Sustainability In Denim
Even the average jeans customer knows already that denim belongs to the bad guys concerning sustainable issues. Our industry consumes lots of water, uses hazardous chemicals and with all the super stretch types of denim, we contribute to microplastic pollution.
But the awareness is raising, new possibilities were developed over the past years and there are many ecological materials and treatments available already today.
In this series, we take a look at the impact of denim and jeans, but we put focus on the progress of sustainable alternatives.
The time when sustainable decisions came with limited possibilities in design and outcome is a thing of the past!
No. 4: Sustainable denim alternatives to conventional stone wash
In the last episode, we learned about new technologies that save lots of water and chemicals by dyeing cotton yarn in indigo blue. In case you missed it, read it here.
Today we take a look into the popular stone wash process: how it works, what it does to the jean and to the environment, and how we can create similar effects and do less harm to the people and the planet.
As shown in our last episode, the denim fabric is dyed with the special pigment indigo. ‘Special’ because of two main properties: the need to be particularly treated to become water-soluble and the idiosyncrasy to be non-permanent. That means, indigo fades. You can experience that when you wear a new dark blue jeans; the blue pigments fade to your sneakers, to your fingers, and to a white shirt if you tack it in.
At first glance, this property seems annoying, but it is essential to create authentic used effects. Indigo pigments stay superficial and are not firmly connected to the yarn, hence they can be removed via abrasion. That means treated parts become lighter. The most popular process of partially removing indigo is stone wash.
The raw jeans are washed in a huge industrial washing machine together with pumice stones. These stones have a surface, comparable to sandpaper. As the machine rotates, the stones randomly take away some indigo from the jeans. Nice high- low contrast looks are created, especially at the seams, while the whole base color gets lighter as well. The intensity of the outcome depends on duration, the number of stones, and added chemicals.
Vintage Lee hangtags from the 1980s highlighting the conventional stone wash technique.
The Ecological Issues Of Washing With Pumice Stones
In general, this technique is working quite well, but it has some ecological issues:
The first problem with pumice stones is that they wear down super-fast. After 60 minutes of washing, they are basically half the size. That means, for every second washing load, new pumice stones are needed. Their mining, processing, and transportation come with high energy consumption.
The second problem is that the stones disintegrate into so-called “sludge”. That is a kind of mud, fully soaked with indigo and chemicals from the washing process. This sludge is hazardous waste and needs to be disposed in an appropriate way.
So, the side effect of a nice high-contrast stone wash is toxic sludge and lots of wasted energy.
What can be done to eliminate both problems? Are there alternative materials, which can stand many, many more washing processes?
The picture shows artificial stones.
The picture shows dried sludge (waste from conventional stone wash).
The picture shows conventional pumice stones, fresh (left) and after 1 hour of stone wash (right).
Other New Technologies
New artificial stones, created from ceramics, clay, or even synthetic materials can do the same job as pumice stones but have a much higher lifespan. Some of them can do up to 100 washing processes (instead of two!). So besides avoiding toxic sludge, they also save transportation and acquisition costs.
Another technology eliminates the need to add stones completely, by replacing them with sandpaper which is attached directly to the drum of the washing machine. In this case, the washing machine itself is used as the abrasion surface to create the required effects. These special coverings for the drums come in different abrasion levels, so the required effects can be fine-tuned.
Both methods of avoiding pumice stones are great replacements for the conventional way of treating jeans to become artificially used.
Many washing houses already work with at least one of those sustainable methods. But according to my experience, the use of those technologies needs to be particularly requested. In general, communication between the designer and the wash developer is a prerequisite to creating beautiful garments with the smallest environmental impact possible.
Images of the NoStone machine by Tonello with the outcome on a pair of jeans. NoStone eliminates the need for pumice stone, is reusable, installable on existing Tonello machines, and its latest version is more durable. It also zeroes out the emissions associated with the procurement of pumice stone, i.e. its extraction, transport and processing. NoStone achieves the same taste as traditional stone-wash with less water, as it allows you to skip all the rinses needed at the end of the process to remove the sand/dust from the garment.
Learn more about sustainable denim!
- No. 1: Sustainable fibers for denim, why hemp attracts more and more attention.
- No. 2: Recycling in denim, how we could minimize the impact of farming.
- No. 3: Waterless indigo dyeing, how we can reduce water use.
Stay tuned for more sustainable alternatives in the denim world!
