Not only were huge amounts of fabric woven in Bengal, the area was also a prime producer of the indigo plant, from which the indigo dye was extracted. This natural dye was widely used before the advent of chemical dyes in the nineteenth century. In fact, the rich blue colour provided by the dye is still sometimes used for dyeing denim. Bengali dye masters had special recipes for producing the desired colours, just as chefs have recipes for achieving desired flavours. However, as was the case with the traditional handloom fabrics, indigo dye production also gradually declined. The problems of the indigo industry were principally a result of two factors. First, because indigo was a cash crop, the British administrators in this part of the empire forced farmers to grow the indigo plant in order to increase the administrators' profits. Unfortunately, the indigo plant is nitrogen depleting and thus exhausted the soil very quickly. The farmers received little real income from the crop since the British kept most of the profits, and in times of economic hardship, such as when the indigo price fell, they were unable to survive by eating their produce, unlike farmers who grew staples such as rice or wheat.
Another reason for indigo's gradual disappearance as a dye was the unpredictable nature of the plant. Sometimes one farmer would have a good harvest, while his neighbour would not be able to produce anything. The combination of poor yields and the unpredictability of the crop gradually led farmers to cease growing the plant and moving on to other, more profitable crops.
Dr. Banerjee in his report on "Dyes and Dyeing in Bengal" in 1896-97 also makes special reference to the bright, colourfast fabrics of the tribals, particularly the Mughs of Cox's Bazaar. Natural dyes have been used in wooden toys, mats and basketry, ivory, pith and all kinds of decorative paintings but its real affinity is to textiles, be it cotton, wool, rayon or silk. Names like piyaji, surmai, basanti, asmani, nilambari, sonali, abir and dhani, dominated the world of colours in Bengal. Bangladesh has a rich repository of dye producing plants which yielded an initial set of fifteen colourfast dyes within a very short time. However, an extensive field survey carried out across the country indicated that the pernicious influence of synthetic dyes had all but eliminated this indigenous craft. Only in some of the tribal areas, nominal amounts of vegetable dyes continue to be used. Training courses conducted across the country, workshop and exhibitions held over a two year period as well as wide media coverage enabled the reintroduction of natural dyes. Since then the emphasis has been shifted from research to greater dissemination of the dyeing skills and extensive cultivation of dye yielding plants, particularly the cultivation and extraction of natural indigo. Fifteen additional colours have been added to the existing range bringing the total to thirty standardised shades, which singly, or as compound colours, yield a wide variety of colourfast dyes.
TECHNIQUE AND PROCESS
The appliances for dyeing are very basic and simple. The dye house itself can be just a spacious shed with sufficient light and circulation of air. A verandah for drying the dyed yarn in the wet season is most helpful although printing on many days is not recommended. Sun dried fabrics and fibers give the best results during production but aftercare requires them to be dried in the shade, away from the sun.
Natural dyes react to certain types of vessels such as iron and aluminum ones. It is, therefore, essential to choose the vessel carefully. Earthenware is acceptable but since they are porous they absorb the liquid dyes. So each dye has to have its separate vessel otherwise one color will affect another. The best results are obtained from copper or stainless steel containers; these do not react to dyestuffs and are very hardy. For scouring, washing and bleaching large gamlas (earthen vessels) are ideal. For storing natural pitchers are also most suitable.
The size of the containers depends on the amount of material to be dyed at a time. They should be large enough to allow sufficient room for easy stirring of the material. The amount of water required for dyeing yarn is in the ratio of 1:20, therefore the vessel should be large enough to hold such a load easily.
But during the last thirty years major effort has been made by individuals, craft development groups and government agencies to research and revive the use of natural dyes. Many dyers and weavers have been trained to make and use natural dyes. Craft agencies and textile houses have also realized that natural dyes are environment friendly, and this has created a niche in the market. The results are to be seen in the dissemination of knowledge of the use of natural dyes for textile and embroidery yarns, as well as for other craft items.