M of fabric, trough volume) Speed
fluctuation is not
desirable.
• Foaming in colour preparation tank / silicate tank / ducts / padding trough should be as low as
possible ( affects trough level)
• Chilling jacket arrangement in colour tank is desirable to
keep consistent temperature throughout the
entire padding process.
• The temperature influencing factors are temperature of the incoming fabric, temperature of process
water, temperature of cooling water, ambient temperature, exothermal reaction, pad-liquor
temperature and temperature of the padding mangle.
• Chilling jacket arrangement in Silicate / Caustic tank is desirable
• Chilling jacket arrangement in padding trough is desirable throughout the entire padding process

• The cut off valves at the bottom of colour preparation tank & silicate tank should be at proper
positions (just touching the bottom of tanks, to avoid presence of undesirable water column before
actual liquor column)
• If the process water pH is greater than 7.0, then appropriate amount of acid should be added in tank
containing dyestuff solution to maintain pH 6.0 – 6.5. This will prevent any premature hydrolysis of
dyestuffs
• Padding liquor temperature should be 20-22 o C (should remain uniform throughout the padding
process)
• pH of pad liquor solution should remain constant throughout the entire padding process
• The ratio of color solution: alkali solution = 4:1 should be maintained constantly throughout the
padding process
• The quality of the supplied Sodium Silicate (strength-°Be/°Tw, Na2O: SiO2 ratio) / Strength- °Be/°Tw
of Caustic Soda / purity of Soda ash should be checked.
• Usage of correct alkali system is very important from the point of view of good diffusion e.g. for
dyeing tightly woven material and terry towels, ‘Soft alkali system (Soda ash / Caustic
soda system)’
controls the rate of fixation and allows the diffusion of dyestuffs into the cellulose structure.
• Before CPB padding, RFD fabric should be properly conditioned (should pass over a chilling roller
before padding / take more amount of fabric on scray before padding for natural cooling).
• Soft brushing unit may be installed for removing
loose fluffs / yarn residues present on fabric before
padding.
• Before starting
padding, padding trough should be filled with padding liquor and drained and refilled,
this is required for stabilization
of bath.
• At least 20-30 meters of leader
cloth should be attached both end of RFD fabric. This is required for
stabilization of padding liquor.
The starting end of actual RFD fabric should enter the padding trough
with a specific speed. Also the end of RFD fabric should leave the padding trough with the same
con stant speed. This will avoid shade variation of initial portion & end portion of padded fabric with
the rest portion.
• Cleaner
leader cloth should be different than RFD fabric.
• During entire process of padding, care should be taken, so that there is no chocking
of color /
silic ate line.
• Care should be taken to ensure even feeding of dye liquor across
width of pad trough
• Usage of reduction inhibitor
in pad liquor is useful.
• After padding, the batch
should be immediately and properly covered with polythene sheet
• Continuous and uniform rotation of
padded fabric during batching stage should be ensured
• The batch should be kept away from
steam, water spray or, acid fumes
• Recommended Wash-off sequence should be followed to achieve desired fastness properties
TULACTIV
These economical compact reactive dye ranges are developed for dyeing of cotton woven, regenerated
cellulose fabrics and open knit goods by semi-Continuous (Cold Pad Batch) and Continuous (Pad-Dry-Pad-
Steam / Pad-Steam / Pad-Humidity Fix) as well as by Exhaust.
Known for excellent reproducibility, high productivity, shade continuity
over longer lengths, fastness levels
and all round application
performance.
The special features and associated benefits are as follows:
• Excellent compatibility / outstanding bath stability: Shade continuity over longer lengths.
• High degree of fixation / Easy wash-off: Meets stringent wet fastness requirements.
• Low recipe cost / Less water and energy consumption (CPB): Cost effectiveness.
• Robust system / Lab to bulk reproducibility: Achievement of RFT results.
• High tinctorial
strength / Build-up: Economical medium / dark shades.
#
C / CC
Golden Yellow C-R Trichromatic
golden yellow component with outstanding build-up,
Conc. excellent light / overall fastness properties and dischargeability.
Rubine C-B
Red C-6BF
Trichromatic red component with excellent fastness and wash-off
properties.
Red component for pale
fastness.
/ light trichromatic shades with highest light

