Sustainability has become the main focus for textile industry and their teams are working hard to achieve sustainable development goals in no time. All the factors including raw material as yarn, processing and supply chain are worked on, but Natural dyes is very less touched, may be because of unavailability of data for the calculation of sustainable impacts.
AMA Herbal Laboratories Pvt. Ltd. in India, have made a breakthrough in the dyeing sector by presenting Bio Indigo dye with Life Cycle Analysis (LCA) for the first time. LCA is a scientific, analytic approach in calculating benefits that brands can get on sustainable balance sheet by just switching to Bio Indigo in denim production.
Bio Indigo dye comes in powder form and is certified on "GOTS Version-V", and has "ZDHC", "REACH" to its credit. Its Fastness properties, process of dyeing and method of use remains same or at par with synthetic indigo. Many big denim mills form Turkey, India, Pakistan, China, Italy and Japan are already using Bio Indigo on their rope dyeing machines. Bangladesh Denim world is also showing good response to this concept. Designers love Bio Indigo for its greener cast and the kind of cut effect that it gives.
Bio Indigo dye is obtained from leaves of plant Indigofera tinctoria commonly known as indigo which also exhibits medicinal properties. One of the major characteristics of the Indigo plant is that it is a legume and contributes in fertility to soil. Many coconut farmers have reported higher yields in coconut water by planting Indigo in the periphery. It also acts as a nitrogen source when used as a compost.
Denim and Indigo blue goes hand in hand. Initially denim was made with Natural Indigo only, but now Indigo is also produced synthetically. Synthetic indigo (other name - Indigotin, CAS no. 482-89-3) is produced through chemical process and makes up for the majority of commercially produced indigo dye in the denim industry.
To support their claim of Bio Indigo dye being a sustainable product as well as compare with Synthetic Indigo Dye, AMA Herbal Laboratories have evaluated its environmental impacts using Life Cycle Assessment approach as per ISO 14040/44 standard. AMA Herbal Laboratories entrusted Thinkstep Sustainability Solutions Pvt Limited, a subsidiary of Thinkstep AG, Germany for the LCA study of Bio Indigo dye using GaBi ts Software system and Thinkstep Professional databases and services. The study helped evaluate the various environmental impacts of the Bio Indigo dye and how it stands compared with the Synthetic Indigo Dye.
For dyeing of one kg of cotton yarn, synthetic dye consumption is lesser than natural indigo dye. Thus, to make a fair comparison, the functional unit was defined as one kg of dyed cotton yarn. The inventory used in the study consisted of all the production steps from indigo leaves produced in the farms to Bio Indigo Dye production followed by its use in cotton yarn dyeing. For synthetic dye, similar system boundary i.e. the production of Synthetic indigo dye followed by its use in the cotton yarn dyeing was considered in the study.
Rope dyeing, being the most common technology for dyeing in denim industry was considered. It consists of twisting the yarn into a rope then quickly dipped into Indigo baths. This dyeing technique is considered a superior dyeing technology where better dyeing uniformity is achieved.
Dyeing with Bio Indigo dye has 16% lesser acidification potential, the global warming potential was 9% lower, the primary energy demand was also 8% lower whereas the fresh water demand was 0.4 % higher. The difference in the positive impacts was in the range of 0.4%-23% for various environmental factors defining sustainability of denim.
Additionally, the study was used to compare environmental impacts for production of 1 kg of both the Dyes. Except for fresh water consumption, all the other environmental impacts are 10-100% lesser in case of Bio Indigo Dye.
The key findings of this study are summarized as follows:
The impacts from dyes are highly dependent on the quantity of the dye required. Better utilization of Bio Indigo dye will lead to further impacts reduction.
The impact contribution of dye production in both cases of dyed cotton yarn production, is not more than 8-9% across various impact categories. The major impact contribution comes from the cotton yarn and energy consumption in rope dying process. Use of Bio Indigo dye leads to impact reduction, from the credits,
it generates as a raw material as well as utilization of dye waste water in agriculture as a source of nitrogen.
Decisions as well as the choice of modeling approaches and assumptions can influence the results of LCA.
This study provides Life Cycle Inventory (LCI) and Life Cycle Impact Assessment (LCIA) as regional averages (India) across the industry for dye manufacturing.
Bio-diversity is not assessed in this study due to its limitations in the LCA methodology
Decision should not be taken on toxicity parameters due to their high level of uncertainty. But when compared with Synthetic Indigo Dye, Bio Indigo dye has lesser impacts for sure.
Bio Indigo dye can give denim brands and manufacturers with an sustainable solution of having lesser hazardous environmental impacts. commonly, natural dyes have many advantages over Synthetic dyes. Natural dyes are non-toxic, non-allergic and now one can say they have a reduced negative environmental impacts than synthetic dyes. The water consumption can be reduced by engaging sustainable farming practices. AMA Herbal Laboratories will explore this area as a next step in their LCA journey. To become sustainable, fashion industry needs sustainable materials. Bio Indigo dye thus promises in this endeavor.