Университети кимё – технология факультети

INDIGO EXTRACTION 
a
Eshchanova A.K., 
b
Smanova Z.A.
 
a
Khorezm Mamun Academy 
b
National university of Uzbekistan 
Indigo, which is still used and known as the earliest most popular dye, is the 
blue color used as a colorant for painting and dyeing. The traditional methods of 

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extraction of indigo from the plants are Indigofera tinctoria and woad Isatis 
tinctoria which is different from each other. This plant called a shrub originally is 
grown in the tropics, particularly in India, Southeast Asia and Middle East [1]. 
Extraction indigo from plant according to the method of Indigofera tinctoria
Indian method: Cultivation of indigo for extraction of dye is considered as 
an old method in India. Although there are several variations, traditionally the cut 
plant is tied into bundles, put into the fermenting vat to be drown in clean water. 
The vats, which are usually made of brick lined with cement, have an area of about 
400 square feet and are 3 feet deep, arranged in two rows over each other. The top 
vat is known as the fermenting vat while the bottom as the beating vat [2]. The 
indigo plant is put a wait up to 10–15 hours until natural fermentation is 
completed. The liquor, which varies from a pale straw colour to a golden yellow, is 
then run into the beating vat, where it is agitated either manually or mechanically. 
The color of the liquid initially becomes green, then blue, and finally indigo is 
separated as flakes and is precipitated to the bottom of the beating vat. The indigo 
is allowed to thoroughly settle, when the supernatant liquid is drawn off. The pulpy 
mass of indigo is then boiled with water for a few hours to remove impurities, 
filtered through thick woolen or coarse canvas bags, then pressed to remove as 
much moisture as possible, after which it is cut into cubes and finally air dried [3]. 
Extraction indigo from plant according to the method of Isatis tinctoria 
To the traditional method of producing indigo dye (also called woad) from 
woad, the leaves are crushed to a pulp, which is kneaded into balls, which is then 
allowed to dry for several weeks. These dried balls could then be stored. The balls 
are needed to be couched. The couching meant crushing the balls into powder and 
wetting it and allowing the material to ferment for several weeks. After couching, 
the woad is dark clay like material that is dried and packed tightly before use[3]. 
The dye from woad is very impure and it gives only light colours, whereas the 
indigo from the tropics is of better quality and could be used to produce darker 
blues. This is the reason why the exotic indigo from the Indigofera species can 
overtake woad so completely. The modern extraction method of indigo from woad 
uses the water solubility of the indigo precursors in steeping the leaves in hot water 
[4]. The precursors are broken down to indoxyl and sugar moieties by enzymes in 
the plant. Subsequent aeration produces indigo by oxidation of indoxyl. 
References 
1.
Ratnapandian, S., Fergusson, S.M., Wang, L., Padhye, R., May 15–17, 
2012. Sustainable developments in printing cotton fabric with indigo. In: 88th 
Textile Institute World Conference Proceedings, Malaysia, pp. 99–107. 

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2. Agarwal, S.,June 10,2011. History, Chemistry and Application of Indigo 
dyes.
3. Aino, K., Narihiro, T., Minamida, K., Kamagata, Y., Yoshimune, K., 
Yumoto, I., 2010. Bacterial community characterization and dynamics of indigo 
fermentation. FEMS Microbiol. Ecol.74 (1), 174–183. 
4. Anbu Kulandainathan, M., Muthukumaran, A., Patil, K., Chavan, R.B., 
2007b. Potentiostatic studies on indirect electrochemical reduction of vat dyes.