#
Maroon C-D
Brill. Blue C-B
Strongest economical dischargeable deep red for dyeing medium to
deep combination shades with good light, chlorine and other fastness
properties.
Trichromatic blue component for light to medium shades with excellent
light / overall fastness properties and dischargeability.
Royal Blue C-R Basis for royal blue, green and violet shades.
Turquoise C-G
# Navy C-GB
Basis for brilliant turquoise and green shades.
Batching time should be 24 hours.
Trichromatic navy component for medium to dark shades with
excellent overall fastness properties and dischargeability.
Navy C-BL Basis for economical combination navy and black shades.
Black C-GR Basis for economical black shades.
Black C-2N
Deep Black C-HS
Component for dyeing deep black shades with good wet fastness
properties.
Component for achieving highest possible deep jade black shades
with excellent wet fastness properties.
Standard trichromatic combination for high light fast pale shades
Standard trichromatic combination for light to medium shades.
# Standard Trichromatic combination for medium to dark shades.
Reactive dyes - Comparison: Exhaust (Jigger) / Semi-Continuous (CPB) / Continuous (PDPS)
Note: Considered
only Dyeing & after treatment parts
Fabric
Type of fabric Mercerized bleached 100% Cotton Twill fabric
Total batch
size (meters) 10,000
GLM o f fabric 250
Total batch
weight (kgs)
CPB
2500
Capacity (meters) 2500 i.e. 625 Kgs. / batch
(Dye + Auxiliary) solution (Silicate+ Caustic) solution = 4:1
Total liquor requirement (liters) 415 (for each batch)
For dyeing 10,000 meters of fabric 4 lots to be taken on CPB
Expression (%) 60
Speed of Padding machine (meters/min.) 35
Trough capacity (liters) 40
Batchin g time (hours)
16
Speed of Soaper (meters/minute)
PDPS
50
Expression (%) 60
Dye padding trough capacity (liters) 30
Total dye
padding liquor to be prepared for 10,000 meter
fabrics (liters)
1530
Speed of Pad-Dry machine (meter/min.) 40
Chemical padding expression (%)
80
Chemical padding trough capacity (liters) 50
Total che mical padding liquor to be prepared
for 10,000
meter fabric (liters)
2050
Spee d of Pad-Steam machine (meters/min.)
60

Reactive dyes - Comparison: Exhaust
(Jigger) / Semi-Continuous (CPB) / Continuous (PDPS)
Note: Considered Dyeing & after treatment parts only (Pretreatment & Finishing parts are not considered)
Factor
Do Quant
sag ity
e requir
(% ed
/g/l kgs/
) 1000
meter
s
Exhaust Pro cess (Jigger)
LR= 1:4
Quanti
Quant Pric Amoun Amo Amount Co
ty ity e t unt [INR/kg] st
require
requir [INR [INR/kg [INR/ For [IN
d kgs/ ed /kg] ] kg] 10000 R/k
2500
kgs/ meters
g]
meters
10000
meter
s
Reactive Yellow 1.50 3.75 382.00 1432.5 14325.0
0
0
Reactive Red 0.42 1.05 401.00 421.05 4210.50
Reactive Na vy 1 .20 3.00
446.00 1338.0 13380.0
0 0
Total Dye Cost 31915.5
0
Tulachem Texcell
DSA
1.00 1.00 137.00 137.00 1370.00
Common Salt 60.00 60.00 3.00 180.00 1800.00
Soda ash 5.00 5.00 15.00 75.00 750.00
Caustic Soda
(flakes)
1.00 1.00 22.00 22.00 220.00
Acetic acid 2.00 2.00 38.00 76.00 760.00
Tulachem Texwash
DET
2 .00 2.00 118.00 236.00 2360.00
Tulachem
Demin
AAS
0.30 0.30 38.00 11.40 114.00
Total
cost
(Auxiliary
+Chemical)
7374.00
Semi-Continuous Process (CPB)
Re active Yellow 25.0 10.375 382.00 3963.2 15853.
5 00
Reactive Red 7.00 2.905 401.00 1164.9 4659.6
1 4
Reactive Navy 20. 00 8.300 446.00 3701.8 14807.
0 20
To tal Dye Cost
35319.
84
Tulachem Wettex
CDNF
2 .00 0.830 226.00 187.58 750.32
Caustic Soda flakes 2.70 1.1 21 22.00 26.62 106.48
Sodium
silicate 85.00 35.275 10.00
352.75 1411.0
(60°Tw)
0
Tulachem
Demin
AAS
2.00 6.250
38.00 237.50 950.00
Tulachem
Texwash 1.00 3.125
118.00 368.75 1475.0
DET
0
Tulachem
Demin
AAS
0.50 1.562 38.0 0 59.35 237.40
Total
cost
4930.2
(Auxiliary
+Chemical)
0
12.76
2.94
15.71
14.12
1.97
16.10
Cost
[INR/
mete
r]
3.1
9
0.7
3
3.9
2
3.5
3
0.4
9
4.0
2
Time
(mins
.) /
Mt. of
fabric
0.51
(excl
uding
dryin
g)
0.15
(excl
uding
dryin
g)

