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Textile Dyeing-4 

PIGMENT COLOURING 

Pigments are completely different substances for colouring textiles. Pigments, unlike dyes, are

colouring substances which are insoluble in water and do not unite or combine in any way withthe textile fibre. Pigment particles are microscopic-sized, coloured chips which are held on the

surface of a fibre by resin binding agents.

Pigments cannot be applied to fibres or yarns, but only to fabrics as solid colour or as prints.

Since the pigment particles do not dissolve in water and do not easily penetrate the fabric, they

must be forcibly squeezed into the cloth so that the inside fibres will be coloured.

The pigment colour is usually mixed with a resin binder and applied as a resin/pigment mixture.

In order for the pigment to adhere to the fabric, the resin must be heated in a process known as

curing.This step, done after the pigment/resin mixture is applied to the fabric, involves heating

the material to temperatures between 300°F and 400°F from 70 seconds to several minutes.

Favorable Properties

A. Pigments can be applied rapidly and economically. They come in a wide variety of available

colours and they result in excellent colour shade matching from lot to lot.

B. Since pigments do not combine or react with the textile fibres (as dyes do), they may be used

with any fibre.

C. Many pigment colours have excellent fastness to light and are used extensively for draperies

and curtains.

Unfavorable Properties

A. Fabrics coloured with pigments will show loss of colour and fading with each succeeding

cleaning (laundering or dry cleaning) because the resins holding the pigment become separated

from the fabric. The effect is more serious on dark shades.Most colours show a distinct faded-out

appearance by about the fifteenth to twentieth cleaning.

B. The resins used in conjunction with pigments cause stiffening of the fabric to which they are

applied.This effect is minimal in light colours, but can be serious in dark shades. The use of 

softeners in finishing will reduce the stiffness.

C. Colour loss by crocking (rubbing) is encountered in pigment coloured fabrics. Again, the

effect is minimal in light colours, but can be serious in dark shades.

SOLUTION DYEING 

Solution dyeing or dope dyeing, is unlike either of the two categories (dye and pigment)

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described earlier in this chapter. Solution dyeing is a method of colouring that is actually part of 

the manufacturing process of man-made fibres. In this method, the colouring agent is added to

the liquid spinning solution of man-made fibre before it is extruded from a shinnerette.The liquid

spinning solution is sometimes called fibre dope, hence the term "dope dyeing" The colour

becomes part of the fibre itself and is thus permanent.

Important Features

A. Solution-dyed colours are practically fade proof under all common conditions of use. Their

fastness to light is particularly outstanding. Fabrics made from solution-dyed yarns are thus well-

suited for draperies, automotive fabrics and other applications where long sunlight exposure is

anticipated.

B. Unfortunately, solution-dyed materials are available in only a limited range of colours

because the systems for the manufacture of man-made fibres require high and continuous outputs

from the machinery used. The required time to clean up and change colours makes frequent

machine changes economically unfeasible. As a consequence. only a limited range of standardand popular colours is produced by this method. Fibre producers will sometimes accept orders

for special colours, but very large production orders would be required.

Solution-dyed yarns are not widely used in fashion apparel fabrics because the range of available

colours is too limited to satisfy the great variety of colours needed for the fashion markets.

Reasons for Use

Solution-dyed materials are used where permanence of colour over a long period is required.

Applications include automotive seating and carpeting. household and outdoor carpeting and

upholstery and drapery fabrics. Almost perfect colour reproduction consistency from dye lot to

dye lot can be achieved.