A WATER DIET FOR DENIM January 17, 2017 – Posted in: Sustainability
It is no secret that the textile industry and more specifically the denim industry weighs a considerable water blue print on the planet. Your average pair of jeans necessitates a total volume of 2.900 Gallons of water (approx. 11.000 liters). Heavy indeed. According to the World Bank, it alone will account for 17-20% of the world’s water pollution. Luckily, manufacturers are turning to a myriad of new, more sustainable manufacturing processes. These involve recycled fibers, enzymes, ozoning, and new dyeing methods. Hopefully these should allow our respectful pairs of jeans to go on a much needed water diet.
In the aforementioned 11.000 liters, an estimated 40-50 per cent is needed for the plant’s growth, namely cotton. To obtain cotton with the lowest cost of resources some denim brands such as Levi Strauss, American Eagle Outfitters, Gap have turned to BCI (Better Cotton Initiative) a non-profit organization that strives for a more efficient use of water.
The remaining 5.000 liters of water are used for the manufacturing steps, from fiber spinning to the final garment treatments and finishings, giving birth to that washed out look so sought after in latest jeans’ fashion. Although quantitatively less important, it is however these critical steps of the processes that giving denim its unique look, (namely pre-treatment, dyeing, and finishing of the fibers) that are the most detrimental to the environment. These account for 20 percent of industrial pollution according to the World Bank. So what technology is being put forward to revolutionize these specific processes?
The use of recycled fibres or the implementation of artificial fibres from natural polymers are gaining acceptance by denim brands and end consumers. The same is occurring with the methods for obtaining the final effects that make jeans so special. The use of a new generation of clever enzymes is replacing the traditional stone-wash or sand-blasting wash-down techniques which use a lot of water and energy. At the same time, treatments with ozone and laser beams are being employed instead of chemicals like sodium hypochlorite or potassium permanganate to achieve both water savings and prevent the contamination of effluents with hazardous chemicals. These enzymes are used to treat and modify fibers, particularly during textile processing and in caring for textiles afterwards. They enhance the preparation of cotton for weaving, reduce impurities, minimize “pulls” in fabric, or as pre-treatment before dying to reduce rinsing time and improve color quality.
When facing last year’s draught in California, a number of big names have adopted new technology for washing: ozoning. This process consists in replacing water with ozone during the washing process. A machine sucks in and filters ambient air. The resulting oxygen obtained is purified and enriched to become ozone, which is in turn injected into the drum containing the jeans. Like sunlight, the gas naturally ages the denim fabric. This process uses 50% less water than traditional washing.
Nevertheless, the remaining step: dyeing, which is crucial to acquiring the desired depth, cast and final contrast effects, is still mainly based on traditional dyeing technologies involving the use of Indigo and associated chemicals such as Sodium Hydrosulphite. As shown in practical analyses conducted by Clariant in many different countries, the total volume of water required for dyeing and removing of unfixed dyestuff requires volumes of water between 15-25 l/Kg dyes CO warp in a slasher denim range as reported on engineer live.
Luckily a new dyeing process, the DyeCoo process dyes polyester without water, chemical additives or drying. It pressurizes carbon dioxide (CO2) to the right temperature to turn it into liquid and gas. This “fixes” the colours of the fabric. As proof of the promise of this solution, the global sportswear giant Nike is now a shareholder in DyeCoo, whose R&D teams are now developing similar technology for nylon and cotton, according to Suezenvirnoment.com.
Here is to lighter jeans! Cheers!