Do you know? The first synthetic dye, picric acid, was prepared in the year 1771 from the natural pigment, indigo.

Have you ever wondered what gives the cloths your the jazzy colours, what gives the printer you use with your desktop the multicoloured printing. The answer to all this lies in the synthetic dyes. No doubt Synthetic dyes today has evolved into a multi billion dollar industry. Almost all the colours that you see today are Synthetic dyes. They are widely used for dyeing and printing in a broad range of industries. There are over 10,000 dyes, and the annual production globally, exceeds over 7 × 105 metric tones. They have become indispensable to the dyeing units specifically to textile units. It is a fact that fashion would not have so much vibrancy in terms of colours and generated so much hype and enthusiasm, were it not for the synthetic dyes. The synthetic dyes, can be named according to the chemical structure of their particular chromophoric group. For example, diphenylmethane derivatives, triphenylmethane compounds oxazine compounds, xanthene compounds, Azo dyes to name a few. Out of these Azo Dyes are one of the most popular varieties of synthetic dyes. Today it is being used up to 90% in the dyeing units, as they are versatile and simple to synthesize. Most of the synthetic dyes with a few exception are aromatic organic compounds which can be divided into groups like non-ionic (oil soluble), cationic, and anionic. A typical example of Cationic dye is Methyl violet, while Azo dyes are anionic dyes.

Synthetic dyes can be primarily made from aniline or chrome. Aniline dyes are obtained from chemical processes and is defined as a class of synthetic, organic dyes. Today the term dye is almost synonymous with any reference of synthetic organic dye or pigment. Aniline dyes are classified based on their degree of brightness or according to light fastness. They are also called coal tar dyes, because the synthetic aniline dyes were made up of coal tar initially, but they faded easily when exposed to sun light. While Chrome dyes were color fast and non-corrosive.

Since textile units are predominant consumers of most of the synthetic dyes, so it would be worthwhile here to mention the types of synthetic dyes that are available for use in the textile dyeing process.

The following parameters can serve as a guideline for synthetic dyes:-

• Fading
• Machine wash ability
• Boiling
• Perspiration
• Dry cleaning
• Hot pressing
• Steam pressing
• Salt water
• Gas fume fading (from oil heaters)
• Fastness assessments

Although the synthetic dye production when it came into being was basically for serving the textile industry but many subsequent applications later on has been developed. Today synthetic dyes are used in a multitude of industries that includes the following besides textiles. Medicine, chemistry, and other related fields. Commercial products like plastics, paint, printing ink, rubber, cosmetics etc.