Yarn Dyeing

Yarn Dyeing
15 January, 2020

For producing handloom fabric, the yarn is dyed in their hank or coiled form. Dyeing is a crucial pre-loom activity. Though handlooms are typically woven by hand and are decentralised in nature, colouring or dyeing with different colours has now emerged as a centralized activity.

Dyes or the colourants are actually the intense-coloured substances, which impart permanent colours to these handlooms. Both natural and chemical colourants are used for dyeing the coiled yarns or the hanks. This dyeing process is done in small lots using hands. 

Dyeing in the handloom industry is carried out in small and medium-sized dyeing blocks or houses located in the villages. These blocks or houses are equipped with everything required for dyeing the handlooms in small and huge lots as well. 

A.    Chemical Dyeing: - 

One of the most significant aspects you need to know before getting into the depth of this chemical dyeing process is the discovery of the benzene structure in the year 1865. It had a great impact on the dyestuff industry and organic chemistry. Since then, it was steadily followed until 1956 when a huge number of different types of chemical dyes were made to use for dyeing in the textile industries. These dyes are still being used in these industries. Many reactive dyes of bright colours were also made in 1956, to meet the market demands of brighter shades like turquoise, reds, scarlet, and more. These brighter hues are easy to apply and have proved to be much better in terms of fastness and quality. With these reasons, these modern dyes have made a place in the worldwide textile industries today. 

Mordant: - 

It is a chemical substance, which helps in fixing the dyes or simply binding the colours to the fibre. 

Direct dyes: - 

When direct dyes are used, the fibre is actually immersed in the dye without using a mordant. Direct dyes have an extremely high substantivity but at the same time come with a disadvantage too. Direct dyes have the tendency to get washed or faded soon because of their weak bond with the fibre. 

Sulphur dyes: - 

Sulphur dyes are prepared by reacting sulphur with various organic compounds. These types of dyes are pretty inexpensive but are quite dull in colour at the same time. These dyes are often used for producing a jet black colour on cotton at much lower costs. Unlike the direct dyes, sulphur dyes have much better wash fastness but at the same time, are a little sensitive to bleach. These dyes on fabrics, especially some of the blacks, often get decomposed under humid and warm conditions, which ultimately reduce the fabric strength. 

Reactive dyes: - 

Reactive dyes do not contain any heavy extractable metals or any other pollutants or toxic substances. This makes the dyes environment-friendly or the azo-free chemical dyes. Reactive dyes have a low impact on the synthetic dyes, which form covalent bonds with the cotton fibres instead of just remaining as the independent chemical entities within the fibres. This also results in brighter and long-lasting colours. 

Vat dyes: - 

Vat dyes are insoluble in water because of which a special process is taken for fixing the colours on the fibres. Excellent colours that are fast and light are obtained from the vat dyes. Indigo is one such brilliant example of a vat dye. 

B.    Natural dyeing: - 

Natural dyes are extracted from the bark of trees, flowers, insects, rust, minerals and several other natural materials. A sub-category of natural dyes is the vegetable dyes. Wool is one of the best fibres that are dyed using these natural options. Cotton is also often dyed with these colouring materials. Natural dyes or fabrics dyed with these are always recommended to be washed in cold water or simply dry cleaned to retain the colours as the relative permanence of these natural dyes are much less than the chemical dyes.

Natural Indigo dyeing: - 

Indigo dyeing process neither contains any harsh chemicals not any kind of toxic metals. Any natural fibres can be dyed with this process. Indigo dyeing was first introduced in the late 2000 BC. In the first step of this dyeing process, the fibre colour is changed from blue to yellow and then slowly to a bright green shade and then slowly the air alters it to a beautiful, and rich blue that’s indigo. Till now, it is considered as a fast and clear natural blue. 

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