In fashion, colour is a style statement. But it comes at an environmental cost.

Bright patterns, eye-catching hues and even all-black ensembles typically require energy- and chemical-intensive processes to ensure colours bind to fabrics and stay strong for a garment’s full lifecycle.

Pressure from environmental advocates has pushed big brands to take steps to weed out some of the industry’s most harmful chemicals. But the dyeing process itself remains largely unchanged. Dyeing machines still typically use large volumes of water and energy, often relying on dirty sources like coal. Dyes are still mostly made from harsh synthetic chemicals.

Finding solutions to these challenges has attracted some funding from investors focused on developing more sustainable ways of operating within the industry, but not nearly as much as buzzy areas like next-gen materials or resale.

That’s beginning to change thanks to the increasing maturity of innovative solutions and growing awareness of just how big a proportion of the industry’s overall impact sits in this part of the supply chain; a report published last year found producing, dyeing and processing textiles accounts for 52 percent of overall supply chain carbon emissions.

That “was really a wake up call,” said Jana van den Bergen, innovation associate at Fashion For Good, an incubator for start-ups focused on developing more sustainable solutions for the fashion industry. “People were already looking at processing technologies, but everyone [realised they] should double down on their efforts.”

Below, BoF unpacks some of the most promising innovations gaining the support of high-profile industry backers.

Next-Gen Natural Dye

One of the biggest impacts of fabric dyeing is the chemical pollution it leaves behind.

Though natural dyes derived from plants and insects have existed since humanity started colouring cloth, these can still require polluting processes to adhere to fabric. Establishing sources that are abundant, cost-effective, high-performance, and not in competition with other sectors, like food and agriculture, is also a challenge.

A crop of biotech start-ups have found ways to re-engineer nature as a workaround to some of these issues.

Last month, UK-based Colorifix secured £18 million ($22.5 million) to scale up its biotech dyeing technology. The company uses DNA sequencing to replicate colours that appear in nature, genetically modifying bacteria to “grow” a dye in the chosen shade. The technology replaces the need for synthetic chemicals and also requires less water and emissions than traditional dyestuff, Colorifix says.

While, at present, the company only has six colours on the market, it’s worked with brands including Pangaia and H&M Group (whose venture arm also led its recent funding round). It’s in talks with around 120 more companies keen to work with its dyes, chief executive Orr Yarkoni said.

Other companies in the space include French microbe-based dye producer Pili, which recently received a €400,000 ($418,588) grant from the European Commission to pilot a project aimed at turning organic waste into bio-based dye and chemical solutions for the apparel and textiles industry.

However, at present, the scale of such technologies and the colours they can produce are very limited. Colorifix is currently working to bring 24 more colours to market, but new shades beyond those already in development need to be created from scratch.

For now, one of the biggest challenges is recreating an absence of colour: black.

Low-Waste Dyeing

Emerging technologies focused on waterless dyeing offer a potential game-changing solution for a thirsty part of fashion’s supply chain.

Fashion For Good is backing a consortium of eight companies developing lower-impact, mostly waterless dyestuff and processes. Technologies range from foam-based dye to a technique that uses vessels of highly pressurised carbon dioxide as a solvent for dye instead of water.

Among the most mature innovators involved are UK-based Alchemie and Sweden-based Imogo, whose “digital spray” technologies apply just the right amount of dye substance to a fabric to achieve the desired colour, not dissimilar to the workings of an inkjet printer.

Imogo already has a pilot machine in operation at a dyehouse in Sweden, and is working with cellulosic fibre maker Spinnova. The first fabrics dyed with its technology will hit the market later this year. It will expand further next year, when one of its machines will go into operation in a knit garment manufacturer in Bangladesh.

Encouraging more manufacturers to invest time and money to adopt the technology is one of the biggest challenges facing the company as it looks to scale.

An Imogo machine can cost up to €600,000, but founding partner Per Stenflo is hoping to convince the industry that efficiency gains will make up for the upfront cost. The machinery is compatible with conventional dyestuff and can colour fabric at up 50 metres a minute. It’s also self-cleaning and can switch between shades in 10-25 minutes, he said.

Recycled Pigment

Textile recycling technologies that can turn old clothes and fabric scraps into new materials are among the sustainable innovations that have captured the greatest interest from the fashion industry. But some material scientists want to see the colours from old clothes recycled too.

“It seems like the next natural step to take after we recycle the fibre: let’s talk about chemical circularity as well,“ said Aida Rafat, co-founder and chief executive of DyeRecycle, which uses non-toxic chemistry to strip textiles of their dyes to create reusable dye solvent.

The company was one of eight selected earlier this year for Fashion for Good’s competitive innovation programme (a separate project to its dye-specific consortium). Though still in prototype stage, DyeRecycle’s process could reduce the need to develop new dye solutions at all. And as textile-to-textile recycling gains traction, Rafat sees an opportunity to reduce the environmental footprint of recycling plants, which she says have struggled to develop their own processes for de-colouring feedstock without using harsh chemicals and bleach.

The company is preparing to test its technology at a more commercial level this summer.

Dope Solutions

Not all solutions to clean up dyeing are fresh from the lab. Dope dyeing, also known as solution dyeing, is a well-established practice borrowed from the plastics industry that can be found in the products of brands ranging from Ikea to Gymshark.

Rather than soaking textiles in large vats of hot water and chemicals, material suppliers inject colour into materials that are liquid polymers before they become solid fibres, like polyester and cellulosics made from plant-based pulp. The result is a much smaller water, chemical and carbon footprint. It’s a process that some cellulosic fibre companies — like Spinnova and Tencel producer Lenzing — and textile recyclers are looking to incorporate more into their production.

But there are basic challenges to widespread adoption; the technique is more expensive than conventionally dyed textiles and needs to be produced in very large batches. The resulting high order minimums and requirement to make decisions about colour at a much earlier stage of the supply chain can make it less attractive to design and buying teams.

Ultimately, evolution instead of revolution may be the answer to scaling better dye solutions. Some suppliers looking to embrace innovation are installing new machines next to their old ones, said Fashion for Good’s van den Bergen, allowing them to increase or maintain production capacity and therefore make the investment less risky. When older equipment inevitably does give out, they’re open to replacing it with newer innovations.

What still needs to change is how much the industry funds this innovation to begin with. “Demand is often not the issue; a lot of people are interested,” van den Bergen said. “It’s now [about] ... equipping the innovators to actually fulfil that demand.”