Transformers Foundation Report Digs into Indigo Dyeing Data
Indigo may dye denim blue, but a new report from the Transformers Foundation notes that claims around the popular dye have often led to greenwashing since they are based on outdated information.
Looking to rectify this, the organization established the Indigo Council last year to study indigo dyeing with the help of denim mills. Transformers Foundation’s resulting “A Reference for Water Consumption During Indigo Dyeing” report was based on data compiled from seven mills around the globe: Advance Denim, Candiani Denim, Crescent Bahuman Limited, Diamond Denim, Naveena Denim, Orta Anadolu and Soorty, with independent oversight from Bluesign and technical expertise from machinery firms Karl Mayer and Morrison Textile Machinery Co.
Paolo Leidi, technical director at the Transformers Foundation, spoke with Carved in Blue about the importance of scientifically measuring indigo’s water footprint and why water use varies across different dyeing processes.
Carved in Blue: Why are benchmark reports like this one so critical to driving sustainability forward in the denim industry? Why was it important to study indigo dyeing in particular?
Paolo: Our denim industry still relies on personal experience and background, most of the time based on empiricism rather than science. Our approach compared the data from seven top mills, and we have demonstrated in a simple way that, by approaching a process in a scientific way, it is possible to optimize the use of resources—water in this case—without compromising the quality of results.
Carved in Blue: Given that parameters can change the amount of water used from day to day, how can mills better report their water usage? How should they account for variables like weather?
Paolo: There are technical possibilities to measure in a very accurate way the water usage, and modern technology allows collecting all this data digitally. They can be used on all the running indigo dyeing machines. The usage of water is mainly connected to the depth of the color and the yarn count. In our study we have considered the same process in all the mills. External variables (like weather) are affecting washing water consumption only to a limited extent.
Carved in Blue: What is the balancing act between reducing water consumption and maintaining dye quality? How do you see this playing out at mills?
Paolo: None of the mills participating in the study has compromised on quality to reduce water consumption. They have run processes as per their standard methods. It is just a matter of a more scientific approach to calculate the minimum quantity of water that is necessary.
Carved in Blue: In the report, you position pre-reduced indigo as the better choice. Is it reasonable for the whole industry to make this switch? Are there any tradeoffs compared to powdered format dyes?
Paolo: The advantage of pre-reduced indigo is a significant reduction in the use of hydrosulphite. For the rest, the dyeing process is the same as it is for powder indigo. Moreover, the use of pre-reduced indigo requires tanks and pumps, but it makes the dye bath preparation much easier and safer for operators and, in certain cases, it also allows for deeper shades.
Carved in Blue: How do you see this study helping the industry make decisions surrounding their indigo dyeing processes and strategies?
Paolo: We wanted to make all the industry players as well as buyers to start considering that there is the possibility for a better industry that can be achieved by everyone just using a more scientific approach to production processes avoiding the “it has always been done like this” philosophy.
Carved in Blue: What are the remaining challenges of collecting data on indigo dyeing’s water impact? Were there any data points you weren’t able to capture?
Paolo: We have focused on the water consumption in the post-dyeing phase. We encourage mills to extend this research to the entire consumption, including even the water used to clean the machine.
Carved in Blue: What do you see being the biggest driver for water reduction efforts going forward? Will it be scarcity, regulation, or something else?
Paolo: Water is essential for life: We would like this to be the driving idea. Unfortunately, often this is forgotten, and we need regulations to oblige the industry. Regulations are there to preserve this resource sometimes due to scarcity and, in general, to preserve the planet.