Classification of Sulpher Dyes

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

Dye pasted with cold wateràAdd required amount of Na-sulphideàDissolved by adding boiling wateràBoiled for 100 minutes to complete desolationàTaken in dye bath containing soda ashà Material immersed in dye bathàRaising temperature & adding Glauber’s salt for exhaustion.

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

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

3. Method:
This method is used for leuco Sulpher 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:
These dyes are soluble in water having substantivity to cellulosic fibres. They are mixture of Sulpher dyes and Na- sulphide. The dyeing method is as below:

Dye pasted with little amount water at 300Cà Diluted with 10-20 times water at same temperatureàDissolved dye is added to required quantity of water in dye vessel àcommon or Glauber Salt and soda ash is added in dye bathàMaterial is put in dye bath and kept at 400-600C for 25-30 minutes.

5. Method:
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 à Solution is added to dye bath containing required amount of wateràTemperature is raised to 900 c à material is entered in to the dye bath after 20 minutesà Glauber salt is added & dyeing continued for some times.

6. Method:
These dyes are solubilized Sulpher 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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