Every living organism uses the natural resources for their growth and prosperity. Humans are considered the best among them also depends on these environmental elements for their survival. The ancient cave painting, discovery of remnants of dyed cloths in excavation cites of various civilization indicates that the art of dyeing with natural colours were age old and has close relations to our civilization in every nook and corner of the globe.

First scientific analytical explanations come from Newton’s light experiment with prism where we acquainted with colours of rainbow. Colours play an important role for miscellaneous needs in daily life, as well as emotional development and pleasure.

In our natural resources we get colours from plants, animals, microorganisms and minerals. The colours obtained from plants, animals and microorganisms considered as organic. There are more than 4500 plants from where we get natural colours. Although all plants possesses natural colours which may or may not useful to us. Some animals also provide excellent colours too. We also get some natural colours as a byproduct of an industrial process. Until the discovery of synthetic dye in the middle of 19^th century the natural dyes flourish to a large extent.

The blue dyes obtain from indigo (Indigofera tinctoria), various red sheds from Madder (Rubia cordifolia), Brazil wood (Caesalpina sappan) Morinda (Morinda citrifolia) Safflower (Carthamus tinctorius) yellow colour from turmeric (Curcuma longa) Saffron (Crocus sativus), Barberry (Berberis aristata), Myrobolan (Terminalia chebula), Marigold (Tagetus erecta), Dolu (Rheum nobile), different shades of orange red obtain from Annatto (Bixa orellana), orange yellow from flame of the forest (Butea monosperma, Kamala (Mallotus phillipensis) were very few examples. Different shades of colours may procure by increase or decrease of colorants or mixing of two or more colorants with different combinations.

Cochineal was an insect (Dactylopius coccus) originated popular red dye. The byproducts of Lac industry also produce useful brown red dye. The popular host of lac insects (Kerria lacca) is Sissam and Butea plants which are very much common in Indian subcontinent.

Similarly red ocher, yellow ocher, charcoal black, azurites are few examples of mineral pigments found in nature.

The detail research on chemical aspects of this naturally occurred colour components from vegetable origin proves that natural dyes have a complex chemical constitution in comparison to synthetic dye. They are categorized as Indigoid, Anthraquinone, Napthoquinone, Flavonoid, carotenoid and tannin based dyes and others.

W.H. Perkin accidentally synthesis a mauve colour while preparing quinine from coal tar. This was the first synthetic dye in 1856. Next year he established his own factory near London to produce synthetic dye commercially. Later several chemical and pharmaceutical industries were set up by different entrepreneurs to produce various synthetic chemical based products. 

The synthetic dye became highly popularized by its low cost, better fastness and varieties of shades. But the synthetic dyes are non biodegradable, non renewable resources and harmful in nature mostly derived from petroleum resources. The fact was understood after one and half century. The synthetic dyeing industries produce highly polluted effluent water which mixed with river and local water bodies. It directly or indirectly effect ecosystems, local population, wild animals even agricultural field by irrigation of polluted water. Lack of interest in environmental importance or less interest to invest in effluent treatment plant ultimately affects the marginal communities, farmer’s livelihood and wide range of macro and micro organisms.  But, the synthetic dye still popular because natural dyes have some limitations too. The natural dyeing processes are very tedious, limited shade range, seasonal availability of dye resources, non reproducible shade and poor fastness properties and  less suitable for industrial set up.

The advantages of natural dyes are, it obtains from renewable natural resources like flowers, fruits, leaves, barks etc. The components of natural dye are easily biodegradable by microbial action, light or water treatment. The pomegranate rind, onion skin, safflower petals are byproducts of agro processing industries. The leaves from deciduous trees always renewable resources can harvested without any environmental destruction.

Apart from textile industry, natural dyes also used in food colouring (turmeric, saffron), pharmaceuticals, cosmetics (annato), painting, home décor and craft items etc. In rural villages local artisan group may produce dyestuff by locally available plant material for their traditional craft items.

Most of the dye yielding plants has medicinal properties like Indigo, Turmeric, Myrobalan, Teminalia, Tagetus and many others. By cultivating these plants not only to get dye or medicine but also lead to higher carbon fixation in the form of biomass synthesis. The leguminous plants like Indigo help to fix nitrogen into the soil by nodule forming bacteria in roots. The crop rotation by regular cash crops with dye yielding plants may increase fertility of soil. The residues of plant parts after extraction of dye are also useful as green manure.

Now a days significance of natural dyes valued by traditional dyers and printers, selected ethnic communities, textile designer, various artisan groups, hobby groups and research institutions like Universities, NGO’s and museum communities. Their untiring efforts to popularize the natural dye to civic societies. Other important aspect is to prevent the loss of indigenous knowledge and technique by documenting natural dye making process which used by remotely located tribal population’s, generation after generation.

To increase sustainability in this field some measures may be taken like uses of waste places for cultivation of dye yielding plants because priority of land always given to cereals or pulses. High dye yielding varieties may develop by hybridizing, gene transfer and other modern techniques. Biotechnological tools may apply to transfer dye producing genes to fast growing harmless microorganism to resolve issue of land availability. Try to avoid metallic mordant which contains heavy metals to fulfill global organic textile standards. This small scale industries may facilitate by providing infrastructural facilities and tax relief by local government. Mass scale awareness on importance of organic products among traders and end users.

To safeguard the environment of Planet earth, Scientist, Industrialists, policy makers and users are paying more attention on renewable resources. Various national and international bodies are vigil to implement treatise on environmental safety and asses the progress of commitment of countries in regular manner to reach the goal.

About Author

Manas Bhaumik is a Scientist in Botanical Survey of India Industrial Section Indian Museum, Kolkata. His field of specialization are Taxonomy, Biodiversity and conservation of wild plants of Eastern Himalaya. About 55 research papers and 7 book chapters published in national and international pear reviewed Journals.