Consumers are increasingly looking for sustainability in their clothing choices. Unfortunately, the world’s most ubiquitous clothing article, the denim jean, is also one that has traditionally had major negative impacts on the environment. Clothing manufacturers and retailers are now looking at ways to reduce its impact.
Invented in California in 1873, the denim jean was originally manufactured using denim or dungaree cloth, a type of pure cotton 3/1 twill woven fabric with indigo dyed warp yarns and undyed weft. This meant the face side was dominated by indigo dyed warps, with an underside of undyed wefts. This effect, when combined with different washing techniques, has helped create the distinctive worn-out appearance.
Many people believe true denim must be 100 percent cotton. It is cotton that gives denim its softness, absorbency, breathability, durability, easy of care, versatility, and affordability. Being tied to a single cotton market meant, however, that manufacturers were susceptible to large price fluctuations. Manufacturers have therefore started mixing in other synthetic fibers to give different characteristics and reduce costs — polyester in the 1980s, then Spandex for elasticity, Tencel for silkiness and delicacy, and T400 for stretch. Manufacturers have also started incorporating other natural fibers — linen and wool.
Manufacturers have also altered the fabric construction of denim, often using so-called knit denim. It has more stretch and is more comfort but maintains the indigo color and aged effect. This is often used in women’s and children’s clothing for flexibility and slim fitting.
The popularity and variety of jeans, including different colors, has had a major impact on the environment. For example, fading often requires pumice stone washing with harsh chemicals that simultaneously or subsequently decompose the indigo dyes, and the distressed look may require up to 20 chemical-intensive washes.
The waste from these methods is often just dumped into rivers. Chemical residues, heavy metals (manganese, cadmium, chromium, mercury, lead and copper), strong bleaching and oxidizing agents, blue pigment dust, fine particles of pumice, and destroyed fibers are therefore a major problem for the local environment.
Work practices are also often not designed to protect employees. The toxic environment surrounding denim production is known to cause several health problems, including respiratory disease, hearing loss, skin cancer, and brain damage.
Authorities are now demanding better working practices and industry leaders are responding. Innovative washing processes and technologies are creating sustainable solutions. More efficient washing machines and eco-friendly chemicals, such as enzymes, are among the options now being explored and implemented. The common goal is a reduction in water, chemical and energy consumption.
Ozone washing is growing in popularity — harnessing the natural bleaching capabilities of ozone gas to give a range of specialty bleached effects while substantially reducing the impact on the environment. Ozone has naturally strong oxidizing capabilities, which can destroy indigo dyes on the fabric’s surface, creating a bleached appearance. The process involves dampening the denim jeans and then exposing them to the ozone. It can achieve a desired level of bleaching in about 15 minutes. The ozone then reconverts to oxygen and is released safely into the environment. Dry ozone processes are also available, removing the need for bleach and water. This will create sustainable denim.
Manufacturers are also using computerized infrared lasers to create localized wear, whiskers, intricate patterns, and personalized designs without chemicals or water. This method offers precision, repeatability and flexibility.
The chemicals being used are also changing. More eco-friendly bleaching chemical formulas and alternative dyestuffs mean less impact on the environment. For example, liquid sulfur dyes can achieve much higher fixation rates, more than 90 percent, in comparison to traditional indigo dyes, usually less than 10 percent, meaning far lower dyestuff discharge. They also have excellent washing-off and wet-fastness properties.
Other options include foam dyeing and finishing, which reduces the wet-pick-up rate significantly (20 percent to 30 percent), meaning fewer dyes and chemicals. Manufacturers are also using nano-sized air bubbles instead of water to dye jeans, giving them both softness and wrinkle-repellent properties. Reducing water means reductions in chemicals and energy.
These are just some of the ways the denim jean industry is adapting to changing regulations and the increasing demand from consumers for more sustainable products.
Min Zhu, Ph.D., is Consumer and Retail Services, US & Canada Softlines, Technical Director, SGS North America, Inc.
SGS has a worldwide network of more than 40 state-of-the-art laboratories specializing in softline testing. Its team is drawn from multi-disciplinary backgrounds, allowing them to carry out a comprehensive range of physical, chemical and functional testing services for components, materials and finished products. SGS helps companies ensure quality, performance and compliance with international, industrial and regulatory standards worldwide. Learn more about SGS’s Softlines Services.