How one startup wants to bring an innovative solution to the plastic bag problem
Six years ago, Julia Marsh gathered with friends in the kitchen of her small Brooklyn apartment. She’d ordered some flour-like powder derived from seaweed off the internet, and — after watching tutorial videos on YouTube — she needed help with the baking required to turn it into an environmentally-friendly, compostable plastic.
“Early on, it was purely experimental,” said Marsh. “Let’s just see what we can make.”
As she smeared a sweet-smelling goo onto baking sheets, Marsh, then a design student at the School of Visual Arts in New York City, deliberated about what temperature to set the oven. Several trials later, her first bioplastic prototypes were born.

“They were ugly,” she said, and only “kind of resembled” plastic. But these early experiments gave the Monterey Bay native the confidence to fight against the torrent of single-use plastics threatening the oceans she grew up playing beside.
In 2020, Marsh co-founded Sway, a San Leandro startup that aims to replace conventional plastic packaging, made from petroleum products, with a green alternative. This year, Sway and four fashion brands will launch their first fully compostable seaweed-based “polybags” — the clear plastic packaging that protects new garments during delivery.