Continuous Process (Pad - Dry - Chemical Pad - Steam)
Reactive Yellow 25.00 38.25 382.00 14611.5
0 0
Reactive Red 7.0 0 10.71
0
40 1.00
4294.71
Reactive Navy 20.0 0 30.60
446.0 0
13647.6
0
0
Total Dye Cost 32553.8
1
Tulachem Resist
Salt
2.00 3.060
90.00 275.40
Tulachem Wettex
CDNF
2.00
3.060 226.00 691.56
Tulachem Antimig 10.00 15.30 150.00 2295.00
PD
0
Tulachem Resist 5.00 10.25
90.00 922.50
Salt
0
Common Salt 250.0 512.5 3.00 1536.00
0 0
Soda ash 20.00
41.00
0
15.00 615.00
Caustic Soda
(flakes)
2.50 5.125 22.00 112.75
Tulachem Demin 2.00 25.00
38.00 950.00
AAS
0
Tulachem Texwash 2.00 25.00
118.00 2950.00
DET
0
Tulachem Demin 0.20 02.50
38.00 95.00
AAS
0
Total Cost
10442.4
(Auxiliary
+Chemical)
6
13.02
4.17
17.19
3.2
5
1.0
4
4.2
9
0.042
(inclu
ding
dryin
g)

Continuous process: Pad-Dry-Chemical Pad-Steam
(PDPS)
The reasons for opting continuous dyeing include enhanced
productivity, better process control leadin g to
better reproducibility and production flexibility.
Segment wise a pplication - Vat Dyes
Yarn
(convention al)
22%
Continuous
(PDPS
)
15%
Printing
3%
Jigger ( pad-Jig)
25%
Yarn (package)
35%
The continuous dyeing is a two-stage operation, which involves continuous preparation
and continuous
dye application
& fixation. It is estimated that about 70% of dyeing faults generally occur due to faulty
preparation
of fabric. So, Continuous preparation plays an important role to achieve faultless dyeing. The
integrated preparation consists of the Desizing, Scouring and Bleaching operations. This is followed by
Mercerization treatment to improve dye uptake, dimensional stability and luster of fabric.
The common problems, which are experienced in shop-floor are formation of color specks, tailing, faceback
variation, centre-selvedge variation, improper laboratory to bulk and bulk to bulk reproducibility, nonsolidity
in shade, crease marks, etc. In order to achieve trouble free dyeing / RFT, the important check
points / recommendations for above application steps may be summarized as follows:
PDPS Dyeing with Vat Dyes – NOVATIC Micro Disperse
Process: Pad – Dry – Chemical Pad – Steam
STEP 1. Dye Padding: NOVATIC M/D dyes : X g/l
Tulachem Texflow LDP : 2 g/l (Dispersant)
Tulachem Wettex CDNF : 2 g/l (Anionic Wetter)

