“Less of this” and “less of that” is all we see as the industry moves the needle on environmental design. But what about thinking from a “more of this” perspective? Yes to more regenerative, circular design, yes to natural fibers and processes and yes to more natural dyes. As we move into the era of the informed, engaged consumer, an increased interest in natural indigo has emerged. But how do we scale this precious and unpredictable dye-stuff from artisanal specialty brands to mass production?

Our sustainability advocate and writer, Ani Wells spoke to Celia Geraedts of Blue Print Amsterdam, Kakuo Kaji of BUAISOU, and a few of the world’s leading denim mills to see how natural indigo can play a part in our current denim production system and how we can see more of it in our industry.

Before we look at what the future holds for natural indigo, we have to look to the past. Indigo is one of the oldest dyes in the world, with the first indigo-dyed fabric found in Peru dating back 6200 years! I like to think of what the Peruvians thought when they discovered the Indigofera Tinctoria plant.

Us denim heads would agree on how magical indigo really is and remember the first time we saw the oxidisation process, so imagine how incredible it would have been to discover it! But how did indigo become synonymous with denim? We asked Mohsin Sajid, founder of Denim History to give us the lowdown.

Blue Print Amsterdam flags

In 1498, Italian Vasco de Gama discovered a sea route that connected India and Europe, introducing Indian Indigo to Europeans. So naturally, denim fabric emerged from Europe, specifically in both the cities of Nimes, France and Genoa, Italy. “Serge de Nimes” was a woad-dyed twill that was first made of wool, then mixed with cotton and hemp which became “de-nim,” while in Genoa a fabric with an indigo dyed warp and white weft was worn by sailors and eventually adopted the name “Genes.” Indigo became synonymous with workwear and popularised from the 15th to 17th Centuries. and in 1873, Levi’s Strauss and Jacob Davis patented the rivet. These early Levi’s garments were actually made from Brown Duck Canvas, soon after, Levi’s started to use Natural Indigo in their production of waist overalls.

Then came synthetic indigo and swooped up the entire indigo market. Synthetic indigo was first introduced in 1883 by German chemist Adolf von Baeyer to counter the British who were controlling the export of indigo from India. This invention paved the way for the first industrial mass production of synthetic indigo in 1897. But, it wasn’t until Karl Heumann that the world capitalized on this discovery. Seven years later, large quantities of synthetic indigo began to flood the market. Made from anthranilic acid, the synthetic colourant is chemically identical to natural indigo and has almost entirely replaced the natural dyestuff.

Let’s take a closer look at Levi’s journey to pinpoint when the switch was made: Levi’s first denim producer, Amoskeag Manufacturing Company in Manchester, New Hampshire used natural indigo imported from Indus valley, AKA modern-day Pakistan. But from around 1915, Levi’s started switching to Cone Mills, who used synthetic indigo, and from 1922 used exclusively Cone fabric. All synthetic. Natural Indigo was reintroduced in denim production when Japan started to produce their own denim, starting from 1972 onwards and Levi’s officially started with natural Indigo again with the introduction of the iconic 1st Levi’s Red collection from 1999 and special collections after that. 

Levi's RED, 1999. Hemp denim dyed with natural indigo.
©︎ Kyoko Nishimoto / BUAISOU. Carefully monitors the dye process.

But in 2010, the global production of synthetic indigo was 180 million pounds, representing about 15% of global dye production for cotton! And today, less than 1% of indigo dyes used are derived from the Indigofera plant because of the inconsistencies with the resulting colour and the need to pump out precise replicas of a single product.

So, how is that 1% of natural indigo being used today? 

The number of pieces a brand produces directly correlates with the type of dye used because of various factors: brands producing on a mass scale generally don’t have the margins or time to perfect their product, whereas artisanal and specialty brands really put the time and energy into making something special. 

©︎ Kyoko Nishimoto / BUAISOU
Tenue de Nimes X The Blue Print Amsterdam

For makers and artisans like Kakuo Kaji, founder of BUAISOU and Celia Geraedts, founder of Blue Print Amsterdam, there is absolutely no question when choosing to work with natural indigo. The depth of “vibrating blue hues,” as Celia calls it, is something that can’t be replicated with synthetic dyes. Being able to touch the material during the dyeing process allows Celia to act fast to correct folds and adjust quickly to achieve even and qualitative results; something that brands solely focused on mass product and maintaining profit margins, aren’t able to do.  

