How are Different Dyes Made?
7:59 AM
Dyes are coloured substances which impart their colour to the fabrics on which they are applied and for which they have a chemical affinity. Until the middle of the last century, the only dyes available were natural products obtained mostly from plants and flowers. Their range was limited. These natural dyes included: woad, a blue dye obtained from the plant woad; indigo, another blue dye from a plant. Some other dyes such as mader (red), saffron and turmeric (yellow) were extracted from the certain kinds of sea-shells.
The most important breakthrough in this field was made in 1856 with the discovery of the first synthetic dye by William Henry Perkin. After this discovery, efforts were made to develop dyes from coal tar. As a result of these efforts, several thousand dyes were synthesized subsequently. These synthetic dyes were satisfactory when used with animal fibres such as wool; but they were easily washed off from vegetable fibres like cotton. This difficulty was overcome by treating the fibres with metal salts or with solutions of these salts in tannic acid before dyeing.
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