Tulachem Antimig PD : 10 g/l (Anti-migrating agent)
Liquor Temperature : 30° C
Liquor Pick – up : 60 -65 %
STEP 2. Drying: IR (Infra Red) Drier Hot Flue Drier (Lab: Temp. 110°C, Time-1 min.)
STEP 3. Chemical Padding: Caustic Soda (Flakes) As recommended in Table 1
Hydros As recommended in Table 1
Tulachem Texflow LDP : 2 g/l
Liquor Temperature : 30°C
Liquor Pick – up : 65%
STEP 4. Steaming: Temperature : 100±1°C
Time : 60secs.
STEP 5. After Treatment Sequence:
Cold Rinse Oxidation (60°C)
(Hydrogen Peroxide –4 ml/ l)
Table 1: Concentrations of Caustic Soda and Hydros during Chemical Padding
Concentration of dyestuffs
Chemical bath concentration (Expression 67%)
(g/l) Caustic soda flakes (g/l) Sodium Hydrosulphite (g/l)
0-5 25 28
5.1-15 28 31
15.1-20 30 33
20.1-30 35 39
30.1-40 42 47
40.1-50 50 56
50.1-60 56 60
60.1-70 62 68
70.1-80 70 76
NOTE: - The above concentrations can be treated as a guide. However, adjustments may need to be made
locally to adapt to particular working conditions and machines.
Dye Padding:
Dry
Cold Rinse
• Proper selection of dyes in mixture, keeping in view of compatibility factors.
• Preparation of dye padding liquor following recommended method. During preparation of dye
padding dispersion, at all stages, filtration steps are very important.
• Addition of appropriate quantities of wetting and antimigrating agents depending on fabric
construction and GLM of fabric. Wetting agent helps to increase penetration of dyestuff. Anti
migrating agent helps to control migration of dyestuff (Vertical & horizontal
migration).
• Optimum trough volume is desirable.
• The wetting agent must not foam and must not cause any aggregation or precipitation of the dyes
during the life of the pad liquors
• The dye padding liquor must show no tendency to either settle or aggregate
• The desirable temperature of dye padding liquor is 25 o C
• Dye padding expression – Simulation of bulk and laboratory is important
• No LMR pressure variation during padding is desirable
• Least foaming in dye padding liquor is expected
Soaping at 95 o C
(Tulachem Texwash
DET 1g/l)
Neutralisation
(Tulachem
Demin AAS
1.0g/l at 40°C)
Soaping at 95 o C
Hot Wash
(80°C)

• Regular checking of dye padding rollers for any surface damage is necessary
(a) Drying:
• Proper airing zone before IR assembly.
• Depending of quality of fabric and working condition, the IR efficiency is set in such a way so that
fabric enters into the hot flue zone with around 30% residual moisture.
• Condition of all burners in IR zone needs to be inspected frequently.
• Effective air circulation in hot flue drier to avoid face / back variation.
• Gradual increase in temperature should be maintained in successive
chambers of hot flue zone.
• The fabric should be uniformly dried to desired moisture content
while emerging from hot flue
assembly and batch ed on roller avoiding crease marks.
(b)
In case of Vat dyeing, the chemical pad liquor is a strong alkaline reducing
solution, which reduces
inso luble Vat dye into the Vat leuco form in the subsequent steaming process. The amount of caustic
soda and sodium hydrosulphite has to be
calculated as per the depth of shade and pick-up (i.e.
percentage expression of chemical pad liquor). Less reducing agent would
result in low dye fixation,
poor build-up and poor reproducibility. Excess reducing agent would
increase
the demand on
the
subsequent oxidizing treatment and increase chemical cost and
risk of poor reproducibility.
• Proper cooling and conditioning of fabric before chemical pa
• Optimum trough vol
• Desired mangle expression and no LMR pressure varia
• Constant chemical bath temperature (20 –22 o dding
ume
tion
C) should be maintained
using chilling jacket
arrangement. In case of vat dyeing, formation of leuco form in the chemical
liquor could be avoided
by this process
• Addition of insufficient electrolyte should be avoided to prevent bleeding of dyestuffs (Reactive
dyeing).
• The presence of actual amount of caustic soda and sodium hydrosulphite in chemical bath should
be frequently checked by titration method
(Vat dyeing)
• Use of
reduction inhibitor in pad liquor is recommended especially
for viscose fabric (Reactive
dyeing)
• Addition of glucose
/ sodium nitrite is recommended for Vat dyes, which are sensitive to over
reduction.
• Leas t foaming in chemical bath is desirable.
• In case of Vat dyes, suitable dispersing agent may be added in chemical bath. It helps to maintain
the insoluble Vat dye in the form of fine particles and
prevent aggregation of leuco compounds
• Absence of iron in chemical bath should be ensured. Suitable sequestering agent may be added
(c) Steaming:
and fixation
• Saturated
air-free steam should be used
• Presence
of air in steamer should be strictly prevented to avoid premature oxidation of vat dyestuff.
• Condensation droplets on fabric can be avoided by having an adequate / consistent
steam supply
(d)
Chemical Padding:
• Correct temperature (101 - 102 o C) and dwell time (45-60 seconds) should be maintained. Longer
steaming time causes decomposition of some Vat dyes, and shorter time gives incomplete reduction
o
and heating the ceiling at 106 C.
• At the exit point from steamer, vat dyestuff should be in reduced condition.
• Condition of water seal should be occasionally checked.
0-60 o Oxidation (Vat dyeing):
Oxidation is achieved in a continuous washer by treatment with Hydrogen peroxide at 5 C
• pH 9-10 should be maintained
• Presence of appropriate amount of hydrogen peroxide needs to be checked by
titration method

