NATIONAL TEXTILE UNIVERSITY

FACULTY OF ENGINEERING & TECHNOLOGY

Name: Zubair Ahmed Khan

TT-5063
Advance Textile Proessing
Fall 2020
 Lab no. 1
Title:
Dyeing of fabric with direct dye
Introduction:
Direct Dye is a class of dyestuffs that are applied directly to the substrate in a neutral or
alkaline bath. They produce full shades on cotton and linen without mordanting and can also
be applied to rayon, silk, and wool. Direct dyes give bright shades but exhibit poor wash
fastness. Various after treatments are used to improve the wash fastness of direct dyes, and
such dyes are referred to as “after treated direct colours.” Direct Dyes are molecules that
adhere to the fabric molecules without help from other chemicals.
Experimental procedure:
The dyeing of a textile fiber is carried out in a solution, generally aqueous, known as the dye
liquor or dye bath. For true dyeing to have taken place, coloration of fabric and absorption are
important determinants.
1. Set the dye bath with substrate at room temperature.
2. Add dye solution with other auxiliaries and raise the temperature to 90℃
3. Run the bath for 15-20 min and add salt gradually according to the depth of
shade; higher the depth of shade needs more salt concentration
4. It would be better if salt is added to the bath after reaching the temperature to
boiling point. Maximum penetration is achieved during this period.
5. Run the dye bath for 30-50 min at 90-95℃ to complete the cycle.
6. Cool down the bath temperature to 60-70℃
7. Drop the bath and rinse.
The machine used for this purpose is pad thermal dye machine.
Recipe:
Shade = 3.0 %
Wetting agent = 0.2 % Owf
Dirolev-Dlv = 0.3 % Owf
Salt = 15-20 g/l
MLR = 1:10

