They are one of the most used dyes for producing bright black and brown shade on cellulosic fiber products.The chemistry of sulphur dyes dyeing is near similar to vat dyes dyeing.In both case final color is developed by the oxidation process.Although,reactive dyes,azoic color is available but sulphur dyes are preferable for black shade production.
They are so called because sulphur dyes contain di-suphide(S-S) linkage in their chemical structure.Sulphur dyes dyeing process is carried out in alkaline condition.Sulphur dyes are used for both dyeing and printing.
water insoluble dye.
It needs solubilization for application(with reducing agent).
Oxidation is needed for final color development.
Sulphur dye is applied in alkaline condition.
Electrolyte can be added in the dye to enhance exhaustion of dyes.
Fastness properties are averae.
Best suitable for producing black and brown shade on the textile materials.
It is mainly applied on cotton,viscose and staple fiber.
Its exhaustion properties are good.
Most of the times dyeing is carried out in 80-95 degree Celsius.
Sulphur dye is comparatively cheap in price.
The conversion is usually carried out by the treatment with aqueous sodium sulphide solution
Since the leuco form has affinity for cellulosic fibre and since they are sensitive to atmospheric
oxidation, they can be easily oxidised to the parent sulphur dye
Thus they have to be dyed from the aqueous sodium sulphide solution