(e) Wash –off / Soaping:
• Thorough
soaping is desirable to develop true and final shade (Vat dyes). Recommended wash-off
sequence should be followed to achieve desired
fastness properties (Reactive dyeing).
• Checking of temperature, pH, water hardness, time, liquor flow etc. are important.
Considering various parameters of processing, given below is a comparative analysis
Vat dyes - Comparison: Exhaust (Jigger) / Semi-Continuous (Pad-Jig) / Continuous (PDPS)
Note: Considered only Dyeing & after treatment parts
Fabric
Type of fabric Mercerized bleached 100% Cotton Twill fabric
Total batch size (meters) 10,000
GLM of fabric 250
Total batch weight (kgs) 2500
Jigger
Capacity (meters) 1000 i.e. 250 Kg/ batch
Liq uor ratio
1:4
Total liquor
(liters) 1000
Dyein g 10,000 Mts. of fabric 10 lots
Total number of ends in Jigger for each lot
(Dyeing + after treatment) each end - 15 minutes
Pad-Jig
30
Spe ed of Padding machine ( meters/minute)
PDPS
35
Expression (%) 60
Dye padding trough capacity (liters) 30
Total dye padding
liquor to be prepared for 10,000
meters
1530
Speed of Pad-Dry machine (meters/minutes)
40
Chemical padding trough capacity (liters) 50
Chemical pad expression (%) 80
Chemical padding liquor to be prepared for 10,000
meters
2050
Spe ed of Pad-Steam machine
80

Vat dyes - Comparison: Exhaust
(Jigger) / Semi-Continuous (Pad-Jig) / Continuous (PDPS)
Note: Considered Dyeing & after treatment parts only. Pretreatment & Finishing parts are
not considered
Factor
Dosa
ge
[% /
g/l]
Quant
ity
(kgs.)
250
kg
fabric
Quanti
ty
(kgs)
2500
kg of
fabric
Price
[INR/kg
]
Amoun
t
INR/25
0 kgs
fabric)
Amo
unt
INR/
2500
Kg.,
Cost
Time
Cost
[INR/ (mins.)
[INR/
mete / Mt. of
kg]
r] fabric
Exhaust Process (Jigger)
Novatic Yellow M/D 0.192 0.48
2694.0
0
1293.
12
12931.
20
Novatic Brown M/D 0.174 0.43
1875.0
0
815.6
3
8156.3
0
Novatic Olive M/D 0.306 0.76
1563.0
0
1195.
70
11957.
00
Total Dye Cost
33044.
50
Tulachem Texflow
LDP
1.00 1.00 149.00
149.0
0
1490.0
0
Levelling agent 0.50 0.50 120.00 60. 00 600.00
Tulachem
Sequastab EP
1.00 1.00 137.00
137.0
0
1370.0
0
Caustic Soda
(flakes)
12.00 12.00 22.00
264.0
0
2640.0
0
Sodium
hydrosulphite
12.00 12.00 70.00
840.0
0
8400.0
0
Common Salt 10.00 10.00 3.00 30.00 300.00
Hydrogen Peroxide
Tulachem Demin
3.00 3.00 40.00
120.0
0
1200.0
0
AAS (Oxidation
bath)
1.00 1.00 38.00 38.00 380.00
Tulachem Texwash
DET
1.00 1.00
118.00
118.0
0
1180.0
0 13.21
Tulachem Demin
AAS
0.25 0.25 38.00 9.50
95.00
7.06
20.27
Total cost
0.45
(Auxiliary
17655. 3.30 (exclud
+Chemical)
00
1.76 ing
Semi-Continuous Process (Pad-Jig)
5.06 drying)
Novatic Yellow M/D 3.20 4.896 2694.0
0
13189.
82
Novatic Brown M/D 2.90 4.437 1875.0
0
8319.3
8
Novatic Olive M/D 5.10 7.803 1563.0
13.48
7.33
3.37
1.83
0.48
(exclud
20.81 5.20 ing
drying)
0
12196.
09
Total Dye Cost
33705.
29
Tulachem Wettex
CDNF
2.00 3.060 226.00 691.56
Tulachem Texflow
LDP
1.00 1.00 149.00
149.0
0
1490.0
0
Levelling agent 0.50 0.50 120.00 60.00 600.00
Tulachem
Sequastab EP
1.00 1.00 137.00
137.0
0
1370.0
0
Caustic Soda
(flakes)
12.00 12.00 22.00
264.0
0
2640.0
0

