How Sway is Turning Seaweed Into Plastic and Designing a More Sustainable Future

Here on planet Earth, we have a plastics problem. Estimates suggest that by 2050, there will be more plastic in the ocean than fish. And despite what we’ve been taught about plastic recycling, we know that its effectiveness as a solution is largely a myth—in the US, municipalities collect more types of plastics than they have the capability to process, and only about 5% of plastic actually gets recycled. In addition, due to the environmental and human health effects of microplastics, nanoplastics, and forever chemicals in our bodies and ecosystems, plastic chemicals such as bisphenols, phthalates and per- and polyfluoroalkyl substances are laden with an annual societal cost of $249 billion in the US and  $16 trillion globally—much larger than their actual market size!

There is some debate over the carbon footprint and environmental effects of bioplastics compared to traditional petroleum derived plastics. Concerns about bioplastics include land and water use, compostability (e.g. need for industrial facilities), and performance. However, as new sources for safely earth-digestible bioplastics (e.g. PHA, PBAT and PLA) are discovered (e.g. microbes, fungi, agricultural waste and alginates), there is less reliance on corn and other more environmentally draining sources, and the argument for bioplastics becomes stronger. Sway, which creates packaging materials from seaweed, is one of the innovators leading the charge.

Aligned with our investment theme of sustainability, Designer Fund is excited to announce our investment in Sway.

Alongside circular economy investors and biodiversity experts including Third Nature Capital, Alante Capital, and Superorganism, we’re excited to support Sway in scaling their seaweed-based, home-compostable packaging materials which match the vital performance attributes of conventional plastics and are designed to plug into existing infrastructure, enabling scale and massive impact. Unlike plastic, Sway’s materials are made from an abundant, regenerative resource and decompose into healthy soil after use.

Sway Founders
Co-founders Matt Mayes and Julia Marsh holding seaweed and a roll of Sway plastic film. Credit: Sway.

Since launching, Sway’s solutions have garnered recognition from Vogue, Condé Nast, Forbes, Business Insider, and Fast Company, and have won them the Tom Ford Plastic Innovation Prize and the Beyond the Bag Challenge by Closed Loop Partners. As a member of the Sustainable Packaging Coalition, the Sustainable Ocean Alliance, and 1% for the Planet, Sway is working holistically to scale their product for a thriving, equitable future.

We sat down with designer founder Julia Marsh to learn more behind the motivation for starting Sway, how she sees design shaping the future of sustainable packaging, and what designers can do today to contribute to a better future for the planet.

Tell us about how Sway got started. What was the inspiration?

As a designer building brand and packaging systems, I was often the person responsible for bringing plastic into the picture. I came to see that design was essential for enabling the transition to plastic-free solutions—because plastic waste is a design flaw.

After a full evaluation across all available plastic alternatives, I found very few solutions are truly “better” across the full criteria. Each one made some sort of compromise in terms of feedstock sustainability, rate of decomposition, performance, or cost—in fact, I found that many bioplastics come with their own unique consequences. I wanted to find something that was truly better.

In my pursuit of solutions, I became obsessed with the third pillar of the circular economy, which asks that we regenerate natural systems. What if replacements for plastic could actually replenish life? Despite my non-technical background, it was clear that there’s a wealth of overlooked potential solutions in nature which embody the concept of regeneration. Mycelium, scoby, microalgae, agricultural waste, seaweed—all these renewable resources can be leveraged into new innovations while giving back to ecosystems as they grow.

Julia Marsh
I came to see that design was essential for enabling the transition to plastic-free solutions—because plastic waste is a design flaw. Co-founder and CEO Julia Marsh of Sway.
Credit: Sway.

What made you want to build a materials company based on seaweed?

Seaweed really caught my attention. As a kid growing up in the Monterey Bay area, I was already very familiar with underwater forests and ocean farms. Seaweed is beautiful, diverse, and abundant. It’s also rich in natural polymers. I began researching seaweed’s suitability as a feedstock to replace plastics and found it met all of the criteria—it grows incredibly quickly, with few carbon-intensive inputs, requires no fresh water or pesticides to grow, and is available on nearly every coastline in the world.

