SADFA 2 Dyeing Technology (Cellulosic Fibres)



Brief classification of colourants according to application type:

  • Acid dyes
  • Direct dyes
  • Reactive dyes
  • Vat dyes
  • Sulphur dyes
  • Disperse dyes
  • Basic dyes
  • Chrome dyes
  • Azoic dyes


Constituents, structure and properties. Hydrocellulose, oxycellulose. Action of acids and alkalis. Mercerization.


Impurities, pH, purification, hardness and effluent treatments.


Soap, anionic, cationic, amphoteric and nonionic.


Singeing, desizing, scouring, mercerisation. Bleaching (hypochlorite, chlorite, peroxide), fluorescent brightening agents. Advantages and disadvantages of various bleaching agents.

Theory of Dyeing

Dyeing of cellulose with direct dyes.

Direct Dyes

Properties and application. Aftertreatment.

Sulphur Dyes

Application to yarn, knitted goods, woven fabrics. Pad, jig, pad-batch, continuous dyeing, pad-steam. Polyester/cellulosic blends. Effluent treatment. Fastness properties, common faults. 

Vat Dyes

Types, reducing agents, vatting, batch dyeing. IN, IW and IK classes. Semi-pigmentation, pre-pigmentation, acid leuco and continuous methods. Loose stock, sliver, yarn (packages and hanks), woven, semicontinuous – continuous, knit goods, faulty dyeing, solubilised vats.

Azoic Dyes

History. Coupling components. Diazo components., Continuous and batch dyeing of stock, sliver, tow, hanks and knitted goods. Fastness properties.

Reactive Dyes

History and chemistry. Cold dyeing, hot dyeing types and reactivity. Package, winch, jets, semi-and fully-continuous sequences possible. Aftertreatments and fastness problems.


Types and application methods.

Polyester/cellulosic Blends

Blends Dyeing procedures for polyester/cellulosic blends.

Colour Selection

Dyestuff selection versus colour range. Reasons for selecting a certain class of dye, eg fastness, hue and cost.

Finishing Sequences

Resin finishes for crease resistance. Special finishes for stain repellency, flame retardancy, waterproofing and softening.


Machinery used in processing.