Sodium
hydrosulphite
12.00 12.00 70.00
840.0
0
8400.0
0
Common Salt 10.00 10.00 3.00 30.00 300.00
Hydrogen Peroxide
Tulachem Demin
3.00 3.00
40.00
120.0
0
1200.0
0
AAS (Oxidation
bath)
1. 00 1.00 38.00 38.00 380.00
Tulachem Texwash
DET
1.00 1.00
118.00
118.0
0
1180.0
0
Tulachem Demin
AAS
0.25 0.25 38.00 9.50 95.00
Total Cost
(Auxiliary
+Chemical)
18343.
56
Continuous Process (Pad - Dry - Chemical Pad - Steam) Novatic Yellow M/D 3.20 4.89
2694.0
0
13189.
82
Novatic Brown M/D 2.90 4.43
1875.0
0
8319.3
8
Novatic Olive M/D 5.10 7.80
1563.0
0
12196.
09
Total Dye Cost
33705.
29
Tulachem Texflow
LDP
2.00 3.06 149.00 455.94
Tulachem Wettex
CDNF
2.00 3.06 226.00 691.56
Tulachem Antimig
PD
10.00 15.30 150.0 0
2295.0
0
Caustic Soda
(flakes)
28.00 57.40 22.00
1262.8
0
Sodium
Hydrosulphite
31.00 63.55 70.00
4448.5
0
Tulachem Texflow
LDP
2.00 4.100 149.00 610.90
Hydrogen Peroxide 5.00 62.50 40.00
2500.0
0
Tulachem Texwash
DET
2.00 25.00 118.00
2950.0
0
Tulachem Demin
AAS
Total
2.00 25.00 38.00 950.00
(Auxiliary
16163.
+Chemical)
39
13.48
6.46
19.94
3.37
1.61
4.98
0.042
(includi
ng
drying)
Market trends have been influential in developi ng new dyestuff ranges to meet modern customer’s
demands. Retailers / Bran ds are also introducing screening
tests into their performance specifications to
ensure buying of appropriate products. At Atul, we strive
continuously to fulfill
the ever - changing needs of
our customers and have introduced new Ranges (for application
by CPB / PDPS methods) for our
cust omer’s benefit. The special features of those ranges are as follows:
In case of Vat dyes, Atul
ltd. one of the very few global Vat dye manufacturers, produces wide range of
dyestuffs suitable for all methods of applications.

NOVATIC Micro Disperse
(M/D)
Atul Ltd. has developed this compact rang e of Vat dyes for trouble fre e dyeing operation of cellulosic fabrics
and its blends by exhaust as well as by continuous dyeing
m ethod.
Superior
fastness properties, viz. light,
weathering, chlorine, laundering, bleaching, etc. c ater the requirements of work-wear, military wear, home
upholstery, medical clothes,
etc.
The special
features and associated benefits are as follows:
Yellow 5GF
Yellow 4GL
• Uniform, level dyeing of cellulose fabrics an d blends by continuous
dyeing method.
• Super fine, micro-molecular
particle size to ensure stable dye
dispersion, ease of reduction
and speck free performance.
• Ready to use, easy to handle, non-dusting, non-foaming and non mal-odorous dyestuffs.
• Excellent reprodu cibility and shade continuity
over longer lengths.
• Highly
recommended to achieve and meet stringent quality / all round fastness demands.
Bright gre enish ye llow with h igh light and wet
fastness properties.
No catalytic fading of green / blue dyes.
Recomm ended oxidation pH:
7-8.
Greenish yellow component, which is widely used as a shading dye for
military uniforms.
Causes catalytic fading of Jade Green XBN when
yellow to green ratio
(7.5:1) is exceede d.
Yellow 3R Finds widespread use in khaki and olive shades.
Brill. Red 3B
Blue CLF
Brown L
Brown BR
Brown R
Ideal shading dye for combination
shades with
good levelness and all
round
fas tness properties.
Addition of salt is a dvisable to avoid b leeding during chemical padding.
Excellent shading component for continuou s dyeing.
Least sensitive to p rocess variables.
Excellent
basis for beige,
khaki & brown
shades with superior
performance
in continuous
dyeing.
Basis for dark brown & tan shades with suitability
for bleach fast
styles, laundered goods, furnishing and all weather
qualities.
Reddish brown component. Add sodium nitrite (2-3 gpl), to the chemical pad-liquor, if long
steamin g time (60- 90 secon ds) is used.
Jade Green XBN Classic green dye for all fa st outlets.
Olive TN
Grey 6708
Basis for olive shades, with high
properties.
light and all round fastness
Classic grey with excellent performance in continuous dyeing.
Blue CLF A high chlorine fast bright blue for uniform level dyeing.
Navy DS A basic dark navy component.
Direct Black AC
Standard vat black with high light, bleach and wash fastness
properties.
TULACON C - Modified liquid Vat dyes for ‘One Step’ dyeing
These dyes are specially formulated liquid dyes with outstanding wet fastness properties for application on
cellulosic fabrics and polyester / cellulosic blended fabrics by simple, economical, environment friendly
continuous (Pad – Dry – Cure) process. These specialty colors are highly suitable for pastel shades with