Celia Geraedts of Blue Print Amsterdam.
©︎ Kyoko Nishimoto / BUAISOU: Kakuo's note shows a record of the life of an indigo dye vat

Aside from natural indigo’s aesthetic and environmental benefits, there are many health benefits, as well! Natural Indigo as a means of wellness? We’re here for it.

Celia’s house was recently taken over by mosquitoes, but her studio, with its constant natural indigo vat running? Zero mosquitos in sight. Its antiseptic properties have many benefits (like mosquito repellency!), but one of the most interesting is as a treatment for burns. After applying natural indigo to a burn, Celia noticed the stinging sensation immediately disappeared and the healing process was considerably faster.

A true testament to our favourite hue is Celia’s perfect health over the past ten years since working with indigo with her bare hands. But, it isn’t so strange that this dye has so many healthy benefits; out of all the Indigofera types, only 10 out of 200 are used for dyeing! Many of the others are used for medicinal purposes, like treating wounds and illnesses. In one of Celia’s workshops, it was noted that indigo tea was the answer to someone feeling under the weather (sadly the tea is not blue!)

Natural Indigo Vat at Blue Print Amsterdam

The above says a lot about using natural indigo, but keeping the craft and the knowledge alive whilst exploring new ways of applying it, is also just as important. It is an ever-evolving journey working with such a magical dyestuff, and after years of working with it, there is still an incredible amount to learn. For Kakuo Kaji, indigo has been a part of his culture for centuries. “It is a purist art form and I am glad to play a part in continuing this tradition.” Mastering the process is transcendent for indigo artisans. It gives life to indigo dyers, which you can see by the way Celia cares for her 50, 120, and 400-litre indigo vats every day, even when on holidays! The process is the beauty of natural indigo and why Celia believes natural indigo should remain a luxury product. 

Growing the indigo plant is also not to be underestimated, in fact it takes the same amount of time to grow a baby! Because of all of the time and work that goes into growing and harvesting, it makes sense that these products do not come cheap and should be treated with respect. 

“In comparison to synthetic dyes, the labor involved in indigo farming, dyeing, and production must be compensated fairly for the effort. And this way of thinking is probably one of the reasons why synthetic indigo was created.”

— Kakuo Kaji, Founder of BUAISOU

©︎ Kyoko Nishimoto / BUAISOU
Persicaria Tinctoria ©︎ Kyoko Nishimoto / BUAISOU

Anytime you are working with a natural agricultural product, there will be uncontrollable variations due to factors like weather, crop variation and harvesting. One of natural indigo’s main obstacles to mass production is achieving consistent dye results without the use of a bunch of chemicals that help the natural dyestuff adhere to yarn, and as Candiani explains, this is where most of the work goes. But, Candiani has been working on breaking the natural indigo code for two years and it’s still a work in progress! Sourcing high quality natural indigo that fulfills their CSR requirements and sustainability policies has not been an easy task.

Stony Creek Colors X Cone

Sarah Bellos, founder of Stony Creek Colors, notes significant adulteration in natural indigo supply chains. Brands/mills/home dyers think they are buying natural indigo when it is actually synthetic. So, for the folks who can’t grow their own product, there are analysis methods to discern whether people are using the real thing or synthetic.

Stony Creek is on a mission to see natural indigo represented in the market and work with mills to provide easy-to-implement solutions. They have built several innovations into the dye production process to minimize the batch-to-batch variation that’s typical with natural dyes. These include uniform seed varieties, mechanical harvesting systems, standardization in its extraction process forming the indigo, and batch blending to standard formulation sizes based on a target indigotin value. Sarah explains, “Each time an order is placed, each batch is blended to an exact purity of indigotin (the active dye chemical in indigo). This process allows for consistent dyeing and also minimizes any naturally occurring variation between lots.” 

