March 07, 2019

Technology is being developed to reduce water use in dyeing but the use and abuse of water to dye clothing continues

Textiles leave one of the largest water footprints on the planet and dyeing poses an especially big problem. Dye houses in India and China are notorious for not only exhausting local water supplies, but for dumping untreated wastewater into local streams and rivers.

The industry's challenge is to adopt more water-friendly technologies to dye cotton and polyester, the two most mass marketed textiles. So what can companies do to mitigate the effects of this timeless, yet toxic, dyeing process?

"There is no silver bullet," said Kathy Hattori, who runs a natural dye manufacturing company Botanical Colors. "There are so many ways to reduce the impact of textile dyeing," she continued, "because, for example, it's not realistic to eliminate a product such as polyester." Hattori explained many factories could start by tackling the wasteful dye-to-water ratio. A 1-to-30 ratio is common.

Reaching a 1-to-10 dye-to-water ratio is an accomplishment, Hattori explained, and when asked whether the manufacturer would then simply need more dye, she replied with an emphatic "you don't". Diluting a dye, she countered, simply means wasting more water: much of the answer in solving the waste involved in dyeing textiles lies in a factory's mechanisation. Various fabrics require different manufacturing processes, so one best technology does not exist for low-water or waterless dyeing.

Waterless dyeing should be the textile industry's holy grail, but widespread adoption is years away. In Hattori's view, polyester is the prime candidate because dyeing performs best in an airless environment with pressurised high heat, allowing dyes to disperse throughout the fabric. Colouring fabric using this waterless method could be feasible for polyester; natural fibres such as cotton and wool, however, can become damaged undergoing a similar process. Cotton comprises 45% of all fibres used within the global textile industry, so a sharp reduction in water consumption would be a huge process improvement for this sector.

One company taking on the textile sector's excessive consumption of water is ColorZen. Its process modifies cotton's molecular structure and allows dye to settle within the fibres without requiring the massive discharge of water, eliminating the need to rise off fixing agents that keep a fabric's colouring consistent. Compared to conventional processes, ColorZen claims its technology can finish cotton fabric using 90% less water and 75% less energy.

Another US firm, AirDye, insists its technology uses a sliver of the water and energy compared to traditional dyeing processes, and has several niche designers and manufacturers as customers. Instead of water, the company's technology uses air to disperse dye. AirDye's process embeds dye within textile fibres instead of merely on them, so colour lasts longer and is more resilient to chemicals and washings.

Other than nebulous talk about partnering with NGOs to reduce water consumption, few large companies currently consider new waterless or near-waterless technologies. One that does is Adidas. During a telephone conversation earlier this summer, Alexis Olans, a senior director of the company's sustainability programs, explained the challenges and successes of what Adidas brands its "DryDye" technology.

Instead of water, Adidas' supplier uses compressed and pressurised carbon dioxide as the agent to disperse dye within polyester fabric. The CO2, which takes on liquid-like properties, is contained in stainless steel chambers. After the dyeing cycle the CO2 becomes gasified, and dye within the cotton fibres condenses as it separates from the gas. The CO2 is then recycled and pumped back into the dyeing vessel. Adidas claims using CO2 is a safe and environmentally-friendly option because the gas is contained and can be used repeatedly without the risk of any emissions.

Although dyeing using compressed CO2 has existed for over 25 years, Adidas claims a supplier in Thailand operates the only factory with the ability to scale this technology. So can this process transform the textile industry? Not quite yet according to Christian Schumacher, an expert in textile dyes and chemicals, who points out that investment in such equipment is still costly.

Nevertheless, assumptions water is integral to dyeing are crumbling. As Olans says: "Do we really need water to dye? We discovered an answer that not only solved the intended goal, eliminating water, but also had multiple positive side effects, including a reduction in energy and chemicals."

Adidas' work is a step, but the recent announcement it would manufacture one million yards of waterless dyed fabric is still a relative drop in the ocean. And among large global brands and retailers, few have aggressively ventured into waterless dyeing technology. Levi's, for example, sells a line of jeansfinished using up to 96% less water than similar garments.

Nike and Ikea recently partnered with Netherlands-based DyeCoo, owners of the technology used to make Adidas' DryDye shirts, but have been quiet since that agreement. H&M touts its partnership with the charity WWF, but can its discussion of water, with talk about a "holistic strategy", commitments and partnerships move into real action? Why are the world's largest apparel companies not doing more?

The answer in part lies in Tirupur, India, home to scores of factories and workshops where workers dye materials for t-shirts and other garments marketed around the world. Local dye houses have long dumped wastewater into the local river, rendering groundwater undrinkable and local farmland ruined. Despite tougher regulations, a watchful local press, and the closure of companies in non-compliance, water pollution has festered. The city's 350,000 residents, not multinational textile companies, pay the price.

The global demand for cheap clothing will push dye houses to simply react to local regulations by moving operations to another city. Moral outrage will not convince many leading clothing manufacturers to change their ways; as long as companies do not pay a price for the land and water their suppliers poison, watch for the excessive use and abuse of water to dye clothing to continue.

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