San Francisco brand Allbirds has debuted a new pair of shoes made from from eucalyptus trees. Source: Forbes After knocking out a success with their beloved wool shoes, the brand came back with another eco-friendly option. But is it really eco-friendly and how does this shoe stack up compared with their original design? We asked Joey Zwillinger, co-founder of Allbirds, about this new addition. Is anyone else making a eucalyptus shoe? Where did you get the idea? Joey Zwillinger: Since the beginning, we’ve always thought of Allbirds as a sustainable material innovation company just as much as a style brand. When we started with wool, it wasn’t only about launching a new category of shoes, it was about creating a brand that was challenging the status quo and rooted in doing better things in a better way – whether that’s through the materials we use, or our B-Corp certified supply chain, we are always looking for new ways to create incredible comfort with sustainable, natural materials. The launch of Tree represents over two years of relentless work in research and product development. To our knowledge, it is the first product with commercial scale that has been made predominantly from eucalyptus pulp (a small handful of other products incorporate small amounts of eucalyptus pulp). Because of the novelty of this invention, we created more than 50 prototypes in the development of this product to arrive at a place we like to call “the right amount of nothing”. Our Tree-based upper material is the first ever to be FSC (Forest Stewardship Council)-certified. We are excited to bring about this major change in the footwear industry, and will continue to push the boundaries of what it means to be a sustainable brand in the years to come. How is the fiber processed? Any possible negative side effects? For example, the conversation around modal and bamboo is quite heated because chemicals are used to process the fibers, and sometimes in a not so eco-friendly manner. The wood is harvested from sustainably managed farms, which is then crushed into a pulp and dissolved in a solvent bath to reshape and extract the material in thread form. The solvent used in the spinning process represents one of the greatest achievements in cellulose fiber technology – 100% closed loop and highly efficient. There is heat and energy used to process pulp to fibers; however, the overall carbon life cycle of this material is a dramatic improvement over conventional materials. How does this affect the feel of the shoe? We combined the cooling sensation of this unique fiber with a three-dimensional knitting process to engineer a soft, light and breezy feel. In a nod to our Wool line of shoes, we incorporate the same castor bean oil-derived insoles, lined with our proprietary brushed merino wool fabric to elevate the comfort experience where softness matters most. Where are you getting this wood pulp from? FSC-certified farms in South Africa, harvested sustainably, with no irrigation. How is this the “most sustainable” as stated? The fiber in our Tree collection uses 95% less water, has 92% less fertilizer runoff (eutrophication), and the resulting material has half the carbon footprint. How does it stack up to cotton, which has been a popular natural material in shoes, and particularly organic cotton? Yes, these statistics compare Tencel Lyocell to conventional cotton, and are based off of a publicly available life cycle assessment. Does this material give you more freedom in terms of styling and design? The Tree range provides a different type of comfort than Wool, and with the addition of the Skipper, it’s a perfect fit for the warmer months. The new knitting process we use in this line allows us to engineer different properties like durability and breathability, and do so differently throughout the shoes.