Results:
After processing of this fabric, the dye levelness was checked that either the dye is evenly
distributed or not.
 Lab no. 2
Title:
Dyeing of a fabric by using vat dyes.
Objective:
• To dye a fabric using vat dye
• To apply resin & softener on dyed piece of that fabric.
Introduction:
A dye is a colored compound, normally used in solution, It is defined as the compound which
containing chromophore and auxochrome groups called dye. Chromophore group is responsible
for dye color due to their saturation. Auxochrome group is responsible for dye fiber reaction. Vat
dyes are made from indigo, anthraquinone and carbazole. They are successfully used on cotton,
linen, rayon, wool, silk, and sometimes nylon. Vat dyes are also used in the continuous piece of
dyeing process sometimes called the pigment application process. The dyeings produced in this
way have high wash and light fastness.
The word vat means vessel. They are water insoluble. They are insoluble in water but become
soluble from by vatting process. The process of converting insoluble vat dye by strong reducing
agent in called vatting process.
Experimental procedure:
• The step in which the reduction of the dyestuff into its leuco-form takes place is called
vatting. It is the process of converting insoluble dye to soluble vat dye. they are reduced
to soluble leuco compound & this process is called vatting.
• A strong reducing agent Na2S2O4.2H2O is used for vatting.
• Absorption of leuco compound by the cotton during dyeing. The vatted dye (leuco form)
is substantive to the cellulose material. Dyeing is carried out at lower temperature by
padding then steam is provided to it for dye penetration.
• To achieve adequate exhaustion an electrolyte is added to the dye liquor & temperature
may be increase from 20-60 C & agitated for 15 min in an opened container for oxidation
process & add hydrogen peroxide and acetic acid.
• Then wash with the cold water & the dry it.
• After this process, three fabric pieces were manufactured. One simple by oxidation
process, 2nd by applying resin and 3rd by applying softeners.
Recipe:
Water = 500ml
Na2S2O4 = 5g
Dye = 10g
Steam time = 4 min
Temp = 102 C
NaOH = 5g/l
For oxidation:
Water = 2.5l
H2O2 =10ml
Acetic acid = 2.5 ml
Results:
After applying resins and softner and simple dyed fabric, the fabric was checked under shade
change instrument & there we saw that the fabric that was just simply dyed have more intense
shade than that of resins and softner.
 Lab no. 3
Title:
Dyeing of polyester fabric using non-ionic dye (disperse dye)
Objective:
• To learn about non-ionic dye & its process on fabric.
Introduction:
Dyes are colored, unsaturated organic chemical compounds capable of giving color to a substrate (a
textile), i.e., coloring or dyeing it. The term “disperse dye” have been applied to the organic
coloring substances which are free from ionizing groups, are of low water solubility and are
suitable for dyeing hydrophobic fibers. Disperse dyes have substantivity for one or more
hydrophobic fibers e.g. cellulose acetate, nylon, polyester, acrylic and other synthetic fibers. The
negative charge on the surface of hydrophobic fibers like polyester cannot be reduced by any
means, so non-ionic dyes like disperse dyes are used which are not influenced by that surface
charge.
Experimental Procedure:
Disperse dyes are not soluble in water. Dispersing agents are used to make them soluble. It
captures the dye molecules from surroundings and disperse it into smaller molecules.
We use two methods for dyeing the polyester fabric:
1. High temperature dyeing methods.
2. By using Carries.
By using high temperature method:
• At first a paste of dye and dispersing agent is prepared, and water is added to it.
• PH is controlled by adding acetic acid.
• This condition is kept for 15 minutes at temperature 60°C.
• Then the dye bath temperature is raised to 130°C and this temperature is maintained for 1
hour. Within this time, dye is diffused in dye bath, adsorbed by the fiber, and thus
required shade is obtained.
• The dye bath is cooled as early as possible after dyeing at 60°C.
• The fabric is hot rinsed and reduction cleaning is done if required.
• Then the fabric is finally rinsed and dried.
By using carriers method:
Carries are used to swell the fibers to make them dyeable, but they are non-friendly to
environment.
• At first, a paste of dye and dispersing agent is prepared and then water is added to it.
 • Dye bath is kept at 60°C temperature and all the chemicals along with the material are
added to it. Then the bath is kept for 15 min without raising the temperature.
• pH of bath is controlled by acetic acid at 4-5.5.
• Now temperature of dye bath is raised to 90°C and at that temperature the bath is kept for
60 min.
• Then temperature is lowered to 60°C and resist and reduction cleaning is done if
required. Reduction cleaning is done only to improve the wash fastness.
• Material is again rinsed well after reduction cleaning and then dried.
Recipe:
Dye, dispersing agent, acetic acid, carriers.
Results:
Using the first method, the dye was not uniformly distributed on fabric surface. On contrast to 1st
method, the carriers used for dyeing gives better results was evenly distributed. Levelled dye was
seen by using 2nd method
 Lab no.4
Title:
Fabric Color Matching Process with Spectrophotometer.
Objective:
To study about the procedure of fabric shade Matching Process with Spectrophotometer.
Abstract:
A spectrophotometer is a special machine that measures the light intensities as a function of
wavelength. In this lab, a Data color 850 is used to analyze the color of a sample. It can quantify
the difference between an achieved color and its original standard. These differences are called
Delta E (error) Values. The delta acceptance levels are 0.5.
Introduction:
A spectrophotometer is a physical tool that is eminently suited to measure the most important
variable of all, the shade and strength of the dyestuffs themselves, whether they be in solution or
on the fiber. Spectrophotometer used by dyeing factory and colorant manufacturers all over the
world. Normally lab managers analyze the color of the swatch with the help of a
spectrophotometer.
Experimental Procedure:
Flow Chart of Color Matching Process with Spectrophotometer:
Calibration the data color 850 instrument.
Click the Calibrate button on the button bar, or Instrument Menu,
Calibrate.
Click Calibrate. The Prepare for Calibration dialog box displays.
Place the black trap over the measurement port and click the Ready
button.
Placed a standard fabric piece in front of scanning light and scan it.
Placed the given fabric piece in front of scanning light and scan it.
Use DL⁕, Da⁕, Db⁕ to match
Ok
Finished

Observations and Calculations:

Conclusion:
The Data color 850 spectrophotometer is color measuring instrument device for measuring,
specifying and evaluating color in both laboratory and production settings, especially where
precise digital color communication is required.