Material innovation that transforms the fashion industry
In a world grappling with the ever-growing plastic waste crisis, innovative solutions are more crucial than ever. Enter Sway, a Bay Area-based material innovation startup, spearheaded by co-founder and CEO Julia Marsh. Sway is making waves by introducing seaweed-based, home-compostable packaging, and they’re doing it by cleverly leveraging existing supply chains and forging strategic partnerships.
Sway Co-Founders Matt Mayes and Julia Marsh, Credit: Sway
From design to biology: A founder's leap
Julia Marsh, with a background in design, made a bold leap into the realm of biological materials. Driven by a desire to create packaging that not only looked good but also did good for the planet, she embarked on a journey to explore the potential of the circular economy. This led her to the remarkable world of seaweed.
“Designers are really well qualified to be founders, because we can make the impossible visible for others.”
Her approach wasn’t just theoretical—it was immersive. Julia and her team prioritized understanding seaweed’s role in marine ecosystems before scaling production. They engaged with coastal communities, researchers, and sustainability experts to ensure that their materials weren’t just biodegradable but also beneficial to ocean health.
“We started by visiting seaweed farms on the ground, talking to a lot of marine biologists, learning from the wise seaweed community.”
Growing up in the Monterey Bay, she had deep familiarity with marine environments gave her the confidence to build a business around seaweed while ensuring that Sway’s supply chain aligned with responsible aquaculture practices.
Credit: Sway
Why Seaweed? Nature's sustainable solution
One of Sway’s flagship innovations is its seaweed-based polybag, a sustainable replacement for the billions of plastic polybags used in industries like fashion and e-commerce. Every year, 180 billion plastic polybags are produced and discarded, often after a single use. Sway’s Thermoplastic Seaweed Flex (TPSea Flex™) material offers an alternative that is durable, flexible, and home-compostable.
Credit: Sway
Seaweed isn't just a trendy ingredient, it's a powerhouse of sustainability. It's abundant, regenerative, and has the remarkable ability to absorb carbon. Sway's patented products, made from seaweed-based pellets, match the performance of conventional plastics but decompose into healthy soil after use.
Credit: Sway
"We are totally enraptured with seaweed," Julia shares. "It comes from nature, and it returns to nature." Sway's materials harness a renewable marine resource that grows without fresh water, fertilizers, or pesticides.
Seaweed contains natural polymers that make it stretchable and durable, mimicking the strength of plastic while remaining compostable.
Credit: Sway
One of Sway’s latest projects takes this commitment even further by incorporating sargassum, a type of seaweed that has become an ecological and economic challenge in the Caribbean. The Great Atlantic Sargassum Belt, a floating mass of seaweed stretching over 5,000 miles, has caused significant disruptions to marine ecosystems and coastal communities. Rather than seeing it as waste, Sway is exploring how this abundant yet problematic biomass can be turned into a sustainable packaging material. "We engaged with Newlab and Invest Puerto Rico on a project where we were using the seaweed—the sargassum that's washing ashore in the Caribbean—in our products. It actually improved the performance of our material."
This breakthrough not only provides an environmentally responsible solution to a growing waste problem but also supports new economic opportunities for coastal communities affected by sargassum influxes.
Plugging into existing infrastructure
Credit: Sway
What sets Sway apart is its strategic approach to scalability. Rather than attempting to reinvent the wheel, they've designed their materials to seamlessly integrate into existing plastic manufacturing infrastructure. This means their seaweed-based pellets can be processed using the same machinery that currently produces traditional plastic films and bags.
"We're really proud of how we've been able to scale this in partnership with the traditional plastic industry," Julia says.
She points out that while consumers are eager for sustainable alternatives, many brands still struggle to align their sustainability goals with real-world implementation. Sway is bridging this gap by offering a material that is not only compostable but also scalable using existing infrastructure—making adoption easier for brands reluctant to overhaul their packaging systems.
The power of storytelling
Beyond material innovation, Sway understands that storytelling is a critical tool for driving adoption and awareness. Julia believes that decision-making is emotional, and that a compelling narrative can make sustainability feel tangible and urgent.
