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History of Traditional Indigo Dyeing and tie and dye techniques

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Cotton natural Indigo dyeingIndigo is the most common natural dye in Sierra Leone, and several methods (seven identified in this study) are used for its production and subsequent use in fabric dyeing. In general, they involve production either from fresh leaves in the dyepot, leaf fermented into leaf balls but dye not extracted, indigo dye extracted into an insoluble lump, or use of the synthetic dye. In some cases up to four other plant spe cies are added to the dyebath, for example, Morinda germinata (wanda) roots, and Cola nitida fruits (cola), Man gifera indica, Rhizophora recemosa, Jatropha curcas (fignut), and Capsicum frutescens (pepper). Caustic soda, which creates an alkaline pH environment for the three-to-seven day fermentation to proceed; local alum or ash from Sterculia tragacantha (Kobe tree); and a black powder called colmet are also Rusty nails or metal cups, or Alchornia cordifolia (Christmas bush) are also sometimes added to darken the shade. Another method involves mixing the indigo dye with sodium hydroxide and sodium hydrosulfite in a ratio of 1:1:1 in water.

Dyeing is achieved by first washing the fabric with soap and water, then immersing the cloth (a white fabric called bryleon or cotton/polyester poplin) in the dye for different periods of time (varying from hours to three or four days) drying, dipping again, drying, and so on, until the desired shade is obtained. After this, the dyed fabric is washed, dried in the sun, and ironed either traditionally by pounding with a stick on a wooden slab to produce a glossy shine on the cloth, or by using modern forms of ironing.

Apart from dyeing the whole material uniformly, various patterns can be produced by dyeing only parts of the fabric and leaving the remainder undyed. These methods are known as sewing, tie-dyeing, knotting, folding, and resist-dyeing or the use of batik.

Although the dye can be prepared by a variety of methods, the fundamental chemistry of the process remains the same. Essentially the indigo dye is the product of a fermentation reaction catalyzed by bacteria, in an alkaline environment provided by caustic soda, and released from their glucoside, indican.

The indigo plant contains indican a kind of ester or glucose compound of indoxyl. On fermentation by bacterial species present on the plant, indican is hydrolyzed by an enzyme to indoxyl, which is then oxidized to the blue insoluble indigotin, then reduced to the white soluble indigo (leuco indigo), and after dyeing cloth, reoxidized to indigo again on the fabric as shown in, 1822 Many ancient cultures in various parts of the world used stale urine to provide the reducing agent, urea.

Natural indigo dyeing was a very thriving local industry in Sierra Leone, part of the indigenous economy that provided livelihoods for a large number of people in various parts of the country. Although these traditional methods of dye production have al most been driven to commercial extinction, dyeing with synthetic indigo and a wide variety of other colors is booming, serving not only the local, but the international market as well. In this study, the indigenous practices were documented before they are com pletely lost.

Different methods are used for the production of indigo dye in Sierra Leone. It is clear that in all the seven procedures gara leaves and Morinda germinata roots are the main ingredients. Other ingredients provide some variability to the main method used; e.g., the use of Mangifera and Jatropha ostensibly to enhance the color. It is quite possible that some of these other ingredients are acting as mordants; e.g., the roots of Morinda germinata are reported to serve as a fixing agent for the indigo dye. It has been shown that although this Morinda germinata has a very positive effect on the dyeing intensity, the plant does not have any reducing activity; and does not significantly affect hydrolysis of indican, the precursor of indigo. It is possible that the indoxyl released from indican is not oxidized to the insoluble indigo form-it serves as an antioxidant, rather than a reducing agent. These days, some dyers also use a small amount of the synthetic indigo dye to darken the hue.
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