This California startup is replacing plastic bags with seaweed-based packaging

An item of clothing in green seaweed packaging; a person in a teal bikini holding a bundle of seaweed on the beach, a roll of green seaweed film

Think about the last ten things you bought that arrived wrapped in plastic film, packaged into a plastic bag and shipped in another plastic bag. 

It adds up to a lot of plastic — especially that thin, protective film-like plastic — which is the hardest to replace with an eco-friendly alternative.

Difficult doesn’t mean impossible, though. And that’s where Sway comes in. 

The California-based startup, founded in 2020 by Julia Marsh, Matt Mayes, and Leland Maschmeyer, is using polymers found in seaweed to make a compostable alternative to thin-film plastic packaging. 

The company is already getting quite a bit of attention in the sustainability world. Sway was named as a winner of the Beyond the Bay Challenge in 2021, and earlier this year won first prize from the Tom Ford Plastic Plastic Innovation Prize

A man holds up a bundle of seaweed and a women holds up a roll of bio-plastic wrap. They are both smiling.
Matt Mayes and Julia Marsh, co-founders of Sway. Photo courtesy of Sway

“At Sway, we are building the next stage in the evolution of plastic. We often talk about the ‘plastic problem,’ but it is only a symptom of a much deeper dependency on petroleum,” CEO Julia Marsh said in a press release. 

“We are building a material as functional and accessible as traditional plastic, but derived from a benevolent source instead. With the regenerative power of seaweed, we plan to replace petroplastic — for good.” 

According to Plastic Oceans, about 500 billion plastic bags are used worldwide, and about 180 billion plastic bags are produced every year to store and protect clothing, shoes and accessories — all of which could take up to 1,000 years to decompose

Sway bags, however, biodegrade in just four to six weeks — faster than a corn cob, but slower than a banana peel. The product has a 12-month shelf life, and the seaweed used to make Sway products can sequester up to 20 times more carbon per acre than trees, according to a Harvard University study

Marsh is not new to the packaging world. Before founding Sway, she spent about 10 years as a brand and packaging systems designer, which she said she found to be “really at odds with my identity as an environmentalist and naturalist,” in an interview with Fast Company

A cream t-shirt and a pair of white socks in clear Sway seaweed packaging
Photo courtesy of Sway

She found seaweed to be an incredibly sustainable alternative. The company works with ocean farms that grow seaweed in spots of the ocean, so harvesting the seaweed is “like giving the plants a haircut, not pulling them out by the roots,” Marsh explained to Forbes

Seaweed grows fast and can be tweaked to form clear sheets for Sway’s plastic alternatives. 

Marsh told Forbes that Sway materials fit into existing supply chains and machines, so there’s no need for new infrastructure. 

“We’re not asking individuals to make those choices, we’re asking the corporations and brands that are most responsible for producing waste to switch to our material,” she told Business Insider. “Retail bags and poly bags are some of the most pervasive polluters of marine systems.” 

Sway’s flagship film comes in three colors and is printable and heat-sealable. It can be used for polybags, pouches, product windows, fashion and accessories, personal care, and dry goods. 

A greeting card sits among a bed of yellow flowers
Graf Lantz greeting cards are packaged in Sway's seaweed alternative. Photo courtesy of Sway

Graf Lantz greeting cards and woolen goods are sent in Sway packaging now, as are shoes from designer Alex Gray. While the product isn’t available direct-to-consumer yet, companies can submit a pilot form to partner with Sway for packaging needs. 

“The Sway team is building a material that stands out from the rest,” fund manager Jon Shulkin said in a press release. “While current offerings require brands to make painful compromises in cost, performance or true sustainability, Sway is designing products to make the plastic-free transition seamless and affordable to their customers.”

Sway isn’t the only company looking at seaweed as a plastic replacement. Investments in startups working with seaweed doubled in 2021.

Five of the eight finalists for the Tom Ford prize were using seaweed as a base. Some of the other existing alternatives for plastic have extra challenges. Forks made from corn-based plastic are difficult to compost,  for example, and require large amounts of land to grow. Seaweed farms offer coastline jobs and require no land or fertilizer to grow. 

“We believe the next generation of packaging can replenish life, from sea to soil,” Sway’s website reads. “Together, we can usher in a new age of materials — one which creates reciprocity between business and our shared planet.”

Header images courtesy of Sway/Instagram

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