Page 90 - Shawl Weaving Artisan - TT

Textile & Handloom Related Theory for Exercise 1.6.55-65
Shawl Weaving Artisan - Wet Processing

Methods of fiber, yarn and fabric dyeing

Objectives: At the end of this lesson you shall be able to
• explain dyeing and methods of dyeing.

Dyeing and methods of dyeing 5 Chain dyeing: Used when yarns and cloth are low
in tensile strength. Several cuts or pieces of cloth are
The process of applying colour to fibre stock, yarn, or
fabric is called dyeing. There may or may not be thorough tacked end-to-end and run through a continuous chain
penetration of the colorant into the fibres or yarns. Textile in the dye colour, allowing for high production.
dyes include acid dyes, used mainly for dyeing wool, silk, 6 Cross dyeing: A popular method where varied
and nylon, and direct or substantive dyes, which have a colour effects are obtained in one dye bath for cloth
strong affinity for cellulose fibres. Mordant dyes require containing fibres with different affinities for the dye
the addition of chemical substances, such as salts, to used. For example, a blue dyestuff might give nylon
give them an affinity for the material being dyed. They 6 a dark blue shade, nylon 6,6 a light blue shade, and
are applied to cellulose fibres, wool, or silk after such have no affinity for polyester, leaving it white.
materials have been treated with metal salts. Sulphur 7 Jig dyeing: Done in a jig, kier, vat, beck, or vessel
dyes, used to dye cellulose, are inexpensive but produce in an open formation of the goods. The fabric goes
colours lacking brilliance. Azoic dyes are insoluble from one roller to another through a deep dye bath
pigments formed within the fibre by padding, first with a until the desired shade is achieved.
soluble coupling compound and then with a diazotized
base. Vat dyes, insoluble in water, are converted into 8 Piece dyeing: The dyeing of fabrics in cut, bolt, or
soluble colourless compounds by means of alkaline piece form. It follows the weaving of the goods and
sodium hydrosulphite. These colourless compounds are provides a single colour for the material, such as blue
absorbed by the cellulose, which is subsequently oxidised serge or green burgandy.
to an insoluble pigment. Such dyes are colourfast. 9 Random dyeing: Colouring only certain designated
Disperse dyes are suspensions of finely divided insoluble portions of the yarn. There are three ways of doing
organic pigments used to dye hydrophobic fibres such this type of colouring: skeins may be tightly dyed in
as polyesters, nylon, and cellulose acetates. Reactive two or more places and dyed on one side of the dye
dyes combine directly with the fibre, resulting in excellent with one colour and the other side with another; colour
colourfastness. The first ranges of reactive dyes for may be printed onto skeins spread out on the blanket
cellulose fibres were introduced in the mid-1950s. Today, fabric of the printing machine; or cones or packages
a wide variety is available. of yarn on hollow spindles may be arranged to form
Methods of dyeing channels through which yarn and dyestuff are drawn
by suction, achieving random effects.
1 Bale dyeing: A low-cost method to dye cotton cloth.
The material is sent without scouring or singeing 10 Raw stock dyeing: Dyeing of fibre stock before
through a cold-water bath where the sized warp has spinning of the yarn, following the degreasing of wool
an affinity for the dye. Imitation chambray and similar fibres and drying of the stock.
fabrics are often dyed this way. 11 Solution dyeing: Also called dope dyeing or spun
2 Batik dyeing: One of the oldest forms of dyeing, dyeing. The pigment colour is bonded in the solution
originated in Java. Portions of the fabric are coated and picked up as the filaments form in the liquor.
with wax so that only unwaxed areas take on the dye Both cellulosic and non-cellulosic fibres are dyed to
matter. The operation may be repeated several times, perfection by this method. The colours are bright,
using multiple colours for a mottled or streaked effect, clear, clean, and fast.
imitated in machine printing. 12 Yarn dyeing: Yarn dyed before weaving, following
3 Beam dyeing: The warp is dyed before weaving by the spinning of the yarn. It may involve partial or total
winding it onto a perforated beam and forcing the immersion of the yarn.
dye through the perforations, saturating the yarn with Process of dyeing
colour.
The dyeing of a textile fibre is carried out in an aqueous
4 Burl or speck dyeing: Mostly done on woollens solution known as the dye liquor or dye bath. For true
or worsteds. Coloured specks and blemishes are dyeing to occur, both coloration and absorption are
covered by using special-coloured inks in many crucial.
colours and shades. It is a hand operation.

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