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 created a face side dominated with indigo dyed warps and an undyed inside of wefts. The limited penetration of indigo dyes into warp yarns and subsequent washing techniques jointly create the distinctive worn-out appearance. Blue denim jeans have therefore represented true denim for over a century. In the last two decades, however, things have begun to change.
Cotton fibers endow denim with all of its features – softness, absorbency, breathability, durability, easy of care, versatility, and affordability. Originally, only cotton fibers were used in denim and many people still believe that true denim must be 100% cotton.
Tied to the single global cotton market, however, denim manufacturing was susceptible to large price fluctuations. To mitigate against this risk and reduce costs, the industry began blending synthetic fibers into the denim – polyester in the 1980s. This was followed by Spandex for elasticity, Tencel for silkiness and delicacy, and finally T400 for stretch.
Manufacturers have also started using other natural fibers to simulate the look of denim while maintaining its original features. For example, linen and wool are either blended with the cotton or used solely to make denim-looking products.
The fabric construction of denim has been enriched too. Increasingly, so-called knit denim has been adopted by designers because it offers greater stretch and more comfort, while keeping the indigo color and aged effect. Flexibility and slim fitting mean knit denim is primarily used in women’s and children’s products.
The color of denim is also changing. The dominance of indigo blue is being challenged by new types of dyestuff and dyeing methods, giving consumers the option to buy white, black and pastel colors.
Part of the appeal of denim is that it represents individuality, no small feat for globe’s most popular trouser. It is said, because of the variety of materials, dying methods and construction techniques, no two pairs of jeans are identical.
Impact on the Environment and Human Health
The popularity of jeans it is not without its costs. To get faded clothing, stone washing using pumice is often employed. This abrades and destroys the fabric’s surface to reveal the undyed white threads. Harsh chemicals are also used simultaneously or subsequently to decompose the indigo dyes. To get the distressed look, denim is subjected to chemical-intensive washes (up to 20 times).
The waste from these methods is often just dumped, meaning 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 pollute the local environment and local rivers.1
At the same time, denim factory workers often receive very little protection from these hazardous substances. This toxic environment is known to cause several health problems, including respiratory disease, hearing loss, skin cancer, and brain damage.
As the full cost of denim production and washing becomes clearer, authorities have begun to demand better working practices. Industry leaders have responded with innovative washing processes and technologies that bring sustainable solutions. From more efficient washing machines to eco-friendly chemicals, such as enzymes, various options are now being explored and implemented. The common goal is a reduction in water, chemical and energy consumption.
One alternative is ozone washing – harnessing the natural bleaching capabilities of ozone gas to give a range of specialty bleached effects with substantially reduced environmental impact. Ozone naturally has strong oxidizing capabilities, which can destroy indigo dyes on the fabric’s surface, creating a bleached appearance. Denim jeans are dampened and exposed to the ozone for the treatment, and the desired bleaching level can be achieved in around 15 minutes. The ozone reconverts to oxygen and is released safely into the environment. Dry ozone processes are now also available, removing the need for bleach and water, to create sustainable denim.
Another technique involves computerized infrared lasers. These can be used to create localized wear, whiskers, intricate patterns, and personalized designs without chemicals or water. It is precise, repeatable and flexible, and many high street brands are already employing such techniques to reduce their environmental impact.
Chemical companies are also innovating, creating more eco-friendly bleaching chemical formulas and alternative dyestuffs. For example, liquid sulfur dyes can achieve much higher fixation rates, over 90%, in comparison to traditional indigo dyes, usually less than 10%. This means 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 (20-30%), meaning less dyes and chemicals. Some technologies use nano-sized air bubbles instead of water to dye jeans, giving them both softness and wrinkle repellant properties. Reducing water means reductions in chemicals and energy.
Consumers are looking for sustainability from production to disposal. Many brands now recycle old jeans, turning them into building materials or new products. The planet’s adoration of the jean does not seem to be fading, it is therefore vital for retailers, brands and manufacturers to respond with safer and less harmful production methods.
SGS offers a comprehensive range of services to help manufacturers and brands deliver sustainable clothing products to their customers. With over 40 specialized laboratories around the world, we have the capabilities in place to help your business create safer products that comply with your target markets requirements.
For more information, please contact:
Min Zhu, Ph.D.
Consumer and Retail Services
US & Canada Softlines, Technical Director
SGS North America, Inc.
t: +1 (973) 461 1230