“It’s really important to me that people care about materials. Some of these topics—plastic manufacturing, composting—aren’t traditionally exciting. But when you tell the right story, you can make people fall in love with solutions that can change the world.”
Sway has used storytelling to great effect, from winning the Tom Ford Plastic Innovation Prize, which propelled seaweed packaging into the spotlight, to securing features in Vogue, Business Insider, and CBS.
Credit: Vogue
Their approach has also resonated with brands like Burton, J.Crew, Florence Marine X, and Prana, who are looking for innovative materials with a strong sustainability narrative that they can share with their customers.
Partnering with Florence Marine X, the eco-conscious apparel brand founded by world champion surfer John John Florence, Sway is helping brands align their packaging with their sustainability goals.
By blending science with emotionally compelling narratives, Sway is making climate innovation not just a necessity—but something people want to be a part of.
Scaling through strategic partnerships
A key driver of Sway’s success has been its partnership with EcoEnclose, a leader in sustainable packaging solutions. Known for its commitment to cutting-edge materials, EcoEnclose specializes in helping brands transition away from fossil fuel-based plastics by offering innovative, eco-friendly alternatives. By leveraging EcoEnclose’s distribution network and expertise, Sway ensures that businesses of all sizes can easily adopt compostable packaging without overhauling their supply chains.
Credit: Sway
“Once we’ve fully validated our materials with EcoEnclose, we’re better positioned to service much larger brands and packaging distributors who can really take us to the commercial scale volumes”
Sway’s partnership with EcoEnclose goes beyond distribution—it’s also about rigorous testing and feedback loops. EcoEnclose works closely with Sway’s R&D team, ensuring the material meets performance standards while maintaining its compostable and regenerative properties. This collaborative process accelerates adoption, allowing Sway’s packaging to be used by more brands, more quickly.
Sway’s seaweed-based packaging is designed to break down naturally—just like food scraps. Credit: Sway
From bootstrapping to seed round
Sway's journey from concept to reality has been fueled by a combination of bootstrapping, prize money, and strategic funding rounds. Their initial win at the Beyond the Bag Challenge provided crucial non-dilutive capital, allowing them to build their first lab and develop their initial prototypes.
"Take non-dilutive capital from a prize, if you can," Julia advises fellow startups. "It's such a good way for most startups to get their footing."
Their recent $5 million seed round, led by Third Nature, will further accelerate their growth and market penetration.
The team behind the breakthroughs
At the heart of Sway’s success is its dedicated in-house lab, where a team of scientists, material engineers, and designers work tirelessly to push the boundaries of seaweed-based innovation. Located in the Bay Area, this small but mighty team of around 10 people has developed over 400 different material formulations to perfect their thermoplastic seaweed film. "The majority of our team is R&D—engineers and scientists figuring out how to make seaweed melt and then how to do that at scale."
Credit: Sway
Sway’s lab plays a critical role in the rapid iteration and testing of new materials. With a deep focus on biological circularity, they continuously refine their formulations to improve durability, compostability, and production efficiency.
To accelerate development, Sway is exploring machine learning to analyze seaweed species, material properties, and performance data, speeding up innovation while ensuring sustainability at scale.
"There are over 10,000 species of seaweed. Machine learning can help us find the best ones faster and optimize formulations." — Julia Marsh
For those considering a move into climate tech, Julia emphasizes that every skill set is needed—from design and engineering to finance and marketing. She encourages people to engage with climate communities, network with founders, and persistently seek opportunities that align with their expertise.
“The climate industry needs everybody—financial planners, designers, engineers. It’s a call to every skill set.”
She also highlights that genuine interest and proactive engagement often lead to opportunities, sometimes before a formal role even exists. "Half the people we’ve hired came to us saying, ‘This is the future, I need to be part of it.’ Persistence and curiosity go a long way in this space."
Looking ahead: A seaweed-powered future
Sway's innovative approach to sustainable packaging is a testament to the power of collaboration, strategic partnerships, and a deep understanding of both material science and market dynamics. By leveraging existing infrastructure and fostering a collaborative ecosystem, Sway is paving the way for a future where packaging is not only functional but also regenerative.
Credit: Sway