As part of Slow Factory Foundation's One X One Incubator conscious design initiative, NYC streetwear brand Public School have teamed up with material scientist Theanne Schiros to biofabricate a pair of trainers made from SCOBY, a symbiotic culture of yeast and bacteria, a by-product of Kombucha Tea. This leather substitute is fully biodegradable and has a 97% lower carbon footprint than the most commonly used leather alternative, Polyurethane (PU).

Raising animals for food and leather equates to huge amounts of deforestation for feed and pastureland and consumes vast amounts of water and fossil fuels. Massive amounts of energy and dangerous chemicals are required to turn hides into leather, including; mineral salts, formaldehyde, coal-tar derivatives, and various oils, dyes, and finishes, some cyanide-based. As the appetite and pressure for more sustainable fashion have increased, it's no wonder brands are seeking leather alternatives. However, most of these alternatives are currently made from polyurethane (PU) or polyvinyl chloride (PVC), petroleum-based materials with their own environmental concern, posing problems during and after their lifespan. Taking many years to degrade, they end up in landfills leaching toxic chemicals into soil and waterways or releasing toxins into the atmosphere when incinerated. 

Public School founders Dao-Yi Chow and Maxwell Osborne paired up with material scientist Theanne Schiros to turn her experimental leather substitute material into a genuine, sought-after product. They chose trainers because of their universal appeal and the challenge they posed due to their durability requirements and the multitude of components. 

The trainers 'leather' components were biofabricated using fermented SCOBY, a waste product from a local kombucha brewery, OM Champagne Tea, New York. SCOBY is a bacterial nanocellulose (BNC) with higher elasticity and strength than commonly derived cellulose from wood pulp or cotton. It is processed using plant-based tanning and dyeing techniques to create a leather-like material in both aesthetics and material properties. To achieve the opaque black on the trainer, Public School used indigo pigment from the leaves of the titular shrub with a soy milk binder. The material could also be over-dyed with myrobalan in a logwood dye bath, eliminating the toxins used in standard dyeing processes. The SCOBY leather is dried in moulds, which eliminates waste associated with traditional pattern cutting. 

The material has a lifespan of several years but remains compostable, taking a couple of months for naturally occurring microorganisms to biodegrade it in a domestic compost heap, returning it as nutrients for a healthy ecosystem. 

"Microbes spun the material, plants and minerals coloured and tanned it, and humans designed and constructed sneakers from it," Schiros said. "By harnessing nature's strategy of using microbes to build up and break down rapidly renewable performance materials and incorporating waste-to-resource strategies, we can engineer bio-textiles that can displace extractive, petroleum-based textiles and toxic dyeing and processing." [Dezeen]

The process used by Public School is scalable for commercial production. 

Image credit: https://thisismold.com/process/materials/public-school-nys-new-bio-leather-sneakers-are-brewed-like-kombucha