Researchers have developed a new polyester dyeing method that uses carbonated water to make the process cleaner, cheaper, and easier to recycle. The innovation marks a technical advance in polyester dyeing, enabling cleaner production and greater fibre recovery without additional industrial investment.
- The process, called SwitchDye, uses carbonated water to reduce the use of hazardous chemicals during polyester dyeing.
- By replacing harmful solvents and reducing the volume of wastewater, the method significantly cuts environmental impact while maintaining full colour strength and durability in finished fabrics.
- The technique eliminates the need for new dyeing machinery, making adoption straightforward for manufacturers and ensuring that existing industrial equipment remains compatible with the cleaner process.
- Developed through collaboration between the Schools of Chemistry and Design at the University of Leeds, the research strengthens links between materials science and sustainable manufacturing practices.
- It was developed as part of Dr Nathaniel Crompton’s PhD project at the university and later advanced with Dr Harrison Oates, now Chief Technology Officer of SwitchDye.
THE STUDY: Developed at the University of Leeds through joint research between the School of Design, School of Chemistry, and the Leeds Institute of Textiles and Colour, SwitchDye represents a study-led advance in polyester dyeing with clear industrial relevance.
- Professors Richard Blackburn and Chris Rayner created the original concept, which Dr Crompton developed during his PhD research, later joined by Dr Oates to form the SwitchDye team. Testing at the School of Design and the Leeds Institute of Textiles and Colour verified performance against industry colour-fastness requirements.
- SwitchDye was developed within the University of Leeds’s on-campus Nexus innovation community and functions on existing dyeing equipment, supporting straightforward industrial adoption without new machinery or retooling.
- The team demonstrated applicability beyond polyester, reporting the method also works on synthetic fibres such as nylon and elastane with no loss of colour strength or quality.
- Extensive testing at the School of Design and LITAC confirmed the dyes met or exceeded industry requirements for colour fastness, supported by research at the Priestley Centre for Climate Futures.
- Funding and support came from The Clothworkers’ Foundation, The Clothworkers’ Company, The Dyers’ Company, EPSRC, The John Lewis Partnership Circular Future Fund, and the Northern Triangle Talent Project, demonstrating cross-institutional backing for commercialisation and scale-up.
INSIDE THE CHEMISTRY: SwitchDye introduces a small amount of carbonated water into the dye bath, which alters how colour molecules interact with polyester fibres. This “switching” behaviour allows dyes to enter and exit fibres more efficiently, reducing reliance on toxic auxiliaries and large water volumes. The method simplifies colour removal, supporting textile recycling while maintaining existing industrial workflows and equipment compatibility.
- The introduction of fizzy water changes the dye’s solubility and bonding dynamics, enabling reversible attachment without additional chemical agents or temperature extremes.
- Colour can be stripped or reapplied quickly using the same process, extending fabric life and easing closed-loop recycling for polyester garments.
- The system requires no new infrastructure, meaning mills can integrate the cleaner technology into production lines without costly downtime or retraining.
- The simplified dye-bath composition lessens treatment burden on wastewater facilities, cutting resource demand and residual toxicity in effluent streams.
WHAT CHANGES: SwitchDye directly tackles one of the textile industry’s largest sustainability challenges—chemical discharge and water waste from dyeing synthetic fibres. By making dyes easier to insert and remove, the method improves recyclability and lowers the pollution footprint of polyester production. The approach helps create a circular textile model by supporting fibre reuse, conserving freshwater, and reducing hazardous waste streams.
- Polyester dyeing contributes approximately 20% of global clean-water contamination, a problem SwitchDye aims to mitigate through reduced chemical use.
- The ability to remove colour without damaging fibres makes polyester fabrics easier to recycle and reuse within existing material systems.
- Using existing machinery means that cleaner dyeing becomes immediately achievable without the capital burden of plant redesign.
- The combined savings in chemicals, resources, and wastewater treatment lower production costs and improve present operational efficiency.
SCALING AHEAD: SwitchDye’s developers plan to advance from laboratory-scale trials to full commercial validation over the next six months. The next phase will complete its first financing round, expand dye production, and test the technique on industrial-scale machines. These steps will help confirm manufacturing compatibility, attract wider industry investment, and establish SwitchDye as a viable, scalable route to cleaner polyester processing and recycling.
- The company aims to finalise early-stage funding that will enable equipment trials and larger batch dyeing assessments in partnership with manufacturers.
- Commercial testing will evaluate performance on industrial-scale dyeing machines.
- Results from these trials are expected to inform partnerships with textile producers interested in adopting low-chemical, low-water dyeing systems.
- Continued collaboration between Leeds scientists, LITAC, and funding bodies will guide future innovation in sustainable dye chemistry and textile recycling.
WHAT THEY SAID
SwitchDye could transform the textile industry by reducing its huge water use footprint and its pollution problem. Not many people know that even more toxic chemicals are used to turn brightly colored wastewater into transparent liquid. When released into freshwater, this is a secret killer that harms people, animals, and the environment. We can't solve this problem without the backing of industry, investors, and policymakers, so we’re excited to share SwitchDye publicly as we aim to scale up.
— Dr Nathaniel Crompton
Chief Executive Officer
SwitchDye
Polyester is highly durable, and straightforward to recycle, however the main issue is the color in the fabric. SwitchDye can be more easily removed from the fiber, making the clothes much more recyclable. Ultimately, SwitchDye helps to make the textile industry more circular and sustainable, in both the dyeing and recycling stages.
— Dr Harrison Oates
Chief Technology Officer
SwitchDye
Sustainable approaches to polyester dyeing are paving the way to a cleaner, more circular textile industry. This startup company is an excellent example of how EPSRC investment in training, specifically in sustainable chemistry, is not only developing leaders of tomorrow but leading to new discoveries that fuel innovation.
— Jane Nicholson
Executive Director of Research
Engineering and Physical Sciences Research Council (EPSRC)
