Dyes

Historically, natural dyes have been used to color clothing and textiles. Natural dyes generally require a mordant (a color fixer), which are metallic salts of aluminum, iron, chromium, copper and others, for ensuring the reasonable fastness of the color to sunlight and washing. By the mid-1800’s chemists began producing synthetic substitutes for them that possessed superior color vibrancy and color retention through wash and exposure to sunlight. By the early part of the twentieth century only a small percentage of textile dyes were extracted from plants. Lately there has been increasing interest in natural dyes, as the public becomes aware of ecological and environmental problems related to the use of synthetic dyes. Use of natural dyes cuts down significantly on the amount of toxic effluent resulting from the synthetic dye process.

Napthol and Reactive dyes are two sets of chemicals which when reacted with each other produce a third chemical essentially colourful in nature. Fabric is dyed in one and later printed with the other. The chemical reaction produces a third colour. However, the biggest drawback of this process is that there are just a few chemicals available which produce colours when reacted with each other.

Vegetable and Natural dyes have been historically of great importance, and these dyes have acquired even greater importance now because of their eco-friendly nature. Some of the commonly use dyes in this category are Bagru Black, Bagru Red and Indigo Blue. Bagru Black is derived by mixing acidic solution of iron - often rusted nails/horse shoes etc. with jaggery (country sugar), and allowed to rot for about 10-15 days. Many other natural substances used for producing dyes are pomegranate skins, bark of mango tree, vinegar, slaked lime etc. Bagru Red is made by combining a source material such as alizerine with alum, the results ranging from pink to deep red. Indigo Blue is obtained from the indigo bush found throughout India.