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Reactive dyeing method - DCT

Methods of Dyeing cotton with Various Reactive dye brands: 

Application on cotton fabric by various dyes- 

Among these five, below is the explanation of the first method.

Explanations -

(1) Cold brand reactive dyes:

Dyeing with salt followed by alkali which is followed by after treatment
The application of reactive dyes involves the following steps -

(i) Dyeing in the presence of sodium chloride (NaCl) to effect as much exhaustion of the bath as possible.
(ii) Chemically reacting the dye with the fibre in the presence of an alkali eg. Sodium carbonate (Na2CO3), trisodium phosphate (Na3PO4), caustic soda (NaOH) etc.
(iii) After treatment of the reactive dyed cotton material (Soaping, washing etc).


Chemical reactions in dyeing : 

Cold brand reactive dyes

D - Dye
R - Reactive (functional) groups

Dyeing procedure :

(i) Preparation of cotton for dyeing (RFD):
Bleached material prepared for dyeing must be free from Alkali. Where necessary, treat it in an exceeding liquor containing 0.5 to 1.0 a part of carboxylic acid (30%) per 1000 parts of water before adding a dye solution. 

This prevents premature localised fixation and improves levelling of the dyes.

(ii) Preparation of dye solution:
The M brand dye powder is pasted with cold water and dissolved by adding water at 50°C. The required quantity of water is then added with stirring to dissolve the dyestuff.

(iii) Dyeing:
Adjust the dye bath pH to six.5 to 7.0 with carboxylic acid and using the acceptable liquor ratio work the fabric for 10 minutes at temperature. After a quarter-hour add pre-dissolved common salt or salt and dye for one more half-hour Add pre-dissolved alkali (soda ash) and continue dyeing for an additional half-hour and so drain the dye bath. As stated earlier the salt and alkali are also added in two portions
The quantities of salt and sodium carbonate for various liquor ratios are given below in table- 

Depth of shade


Soda ash and MLR





Up to 0.5%

30 gpl

5 gpl

5 gpl

3 gpl

2 gpl

0.5 to 2 %

40 gpl

10 gpl

5 gpl

4 gpl

2 gpl

2 to 4 %

50 gpl

15 gpl

10 gpl

8 gpl

4 gpl

Above 4.0%

60 gpl

20 gpl

10 gpl

10 gpl

5 gpl

(iv) Washing off:
After dying, wash the fabric well for optimal fastness. Ten minutes are spent washing the fabric in cold running water. 

(v) After treatment:
(a) Wash the dyed material freed from soap first with plight, then with cold water, and so treat it with 1 to 2 GPL of neutral soap at the boil for a quarter-hour.
(b) After treating the soaping material for 10 minutes with 1 to 1.5 GPL of softening agents, dry it.

This final step is optional and is a wrap-up ( A dye-fixing agent is also applied before this step, if necessary) Figures depict the dyeing cycle and also the process flow sheet.

Dyeing cycle for reactive M brand
Dyeing cycle for reactive M brand 

Sequence - 

Scoured or Bleached yarn 


Enter goods in blank bath 


Add dissolved dye & dye for 15 minutes 


Add dissolved common salt in 2 portions to dye Bath and dye for 10 minutes each 

Add dissolved soda ash in 2 portions to dye 

Bath and dye For 15 minutes each 


Dyeing continues for 20 to 30 minutes 


Squeeze and wash 


Soap at the boil and wash 


Softening or dye-fixing treatment (if required) 


Squeeze and dry 


Questions -

Which methods are used for the reactive dyeing process?

Describe the Cold brand reactive dyes (DCT) method.

What is the dyeing process for DCT reactive dyes?

Which sequence does the DCT Reactive dyeing process follow?


Ahmed, S. (2014, September 29). Reactive dyes - classification. TextileTuts.

Chakraborty, J. N. (2010). Waste-water problem in textile industry. In Fundamentals and Practices in Colouration of Textiles (pp. 381–408). Elsevier.

Clark, M. (2011). Handbook of textile and industrial dyeing: Principles, processes and types of dyes (Matthew Clark, Ed.). Woodhead Publishing.

No title. (n.d.). from

Patwary, E. M. Z. (2012, February 18). Reactive dyes. Textile Fashion Study; Engr. Mohammad Zillane Patwary.

Sayed, A. (n.d.). Why reactive dye is so called? from

What are Reactive Dyes? Types of Reactive Dyes. (n.d.). from

Continue reading,


 - Rushikesh Patil (Textile Engineer)
(DKTE Society textile engineering college Ichalkaranji)
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