Outerknown, Keel Labs Make a Splash by Sprucing Up Shirts with Seaweed

Keel Labs and Outerknown have bonded over a shared soft spot for the sea.

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This partnership with the eco-conscious California company marks the first commercial launch of the North Carolina-based startup’s flagship product, the seaweed-based Kelsun fiber .

“At Keel Labs, we are deeply committed to our mission of harnessing the potential of our oceans to create better products for people and the planet alike,” said Tessa Callaghan , co-founder and CEO of Keel Labs. “Working alongside a brand like Outerknown , that shares our dedication to creating a better world, and our steadfast love of the sea to bring our products to life couldn’t be more fitting.”

Outerknown first started selling the Blanket Shirt in 2016, the same year the lifestyle label was founded by pro surfer Kelly Slater and designer John Moore. The “universally loved” button down—made with sustainable materials like organic cotton and natural corozo buttons while remaining vintage soft—quickly became a best seller and remains a favorite of Slater’s.

“It’s been 10 years since we made the first one, and we are proud to be partnering with Keel Labs on the next generation of this shirt with a version made from Kelsun,” Slater said. “Working with suppliers that share our love for the ocean is a great fit for Outerknown . I’m excited to see this grow.”

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The new men’s Blanket Shirt is an organic cotton and Kelsun yarn blend that looks, feels and performs like the tried-and-tried original. The materials science company formerly known as AlgiKnit developed Kelsun as a plug-and-play replacement for the incumbent (and inefficient) materials traditionally used by the textile industry. The 100 percent biobased and biodegradable (composting after 60 days or so in the right conditions) material is made from over 75 percent seaweed biopolymer as a replacement for fossil-fuel-focused fibers. While Seaweed is one of the most regenerative organisms on the planet, absorbing carbon dioxide in the ocean akin to trees on land, Keel Labs still only sources marine meadow adhering to sustainability guidelines and in compliance with local harvesting calendars and quantities.

The Stella McCartney-approved material is a drop-in solution, compatible with existing infrastructure and built for scale. The hope, Outerknown said, is to continue growing this partnership through future products and collaborations.

“This is a pivotal moment, not just for Keel Labs, but for the industry as a whole, standing as a marker for what lies ahead when conviction, action and collaboration combine,” Callaghan said. “This garment is the first— though not last —of its kind, and we can’t wait to continue sharing the evolution and expansion of our partnership.”

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