The word ‘dye’ originated from the old English word ‘dag’ or ‘dah’.

Dyeing is the process of applying colors and pigments on fabrics such as yarns, fibers, and other such textiles in order to produce colorful fabrics for various purposes. Dyeing involves the textile being submerged into a chemical solution where the molecules present in the dye bonds with the fiber via absorption, diffusion or bonding due to varied temperature.

Historical shreds of evidence have shown the use of dyes since the primitive age. Nature was the primary source of dyes back then. But, with the advancement in technology, humans have been able to produce artificial dyes to create a wider range of colors and to achieve greater permanence of the dye on fabrics. Different types of chemicals, liquor proportions and temperature are required for the process.

The process of dyeing textiles is a wet process which involves cleaning and bleaching the fabrics before dyeing it. The procedure is carried out in multiple phases of fiber processing, that is, in different forms, such as staple, yarn, fabric, and piece. Acrylic fibers are colored using basic dyes, whereas nylon and protein fibers, for example, wool and silk are colored using acid dyes, and polyester yarn are colored using disperse dyes. However, cotton is colored using various types of dyes, such as vat dyes, modern synthetic reactive and direct dyes. During the first stage of fiber processing, staple fiber is used to achieve a faster result. The fiber is dyed through the process of bulk dyeing where the fabrics are placed in a perforated basket along with the pigment(s) and spun at a high speed, ensuring even distribution of the pigment throughout the fabrics.

History of Dyeing

The earliest evidence of dyed fabrics has been found in a cave in the Republic of Georgia dating back to 34000 BC. Other such evidence has been excavated in a large Neolithic settlement at Catalhoyuk, southern Anatolia, Turkey. The fabrics consisted of red dyes, assumed to be extracted from others, a pigment from iron oxide, derived from clay. Traces of dyeing using plants, tree barks, and insects have been found in China dating back to more than 5000 years. Further pieces of evidence of natural dyes have been found in the Sindh province of Pakistan. The first synthetic dye invented was in 1856, named William Perkin's ‘mauveine’, extracted from coal tar. Alizarin was the first ever natural pigment to be duplicated artificially in 1869. This led to a huge drop in the market for naturally grown madder. The improvement of new, emphatically hued manufactured colors pursued rapidly. By the 1870s naturally produced dyes gradually became extinct.

Types of Dyeing Process

1) Bale Dyeing: This method is used to dye cotton cloth at a low cost. The fabric is passed through a cold water bath where the measured twist provides for the pattern produced by the dye.

2) Batik Dyeing: This is one of the earliest method used by man. Parts of the fabric are covered in wax to ensure that only un-waxed regions will absorb the dye. The procedure can be repeated, using different colors to get varied results. The result is a mottled or streaked effect, like that of machine printing.

3) Beam Dyeing: In this technique, the warp is dyed before weaving. It is placed on a perforated beam and the pigment is forced through the perforations, thus, dyeing the yarn.

4) Burl or speck Dyeing: This method is usually used on woolen fabrics. Any type of colored specks or blemishes is covered using a special type of pigment which comes in various shades and color. The process is carried out manually.

5) Chain Dyeing: This is used on fabrics with low tensile strength. Multiple pieces of cloth are fastened end-to-end and passed via a continuous chain under the dye. This method is used for mass production.

6) Cross Dyeing: This is a very popular method used to achieve varied color effects in the dye bath for a cloth which consists of fibers with varying affinities for the pigment used. For example, a blue dye might cause nylon 6 to have a dark blue shade, nylon 6, 6 a lighter shade of blue, and have no effect on the polyester area, thus, leaving it white.

7) Jig Dyeing: This is done in an open vessel. The textiles move from one roller to another, and then through a deep dye bath until the ideal shade is produced.

8) Piece Dyeing: Dyeing of textiles in pieces is called piece dyeing. It allows the weaving of the products, providing a single color for the material, for example, a green organdy.

9) Random Dyeing: This involves dyeing only certain parts of the yarn. There are three ways of carrying out this process:

The yarn must be dyed in two or more regions and dyed at one side using one color and on the other side using another color.

The pigment may also be printed onto the yarn which is placed on the blanket of the printing machine.

Bundles of yarn on hollow spindles may be arranged in such a manner to form channels, through which the yarn, via air-operated punch. The dyes are passed through these holes by the method of suction. The part of the yarn closest to the punch absorbs the dye and thus, an irregular pattern is generated.

10) Raw Stock Dyeing: The fiber stock is dyed before spinning the yarn. The woolen fibers are decreased and the stock is dried.

11) Solution Dyeing: This method is also known as dope dyeing or spun dyeing; the pigment is bonded-in with the solution and is picked up as the fibers are being produced in the liquor. This method is usually used to dye cellulosic and non-cellulosic fibers. The resulting colors are bright, clear and clean.

12) Yarn-dyed: Yarn which has been previously dried and stored goes through a spinning process in the machine. The process may be carried out while the yarn is either partially or fully immersed in the pigment solution.