As the vision for Sway began to crystalize, my co-founder Matt Mayes and I visited farms and scientists—even driving the pan-American highway from Berkeley to Peru to meet with seaweed cultivators. We found that seaweed farms naturally support improved water chemistry, biodiversity, and coastal communities. New science even suggests seaweed can store massive amounts of carbon.

Seaweed is the most promising source to support a material revolution. That’s why we started Sway—to use seaweed to create new materials that replace plastics.

Why does design matter to the success of Sway?

Conscious material design enables us to transform packaging from a potential pollutant into a potential source of life. Design is a critical factor in two things: enticing brands to make the switch away from plastic, given that packaging is a tangible sustainability storytelling, and delighting consumers. Making innovative new materials feel accessible and joyful will only boost behavior change at scale.

Sway Bags
Assortment of Sway Firstwave™ clear seaweed based plastic bags. Credit: Sway.

What do Sway’s customers value most when it comes to sustainable packaging?

Many brands approach Sway with the intention of finding packaging that can help reduce their carbon footprint, a goal which is being compounded by emerging Extended Producer Responsibility (EPR) legislation. But through our discovery process, brands begin to understand that the seaweed packaging story goes far beyond carbon reduction and avoiding pollution.

Seaweed is an incredible ocean crop that can purify and clean our seas, enhance underwater biodiversity, and boost coastal economies, securing climate-resilient employment for those most vulnerable to the impacts of our changing planet. Once you start to learn about the tangible benefits of seaweed, there are so many other stories to uncover—new science, frontline farmer stories, ocean health, regeneration, circularity, composting, and more.

These entry points offer valuable, inspiring, and untold narratives that go beyond the available alternatives, which help our customers and end users feel more hopeful about the future. That optimism—and a sense of impact—is incredibly important to enabling the transition to plastic-free solutions on a bigger scale.

What is your vision for Sway? What impact do you hope to have on the world?

The 10-year vision for Sway is to bring benevolent materials into the mainstream. By scaling next generation materials made from seaweed, we have the opportunity to evolve entire supply chains and drive down demand for harmful petrochemicals, while actively healing natural systems from sea to soil.

If Sway materials are ubiquitous, it means we’ve succeeded in building a global supply chain where traditional plastic manufacturers are working with seaweed and plants, instead of petroleum to make their products. Julia Marsh, Co-founder and CEO of Sway

Imagine if every polybag, pouch, and wrapper had the power to rejuvenate ocean ecosystems! If your Snickers wrapper is made from seaweed, it's supporting ocean farms and ocean health—expanding biodiversity and improving water quality, while also eliminating plastic pollution. If Sway materials are ubiquitous, it means we’ve succeeded in building a global supply chain where traditional plastic manufacturers are working with seaweed and plants, instead of petroleum to make their products.

But our work doesn’t stop there. Our vision is to not only contribute new materials to the circular economy, but also to help facilitate the mass adoption of circular practices. This includes easy access to compost infrastructure, which is impactful not just from the perspective of materials usage, but also in diverting organic waste away from landfills. We envision a future where consumption can actually feed into a cycle of biological circularity—a system nature invented eons ago!

Sway Seaweed
Seaweed experimentation. Credit: Sway.


How can designers actively contribute to sustainable and regenerative design?

Over 80% of environmental waste is determined at the design stage. Designers can wield their power and influence to make “better” materials beautiful, accessible and efficient. Finding new or novel materials and seamlessly integrating them into new products and packaging is a power uniquely influenced by the designer—one which I hope leads to meaningful impact!

Sway Labs
Sway materials team experimenting with various seaweed species. Credit: Snacktime.


We’re proud that Sway can enable more brands and product designers to create packaging with end of life in mind. We look forward to seeing Sway’s bioplastic resins and drop-in replacement materials take over traditional plastic films and become ubiquitous, from the polybag that your new sweater gets shipped in, to the wrapper of your favorite snacks. 🍫

Learn more about Sway’s latest raise and developments here.

Hero image courtesy of Sway.