Seaweed takes center stage in H&M’s new summer capsule, produced in partnership with Keel Labs. The collaboration signals a wider shift as brands explore scalable, bio-derived alternatives to synthetic fibers.
H&M’s latest venture into sustainable fashion is not another nod to recycled polyester or organic cotton. Instead, the fast-fashion behemoth is casting its gaze toward the ocean floor, where regenerative marine organisms like seaweed may hold the key to its climate goals.
Through a partnership with Keel Labs, the company has introduced a capsule made with Kelsun, a textile fiber derived from macroalgae. The launch, which uses the undyed material in relaxed, tactile summer separates, marks the first time Kelsun has been used in a high-street retail collection at scale.
“We continuously seek new technologies and materials to evolve our designs. For us, fashion and innovation are intertwined,” said Cecelia McNeil, sustainability manager at H&M. The brand opted to let the fiber’s natural hue and texture shine through without added dyes. “Using the natural colour of the fibre also felt essential, no dyeing techniques were used — the set is presented in its purity.”
Kelsun had previously made a limited debut through Stella McCartney and has since been adopted by H&M’s sister brand, & Other Stories. That earlier line, featuring a seaweed-and-organic-cotton blend, was designed by Frida Billegren, who drew inspiration from the ocean’s anemone-like forms.
The fiber itself is the brainchild of Keel Labs co-founder and CEO Aleks Gosiewski, who began developing it in 2017 while still a student. The goal was to create a viable, climate-forward alternative to synthetics and conventional cellulose textiles. “At the end of the day, our goal is simple: we want to create materials that allow fashion brands to meet their sustainability goals without compromising on quality or performance,” Gosiewski said.
Seaweed offers compelling advantages over land-based crops: it grows rapidly without fertilizer, pesticides, or fresh water, and it absorbs carbon dioxide while producing oxygen. Keel Labs’ process blends seaweed with a bio-based carrier to produce a fiber that is non-toxic, microplastic-free, and fully biodegradable. Still, cost and scalability remain hurdles. Production at commercial volumes is currently expensive, and once the fiber is blended with others, it loses its recyclability.
Yet the timing is strategic. H&M has pledged to source 30 percent of its materials from certified recycled content by the end of 2025, and 100 percent of its materials from recycled or sustainably sourced inputs by 2030. Its climate targets include reducing Scope 1, 2, and 3 greenhouse gas emissions by 56 percent and phasing in full compliance with ZDHC chemical standards.
As the material science space evolves, other brands are chasing similar innovations. At this year’s Future Fabrics Expo in London, the Korvaa Consortium unveiled a concept shoe built entirely from biological materials: a bacterial nanocellulose upper by Modern Synthesis, a 3D-printed PHA midsole by Ourobio, and a mushroom-grown sole by Ecovative. Even the laces and lining are made from lyocell and cotton. The prototype was created to demonstrate how nature-based ingredients can displace synthetic components across the full supply chain.
“Each material was chosen for what it does best — and together they show that biology can manufacture complex products that traditionally require dozens of synthetic inputs,” said Eben Bayer, co-founder and CEO of Ecovative.
Commercial application, however, remains limited. Vivobarefoot, the London-based barefoot shoe company, is among the first to bring mycelium to the retail market. Its vegan Gobi sneaker is made with HyphaLite, a material created by combining mycelium with natural latex and cellulose to mimic leather.
“We’ve always wanted to have a vegan product that’s not made from plastic, but it’s incredibly hard to find something that’s both natural and durable enough for footwear,” Charlotte Pumford, Vivobarefoot’s director of sustainability, told Forbes.
Early prototypes were prone to tearing or absorbing water, but the brand continued iterating until it achieved a material that was not only robust but also repairable. The outsole, traditionally the most petrochemical-heavy component, is now made from natural rubber, citric acid, and plant-based fillers, thanks to a collaboration with Natural Fiber Welding.
“We’re at the beginning of a materials revolution,” said Pumford. “Legislation is coming, customers are demanding more, and the science is catching up.”
She also emphasized the importance of longevity: “If a shoe falls apart after a few weeks, it doesn’t matter how sustainable the materials are. It has to last.”
Vivobarefoot’s Revivo platform repairs and recirculates used footwear, a strategy the company views as equally critical as biodegradability. Still, Pumford noted that there is currently no standardized test for biodegradability in footwear. “Even when we hit 100 percent natural materials, it doesn’t mean that it’s biodegradable at that point — it just means we have 100 percent fully natural materials in the style.”
Related on Ethos:
