The faded blue denim fabric that goes into making of jeans can be a totally eco-friendly product.
Textile research organisation, the South India Textile Research Association (SITRA) in Coimbatore, has developed a process that uses sustainable reducing agent and alkali and natural Indigo to dye denim fabrics. “It is a completely environment-friendly and sustainable process that can be used on a commercial scale,” says Prakash Vasudevan, Director of the Association.
While natural indigo is used for long in the textile industry to give colour to yarn and fabric, the process involved in natural indigo dyeing is usually tedious and can be used only to hand dye a limited volume of fabric or yarn.
“We have replaced the hydrose and alkali used in the conventional dyeing process with eco-friendly products. This can be used in existing machinery, without additional capital investment, to dye large volume of fabric,” says K.H. Prabhu, Senior Scientific Professor at SITRA, who had done the project.
The ₹17.28 lakh research project took off in January this year with 50:50 funding from the Ministry of Textiles and Industry and partner Sri Kannapiran Mills.
Most of the domestic denim product manufacturers import synthetic Indigo from countries such as the U..S and China.
Unconfirmed estimates are that nearly 22,000 tonnes of synthetic Indigo is used in the country a year. The textile processing sector uses synthetic indigo, hydrose as reducing agent, and sodium hydroxide as alkali in the dyeing process. This has corrosive effects on the effluent treatment plants, affects the treatment plant microbes and releases toxic gas, according to the research Association.
Natural indigo (Indigofera tinctoria) is grown in India and when it is used with environment-friendly reducing agents and alkali, the entire process becomes sustainable.
The association completed the lab tests a couple of months ago and industrial bulk trials about 10 days ago. “The Green Denim Technology” is now ready for commercial use. SITRA plans to apply for patents, nationally and internationally, for the technology.
The industry partner for the project will have the technology for five years, says Mr. Vasudevan.
B. Sri Hari, president of Sri Kannapiran Mills, said the company had started commercial production of the eco-friendly denim fabric and planned to target brands.
“How this technology helps is in the process of washing the garment, as natural Indigo is used,” he said.
