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WHAT IS DYEING? 

The vibrant world of fashion and textiles is undergoing a radical transformation, driven by an urgent need for sustainability. Traditional dyeing processes, while effective in producing vivid colours and intricate patterns, have long been marred by significant environmental drawbacks, including excessive water consumption and pollution. Currently, 29% of the fashion industry’s carbon emissions come from wet processing, yarn and fabric preparation stages, which also use massive amounts of water. This sector presents significant opportunities to reduce emissions and water use through improvements in material processing. One of the key drivers for this change is the shift from wet to mostly dry processing, which can almost eliminate water use and consume less energy. 

Fashion for Good innovators have demonstrated potential reductions in water use, including savings of up to 83% in pre-treatment and 95% in dyeing. As the industry pivots towards alternative practices, innovative technologies are emerging, promising to revolutionise colouration in textiles. 

Dyeing and printing are the cornerstones of textile colouration, each serving distinct yet complementary roles. Dyeing is the process of uniformly applying colour to textile materials, such as fibres, yarns, and fabrics, typically using dyes that chemically bond with the substrate. Printing, on the other hand, is the precise application of colour in patterns and designs on fabric surfaces, often using pigments that adhere to the material’s surface through a binder. Both techniques are essential for achieving the desired aesthetic and functional properties in textile products.

STEP-BY-STEP JOURNEY THROUGH DYEING AND PRINTING

The journey of transforming raw textiles into vibrant fabrics begins with meticulous preparation and pretreatment. Before textiles can be dyed or printed, they must undergo several pretreatment steps to ensure they are clean and capable of absorbing colour uniformly. For cotton, these steps include 1) scouring, which removes natural oils, waxes, and impurities from the fabric, 2) bleaching to enhance the whiteness of the fabric, and 3) mercerising, which treats cotton with caustic soda to increase its lustre and dye uptake.

The dyeing process itself immerses textiles in a dye solution, allowing the colour to penetrate the fibres. Depending on the desired outcome, various dyeing methods are employed. The most prevalent method, known as exhaust dyeing, involves submerging textiles in large vessels where the dye solution circulates around the material. Another widely used method is cold pad batch dyeing, where textiles are impregnated with dye solutions and then allowed to react at ambient temperatures for an extended duration of around 18 to 24 hours. This method is particularly noted for its efficiency and reduced energy consumption compared to dyeing processes under traditionally high temperatures.

Textile printing, which adds designs and patterns onto fabrics, employs various techniques to achieve its effects. Screen printing uses stencils to apply colour in defined patterns, transfer printing transfers designs from paper to fabric using heat, and digital printing utilises inkjet technology for high-precision designs.

After dyeing or printing, the colour must be fixed to the fabric to ensure longevity and resistance to washing and wear. This fixation is typically achieved through heat or chemical treatments. Traditionally, the wash-off stage, which removes any unfixed dyestuffs, is water-intensive. However, recent innovations are significantly reducing the environmental impact of this stage by minimising water use and optimising the efficiency of the dye fixation process.

INNOVATIVE TECHNOLOGIES: A REVOLUTION IN DYEING

DYESTUFF:

The textile industry is at the forefront of a revolution, with several innovative technologies significantly reducing environmental footprints. 

• Colorifix uses genetically modified microbes to produce and fix dyes onto textiles. This bio-based approach leverages natural processes to create vibrant colours while minimising chemical use and environmental impact.
• Nature Coatings transform wood waste into high-performing and cost-competitive black pigments, and are a direct replacement for petroleum-based carbon black pigments. Their pigments do not contain toxic substances, known as PAHs, and are manufactured in a closed-loop system that emits negligible amounts of CO2 or other GHGs.
• Living Ink transforms waste microalgae into bio-based pigments, offering an alternative to petroleum-derived pigments. Their algae-based pigments have less environmental impact but also provide vibrant, UV-stable colours suitable for screen printing applications.

MACHINERY INNOVATIONS

• GRINP (pre-treatment): GRINP develops and produces machines to perform pretreatment using their plasma technology.  
• NTX Cooltrans technology employs a digitally enabled gravure printing method for both artwork and block colours. This innovative process is different from usual screen printing, using proprietary inks that comply with environmental standards.
• Companies like Alchemie and imogo have pioneered digital spray dyeing, which uses digital precision to apply dyes and finishing chemicals directly onto fabrics. This method uses significantly less water and chemicals compared to traditional dye baths and allows for precise control over colour application.
• Deven Supercriticals has developed a dyeing technology using supercritical CO2. They offer efficient single-step dyeing for man-made, natural and blended textiles.

ADDRESSING THE ENERGY CHALLENGE IN DYEING

One of the most significant challenges in textile dyeing is the high energy consumption, primarily due to the need to heat large volumes of water. To tackle this, two main strategies can be employed.

First, reducing the time required for dyeing processes can significantly lower energy usage. This can be achieved by optimising dye formulations and improving process efficiency.

Second, adopting waterless dyeing technologies, such as Deven Supercriticals’ CO2 dyeing, eliminates the need to heat water, further cutting down energy consumption. These approaches, combined with continued innovation, hold the promise of making textile dyeing more energy-efficient with less environmental impact.

A BRIGHTER FUTURE FOR TEXTILES

The textile industry’s journey towards sustainability is marked by groundbreaking innovations in dyeing and printing technologies. By embracing these advancements, the industry can significantly reduce its environmental impact while maintaining the quality and vibrancy of its products. 

From microbial dyes to digital spray dyeing, these technologies are setting new standards for sustainability, paving the way for a future in fashion. As the industry continues to innovate and collaborate, the promise of better textiles becomes increasingly attainable, offering hope for a more sustainable and colourful world.

^{1 McKinsey. Fashion on Climate: How the industry can urgently act to reduce its greenhouse gas emissions, 2020. https://www.mckinsey.com/~/media/mckinsey/industries/retail/our%20insights/fashion%20on%20climate/fashion-on-climate-full-report.pdf.} 

^{2 Fashion for Good. Fashion for Good Launches D(R)YE Factory of the Future, 2022. https://fashionforgood.com/our_news/fashion-for-good-launches-drye-factory-of-the-future-project-%E2%80%8E/}