Cone Denim states that “working with natural indigo is really no different than working with cotton. Cotton has a lot more variation than a man-made fiber like polyester. Polyester is produced in a controlled environment with controlled humidity, temperature, etc. Natural vs Synthetic Indigo is the same comparison.” With this in mind, Cone Denim has developed a strategic process that achieves greater consistency from bigger lot sizes and blending batches to minimize inconsistencies. Cone Denim’s strategic partnership with Stony Creek Colors has also been vital in scaling their natural indigo lines.

Clearly, with the right focus, indigo consistency is achievable, and in Bossa Denim‘s eight years of experience working with natural indigo, there have been no issues with any colour continuity problems, meaning no disadvantage to the customer when producing higher volumes. Bossa can achieve that deep, bright, magical blue we love in terms of the actual colour! Not to mention, natural indigo products work well with sustainable washing methods like lasers and ozone, according to Bossa, Cone Denim and Stony Creek. Cone recently launched a new, deeper natural indigo shade that allows you to achieve a full range of washes adding to its flexibility and commercial viability. Stony Creek also added that the dyeing process seems to influence the wash down more than the indigo source itself, meaning no limitations or adjustments are needed in the wash process!

Cone Denim dyed using natural indigo.
Stony Creek Colors natural indigo.

So, based on the research Bossa, Candiani, Cone Denim and Stony Creek Colors have done, it seems entirely possible that natural indigo can produce our desired looks and qualities for larger quantities. But the question still stands: is it a viable replacement for synthetic indigo altogether, or will it remain a luxury product for SMEs and artisanal brands? 

When Cone Denim and Stony Creek Colors began their partnership, scalability was a critical conversation from the beginning. From a manufacturing standpoint, natural indigo is scalable, limited only by supply availability. For indigo producer Stony Creek, many of their initial customers were artisanal brands like Tellason or Gustin. Still, they believe there is a compelling opportunity for mass-market brands to adopt Stony Creek’s plant-based indigo and have seen more starting to make the transition. 

"Something can be plant-based and still industrial. Industrial doesn't have to be a bad thing, especially if it helps make it available to a wider range of customers. A lot of the innovations we invest in developing can help larger known brands reach their corporate sustainability goals from right within their own supply chain. We've spent a lot of time figuring out: how do we reclaim our wastewater and use it again? How do we actually quantify how much carbon we're sequestering through our waste biomass composting processes? All these are things that, when you can implement them across a large scale, are really exciting, instead of keeping it artisan for the sake of it." 

— Sarah Bellos, Stony Creek Colors

Fibershed, a non-profit organization that develops regional and regenerative fiber systems, has done extensive research and testing to make a case for scaling natural indigo based on the water extraction and compost systems for production. If you have heard of the traditional Japanese method “sukumo,” this is the composting method! Break it down a bit further, and the steps in sukumo include harvesting, drying the plants, separating the leaves, and tending compost for approximately three months. If it sounds like a lot of love and care to you, rest assured it is! Unlike the water extraction system, the compost system is highly labour intensive and does not get more efficient with quantity. A concept the fashion and denim industry isn’t so familiar with. But aside from the labour needed, we need to consider the land required.

Golden hour at Stony Creek Colors indigo farm in Tennesse.

Looking from a global perspective, Fibershed estimates that replacing global synthetic indigo production with natural indigo from the composting process would require about 2.1 million acres of indigo or about 3300 square miles of production. That’s almost 2 million football fields put together! And we know the price isn’t small either. The cost of natural indigo would be more than 80 times that of synthetic indigo. Not too appealing for the masses looking to crunch numbers. “The major factor is really cost, and propaganda from petrochemical companies; the producers of synthetic indigo. This is the reason why chemical indigo will most likely remain popular for the foreseeable future,” says Mohsin Sajid. Cone added that price limits the markets that can take advantage of the product, but is convinced that as natural indigo scales up and volume increases, thanks to companies like Stony Creek Colors, the economies of scale will kick in and will be more accessible at a wider variety of price points. 

So, the verdict? It seems very unlikely that natural indigo will be our saving grace as a one-to-one replacement for synthetic indigo, considering the priorities of scale, efficiency and margins for the majority of brands. Natural indigo will remain elusive and unique, which might be exactly what it was intended for. And with that being said, the goal might not be to replace synthetic indigo altogether but to see more natural indigo on the market, preserving its craft, natural beauty, and supporting local production.

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Sustainable denim advocate, educator and curator