Keel Labs' Kelsun™ Fiber made a spectacular debut at the Spring 2025 Paris Fashion Week, integrated into a range of Stella McCartney’s designs, including striking tank tops that drew considerable attention from the fashion elite. This high-profile runway showcase marked an important milestone for the fibre, which is made from a biopolymer derived from seaweed. The collaboration with Stella McCartney, a designer known for her outspoken advocacy for sustainability, underscored Kelsun’s potential to revolutionise the industry.
Tessa Callaghan, co-founder and CEO of Keel Labs, was instrumental in steering this breakthrough partnership. "Kelsun was first shown on the runway at Paris Fashion Week in October of 2023 with Stella," Callaghan explained. "Within the luxury fashion space, Stella has been outspoken about the environmental impact of fashion for the past 15 years. She has been at the forefront of innovation, especially in next-generation materials, making her an ideal partner to showcase Kelsun."
McCartney’s long-standing commitment to sustainability made this collaboration a natural fit. The designer has continuously set bold targets for her brand, advocating for cruelty-free and circular design principles, values that align perfectly with Keel Labs' mission. Kelsun™ Fiber, designed to start with positive raw materials and end its life without harming the environment, resonates deeply with McCartney’s vision. "Stella’s goals for more circular design fit directly with our founding principles of transforming the textile and fashion industries," Callaghan noted.
Keel Labs’ collaboration with Stella McCartney continues to gain momentum. In addition to its appearance at Paris Fashion Week, McCartney showcased Kelsun™ Fiber on the runway again just last month as part of her Spring/Summer 2025 collection. Among the standout pieces was a sleek vest made from the innovative seaweed biopolymer, now available for pre-order. This garment serves as a testament to the increasing versatility of Kelsun and its seamless integration into high-end fashion, further solidifying its potential to reshape the industry.
The impact of showcasing Kelsun™ Fiber on such a prestigious stage cannot be overstated. Paris Fashion Week offers a platform that reaches a global audience of designers, influencers, and fashion enthusiasts. "To have a designer as renowned and respected as Stella present the viability and versatility of Kelsun has spoken volumes for our potential and dramatically impacted the overall perception of possibilities to come," Callaghan remarked. This exposure has not only elevated the profile of Keel Labs but also broadened the dialogue around sustainable fashion in general.
For McCartney, Kelsun™ Fiber is more than just another sustainable fabric—it's part of a larger movement towards transforming the fashion industry’s environmental impact. According to Callaghan, "Stella has taken us (and other innovators) across the globe to COP28 in Dubai, Climate Week in NYC, and to her shows in Paris with her Sustainable Market. Through these events, we've connected with trailblazing people and organisations, as well as other brands interested in pioneering work with next-gen materials."
The environmental benefits of Kelsun™ Fiber are manifold. It offers an alternative to the often destructive practices associated with land-based agriculture, such as excessive water usage, and the reliance on pesticides and fertilisers. "Seaweed is incredible on its own—it’s abundant, regenerative, and sequesters carbon," Callaghan enthused. "By using this resource, we avoid the harmful practices that come with traditional fabric production."
Kelsun™ Fiber is 100% bio-based and biodegradable, created from a seaweed biopolymer called alginate, and is free from petrochemicals. "It can safely return to the Earth at its end of life," Callaghan added. This positions Kelsun™ Fiber as a vital tool for fashion brands looking to reduce their environmental footprint. Furthermore, Callaghan sees the fibre as a gateway to a broader transformation in material sourcing. "It’s important for brands to diversify their material libraries, not only relying on a single source. Kelsun is a less impactful alternative to conventional materials that can help brands reduce their environmental impact."
Keel Labs is well-positioned to meet the growing demand for sustainable textiles, especially in luxury fashion. Kelsun™ Fiber integrates seamlessly into existing textile production processes, eliminating the need for new manufacturing facilities. "We are incorporating Kelsun into commercial mills, where brands can easily access it at scale," Callaghan said. "Because Kelsun fits into existing textile infrastructure, we can work with a diverse set of companies in a variety of regions to supply better raw material sources."
Scaling Kelsun™ Fiber has not been without its challenges, particularly given the urgency of the climate crisis. "The greatest challenge we face is implementing at the speed and scale required by both business and planet," Callaghan acknowledged. Yet, the fashion industry’s increasing focus on sustainability has provided a tailwind. "By adopting Kelsun and other next-generation technologies with conviction and commitment, the fashion industry has the opportunity to directly tackle their role in the global climate crisis."
One of the most striking aspects of Kelsun™ Fiber’s appeal is how it balances sustainability with luxury aesthetics. Callaghan pointed out that designers are often surprised by the look and feel of the material. "Designers are excited and surprised to learn that the fabric they are dealing with began as seaweed. It’s soft and similar to materials they’re familiar with, making adoption easy and the end-products equally as luxurious."
The positive reception from designers and consumers alike suggests a bright future for Kelsun™ Fiber in the luxury market. "Having a runway appearance is a glimpse into the future, showing the fashion world that next-gen materials are real, and can look and feel just like the more resource-intensive materials currently being used," Callaghan observed.
The partnership between Keel Labs and Stella McCartney shows no signs of slowing down. Callaghan expressed optimism about their continued collaboration. "Most definitely! The partnership is shaping up to be a lasting one, and we are excited for all there is to come." It seems likely that more garments and collections featuring Kelsun™ Fiber will appear in future shows, further cementing its place in the luxury fashion landscape.
But Keel Labs’ ambitions extend far beyond fashion. Callaghan envisions Kelsun™ Fiber being used in a wide range of industries, from home goods to automotive textiles. "Anywhere that textiles and fibre have an application," she said, highlighting the material’s versatility. This broad potential positions Kelsun™ Fiber as a key player in the global shift towards sustainable materials.
Looking to the future, Keel Labs aims to lead a new era of material innovation, one that prioritises environmental responsibility without sacrificing quality or performance. "We envision a future built on diversification and accessibility," Callaghan said. "The only way we can live in harmony with our planet is by expanding the resources we rely on, and removing the burdens and negative impacts that come from over-cultivating individual crops and regions."
Kelsun™ Fiber offers a unique solution in this regard, helping to decrease reliance on high-risk cultivation methods while promoting a pathway to growing the material portfolio necessary to create the products consumers know and love today. As Callaghan put it, "Kelsun offers an opportunity to build a sustainable future for textiles, transforming an industry that has historically been one of the most resource-intensive into one that can coexist with the planet."
With the support of partners like Stella McCartney and the global platform of events like Paris Fashion Week, Keel Labs and Kelsun™ Fiber are paving the way for a more sustainable and innovative future for fashion. The journey has just begun, but the runway has been set for a transformation that could reshape the industry for years to come.
