Classification of Sulphur Dyes

Classification of Sulphur Dyes:
Sulphur dyes may be classified in many ways:- But according to their solubility there are essentially 3 classes of Sulphur dyes as below:-
  1. Conventional or Water insoluble dyes
  2. Leuco Sulphur dyes (Partially soluble) and
  3. Solubilised Sulphur dyes. 
Sulphur dyes
Fig: Sulphur dyes
These in turn are subdivided in to 6 sub classes, depending on the method of application. Namely–
  1. Method-i 
  2. Method-ii 
  3. Method-iii 
  4. Method-iv 
  5. Method-v 
  6. Method-vi 
1. Method-i:
Conventional Sulphur dyes (i.e. water insoluble Sulphur dyes) are dyed in method i. They have slight affinity to textile fibres of cellulosic origin. Method is as below:-

  • Dye pasted with cold water 
  • Add required amount of Na-sulphide 
  • Dissolved by adding boiling water 
  • Boiled for 100 minutes to complete desolation 
  • Taken in dye bath containing soda ash 
  • Material immersed in dye bath 
  • Raising temperature & adding Glauber’s salt for exhaustion.

2. Method-ii:
These dyes are also insoluble in water and are called specialized conventional Sulphur dyes. Its application method is as below:-

  • Pasting of dye with 25-30 times soft water and reducing agent 
  • Dissolved dye added to dye bath (mixture of soda ash & rongalite C) and boiled for sometime 
  • Material put in dye bath and dyeing carried out for 20 minutes 
  • For exhaustion common salt or Glauber salt is added and dyeing continued for 30-40 minutes.

3. Method-iii:
This method is used for leuco Sulphur dyes; they have distinct affinity for cellulosic fibres. These Sulpher dyes are dyed as in the case of method –I except that little or no Na-sulphide is required for their volatilization.

4. Method-iv:
These dyes are soluble in water having substantivity to cellulosic fibres. They are mixture of Sulphur dyes and Na- sulphide. The dyeing method is as below:

  • Dye pasted with little amount water at 30 degree celsius
  • Diluted with 10-20 times water at same temperature 
  • Dissolved dye is added to required quantity of water in dye vessel 
  • Common or Glauber Salt and soda ash is added in dye bath 
  • Material is put in dye bath and kept at 40-60 degree celsius for 25-30 minutes.

5. Method-v:
These dyes are also soluble in water & are substantive to cellulosic fibres. They are dry mixture of the dyes and Rongallite-C. The dyeing method is as below:

  • Dye pasted with water & dissolved by boiling at 10-20 times soft water 
  • Solution is added to dye bath containing required amount of water
  • Temperature is raised to 90 degree Celsius
  • Material is entered in to the dye bath after 20 minutes
  • Glauber salt is added & dyeing continued for some times.

6. Method-vi:
These dyes are solubilized Sulphur dyes. They have no affinity towards cellulosic fibres. Chemically they are thio-sulphuric acid derivatives and are applied either by Na-sulphite method or by Na-Hydrosulphite method.

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Mazharul Islam Kiron is a textile consultant and researcher on online business promotion. He is working with one European textile machinery company as a country agent. He is also a contributor of Wikipedia.


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