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Sophie Benson
Due to this use-pollute-return cycle, it’s thought that dyeing and finishing is responsible for more than 20% of global water pollution. Today, 90% of clothing is dyed synthetically, but not all dyes are created equal, so it’s crucial to know the right questions to ask.
Azo dyes are a popular commercial choice because they’re cheap, effective, and can be used at lower temperatures. However, some azo dyes are carcinogenic, as well as causing effects such as allergic reactions and endocrine disruption. They can also break down into aromatic amine compounds, which can harm humans and pollute water. As a result, the use of certain azo dyes is prohibited in the markets such as the EU and China, however they still represent the majority of dyes used for industrial purposes.
Pollution caused by dye has the greatest impact on low income producing nations. For instance, in China over 70% of rivers are polluted, while in Dhaka, Bangladesh, numerous rivers have been declared as "biologically dead" due to toxic wastewater. To cut costs, many factories simply release toxic post-production water back into local water streams. The treatment of wastewater is vital to tackle such pollution and initiatives such as PaCT, the ZDHC Roadmap to Zero Programme, and the bluesign SYSTEM are helping to enact industry-wide improvements.
Before synthetic dyes, there were natural dyes made from things like plants, berries, leaves, and flowers. Now they’re making a resurgence as the pollution from synthetics becomes clear, but they may come with drawbacks like heavy water usage, an inability to affix to synthetics, and a lack of colour fastness. However, a new generation of natural solutions made from fungi, Seaweed, Algae, and food waste are emerging which are more efficient and effective than ever before.
Mordants, (also called fixatives) which are used to bind dyes to fabrics include chromium and tin which can be dangerous to both the dyer and the environment. Even natural dyes often use synthetic, irritating, or even poisonous mordants, so it’s important to pay as much attention to mordants as you do to dyes. Alum is considered to be non-toxic, while a new era of bio-mordants are presenting a safer, more environmentally-aware future.
Given that so much dye pollution is caused by irresponsible wastewater practices, eliminating the use of water in the first place makes perfect sense, and now that’s a reality. Innovations like Endeavour Waterless Smart Dyeing, DryDye, and DyeCoo make use of supercritical fluid and digital technology to enable uniform, vibrant dyeing without the use of water. A further advantage of waterless dyeing is a reduction in energy use as the fabrics don’t need to be dried.
Sages makes natural dyes from food waste sourced within a 15-kilometre radius of London, where the company is based. Ingredients, which come from supermarkets, farms, and food processing plants, include beetroot, cabbage, blueberries, and avocado skins. The pigments can be integrated into existing dyeing processes, and any water used during the process remains uncontaminated and can be used over and over again.
Sages currently has 12 colours in its line-up and another 30 in production. It also claims to have created an environmentally-friendly mordant, complimenting the natural, non-toxic nature of its dyes. The patent pending dyes are set to launch commercially in the near future.