high light and chlorine fastness properties. These dyes are padded on fabric with multifunctional auxiliary
system,
dried and fixed by curing method.
The special features and associated benefits are as follows:
• One step, simple and economical process with high productivity.
• High degree of fixation, short fixation time, low water
and energy requirements.
• Applicable on both100% cellulosic fabric and polyester
/ cellulose blended fabric.
• Excellent
laboratory to bulk and bulk to bulk reproducibility.
• No wash treatment, and no salt, alkali in the waste water.
• Minima l use of machinery, no steamer or washer is required.
• Requirement of critical fastness properties,
viz. light, chlorine, etc. are achieved.
Method: Pa d – Dry – Cure (PDC)
STEP 1. Dye Padding: TULACON C : X gpl
Tulachem ATB : 10-15 g/l
Tulachem ATS : 4-5 g/l
Glauber’s Salt : 5 g/l (predissolved)
Tulachem Sequestab EP : 1 g/l
Acetic Acid (30%) : 1.0 ml/l (pH 6-6.5)
Liquor Temperature : 25°C
Liquor pick – up: : 60-65 %
ying: IR (Infra Red) C -140 o STEP 2. Dr Drier (70%) Hot flue drier (120 C)
o
STEP 3. Cu ring: Temp . 170°C, Time- 45 seconds [for 100% Cotton]
Temp.
190°C, Time- 45 seconds [for P/C blend]
Important points:
• Pretreated RFD fabric should be checked in terms of following parameters (both lengthwise and
widthwise): Desizing efficiency (Tegewa scale rating),
Absorbency, Core pH, Residual
Peroxide,
Whiteness Index.
Uniform
behaviour is very important.
• TULACON
C dyes should
be stirred very well before application (both at laboratory & bulk).
• Following steps are needed to be followed for preparation of
padding liquor (in bulk) using
TULACON C dyes:
Colour kitchen:
• Shake & Stir TULACON C dyes (in drum)
thoroughly.
• uired amount
• Feed TULACON dyes steadily into the vortex created by a high-speed stirrer running in water (25 o Weigh req of TULACON C dyes.
Co
30 C).
• Stir for 10-15
minutes.
• Filter twice.
Yellow C-G
Product Overview
Greenish yellow
component.
Moderate light fastness.
Golden Yellow C-R Reddish yellow component.
Pink C-R Good shading component

Red C-B Standard shading red component.
Blue C-R Bright blue component
Green C-B Green component
Brown C-R Basis for khaki, beige, cream shades
Olive C-G Basis for olive shades
Grey C-M Homogeneous grey component.
Correctly controlled continuous dyeing processes are very
effective methods
for producing consistently dyed
quality fabric. Perfect maintenance of equipmen t and close monitoring on
critical
check points are essential
steps for successful ope ration. The key issues that concern dye house management
today have been
identified as cost reduction, improved quality, reduced time of delivery,
perfect repeatability,
reliable results
and maximum machine flexibility.
About the Authors:
The authors are associated with Atul Ltd (Colors Divi sion),
Gujarat.