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Allbirds Is Making Sustainable Shoe Soles Out of Renewable Sugarcane

The proprietary technology behind its "SweetFoam" material will be made available to the entire footwear industry.
Allbirds' SweetFoam campaign. Photo: Allbirds

Allbirds' SweetFoam campaign. Photo: Allbirds

Allbirds, the San Francisco-based, sustainability-focused footwear startup, only launched two years ago, but you wouldn't necessarily know it when looking at its — pun intended — footprint across the industry. Co-founded by retired New Zealand soccer player Tim Brown and biotech engineer Joey Zwillinger in 2014, Allbirds launched with its now-ubiquitous Wool Runner, made from New Zealand superfine merino wool. Three funding rounds, an expanded headquarters and an estimated $50 million in annual revenue later, and Allbirds is now B Corp-certified, meaning it meets the nonprofit organization's rigorous standards of social sustainability and environmental performance standards. 

But Allbirds has been selective, and intentional, about its product growth. As of just earlier this week, the company only offered three silhouettes for both men and women — the Runners, Loungers and Skippers — in two varieties, its classic Wool and the newer, lighter Tree, made from eucalyptus tree fiber, which launched this past March.

On Thursday, Allbirds finally — after three years in development — adds a third sustainable material in "SweetFoam," a proprietary sole material that's derived from renewable sugarcane. The journey to SweetFoam began when the Allbirds team quickly grew dissatisfied with the range, or lack thereof, of eco-rooted, non-petroleum-based options available in shoe soles. 

"We've always known from day one that one of the weakness we've had from a sustainability perspective is the bottom of the shoes," Zwillinger told Fashionista in a cross-country phone call. "We've been working diligently this whole time to innovate something quite special. We hope it's so transformative for the industry much more broadly than just the amounts that Allbirds uses." 

When Allbirds as we know it was still in its infancy, Zwillinger and Brown began contact with a Brazilian petrochemical company called Braskem. In their initial pitch, the Allbirds team relayed their vision of creating both a brand-new polymer and subsequent foam out of sugarcane. ("We knew that sugarcane was the most environmentally responsible, self-sufficient carbon source, pretty much on the planet, that you could find," said Zwillinger.) After a courtship period, Braskem eventually signed on to help invest in and partner with Allbirds to make SweetFoam a reality. 

The physical sugarcane at the root of SweetFoam comes from dense, rain-drenched fields in Southern Brazil. In its growth, it's treated with minimal fertilizer and later, processed in facilities that are run entirely on renewable power, making SweetFoam the planet's first carbon negative EVA polymer.

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Allbirds' SweetFoam campaign. Photo: Allbirds

Allbirds' SweetFoam campaign. Photo: Allbirds

How does the sugarcane physically become SweetFoam? The sugarcane is processed in a sugar mill, during which point the purest portion is removed and sold as refined table sugar while the waste product, called molasses, is treated. From there, the molasses is put into large stainless steel tanks along with a yeast, which metabolizes the sugars within the molasses and coverts it into ethanol. Then, through a number of other chemical processes, that ethanol is translated into EVA, which Allbirds takes and mixes with a "special blend" to make the end product — SweetFoam — more comfortable. 

"The product is perfect, as far as we can see," said Zwillinger. "We work as long as we can to make sure that the product lives up to the standards we've set. We try to do a lot more with a lot less, meaning that we try to do a lot more sales of volume with very few SKUs, but make them really count."

While Allbirds is first introducing SweetFoam into its product line via its flip-flop sandal, the Zeffer, it will soon be rolled out across the soles of all its shoes. But Allbirds is also making its proprietary technology available to any company that desires it.

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"If you look at the fashion industry broadly, it's one of the largest emitters of carbon into the atmosphere. If you zoom in a little bit further and look at the footwear industry, you realize that about 20 billion pairs of shoes are made each year," said Brown. "And so, you have a small company here in San Francisco that's come in and found a solution to doing it a better way. I think as part of our mission, it's not enough just for us to use it — it's also the idea that we will make this available to the larger footwear industry and the larger fashion industry and anyone who wants to use it. This is a problem we're not going to solve just by ourselves; we're going to solve it together."

Brown compared this current momentum within footwear to the mainstreaming of the organic food movement, much of which occurred when better, more sustainable solutions became nonnegotiable across retailers and price points. 

"It is possible to innovate with materials like sugarcane and it is possible to find better solutions, if you commit to it," said Brown. "And hopefully, we can show the way and show how that's done, because we're a little smaller."

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