After decades of looking after Asian manufacturing for big brands, David Solk and Irmi Kreuzer  ploughed their resources and experience into creating a shoe in which every element has been selected for its ability to decompose – and they are looking for likeminded partners.

David Solk is frustrated with the footwear industry. Now in his fifth decade in the shoemaking business – starting at his father’s factory in England, through to co-founding an outsource company in Vietnam – he says the big brands have created a model where increasing margins have left the sector “a bit broken”. With a focus on a five- or six-times mark-up from the manufacturer, the lead times are too long, there is too much inventory, too much waste and too many markdowns, he says. “A huge barrier to change is that brands don’t make anything themselves. The industry has lost that.”

Feeling disillusioned, David and Irmi Kreuzer wanted to use their experience to show how things could be done better. Their journey together began in 1992 while both were working at adidas, where David led product development teams in Asia and helped establish operations in China and Vietnam. After nearly a decade there, he and Irmi took a leap. In 2003, they founded Shoefabrik, a production company that became a partner for more than 20 brands including Helly Hansen, On Running and Zara, offering services from concept to final production. Inspired by Patagonia’s pioneering approach in the mid-2000s, their team worked with clients to integrate more sustainable materials and processes into footwear manufacturing. But when the financial crisis of 2008 hit, priorities shifted and momentum stalled. Irmi says: “For us, it reached a point where we felt we had two choices: take a leap to help change the industry or consider stepping away from it entirely.”

This leap has landed on biocircularity – a way of approaching the shoe that takes into consideration all aspects from design to end of life – and the Solk Fade 101. Owning their own facility meant they had the ability to work flexibly, with extra research and development, and without the usual business constraints, explains David. They financed the project themselves, so they would not need to answer to backers or shareholders. “The first idea was to create a beautiful, desirable product: if consumers desire it, they will buy it, and that will lead to change,” he says. “The next important factor was that would be ultimately harmless. And that was the hardest thing. We have one rule: everything needs to be compost-capable.”

The aim was to complete the project in two years, but creating almost every element of the shoe from a biodegradable material was more difficult than they had anticipated, even with all their knowledge. It ultimately ended up taking six years. David describes it as a very long and challenging journey – “and I’m a shoe technician, so I thought I’d be able to get there faster. Being a 100% biocircular brand is difficult as even organic cotton might have softeners and finishes that aren’t biodegradable. So, it was a question of working very closely with the vendors, and those that were willing to be transparent. The challenges were so great that we ended up partnering some European vendors, even though we are based in Vietnam.”

Solk’s headquarters are now in Switzerland and, as well as the factory in Ho Chi Minh, it runs its own composting facility in Germany. “Solk is our real family name: short, distinctive and easy to say in any language. We held onto it for over 30 years, waiting for the right moment to use it for something we truly believe in,” says David.

Nature’s bounty

The Solk Fade 101 has been created with a chrome- and metal-free leather upper from a German tannery with “robust environmental management techniques”. The outsole is natural rubber and the lining is a custom-developed blend of compostable yarns and plant fibres. The laces and webbings have been made from Lenzing’s Tencel wood pulp, and the glue is partially bio-based. 

At the end of the shoes’ life, customers apply for a composting bag on the website, then the shoes will be sent to the composter in Germany, where they will be ground up and mixed with food waste, grass and other materials and turned into a pre-industrial compost slurry. All materials have been screened against more than 200 harmful substances by a third-party laboratory and tested for safe plant growth post-composting. “If someone doesn’t return their shoes and they end up in landfill, or even buried by the family dog, we want to be sure they’ll still break down safely and be ultimately harmless as well,” comments David. “We also happen to have our own farm in Germany where we can do all our own experimenting.”

He hopes their journey and model will be one that other footwear brands can learn from, or that partnerships and collaborations can help to spread the message. “You’re fighting a very big machine and mostly customers just don’t know the benefits – who searches for biocircular shoes? It doesn’t need to be a competition all the time, we love to work with other companies.” Given the opportunity to scale, the costs will also come down, he says – and the company doesn’t intend to stop at sneakers. 

“There are already shoes using some more sustainable materials on the market today. What we’re offering is a fully biocircular sneaker that is not only comfortable, but is beautifully crafted, and has elegance in its style,” he says. “We want to be a catalyst for change, but we can’t do better than the big guys, it’s impossible, I don’t have the resources. We want to show that if it can be done, maybe it should be done. And maybe we don’t need a six-times mark up for it.”

Joined-up thinking

David Solk took part in panels at the Global Fashion Summit in Copenhagen and London’s Future Fabrics Expo. He comments when it comes to footwear recycling, the big brands should not be putting the onus on recyclers and sorters to solve their challenges, but instead should approach the largest tier four vendors, that create the polyester pellets, and ask for standardisation on three or four grades of polyester. “This would allow all the brands to put a standard pictogram on the product, which would make recycling extraordinarily easy,” he comments. “The feedstock could grow much faster, and recycling could grow much faster.”

Material composition

• Upper: The upper leather is sourced from a German tannery. The leather is chrome free and heavy metal free and has undergone a compost-capable tanning process. 
•  Laces & webbings: These are made of wood pulp from sustainably harvested eucalyptus, beech and spruce trees. This yarn fibre has been certified for biodegradability and compostability in various environments. 
•  Lace tips:  Also known as aglets, these tips are made from certified compostable material and are attached by Solk’s own machine so that every lace is the right length and there’s no production waste. 
•  Glue: The partially bio-based glue has been specially tested to fit the requirements for durability and compost capability. 
•  Lining: The one-piece, knitted-to-shape   lining is a Solk-developed blend of compostable yarns and plant fibres that are 100% biobased.
•  Outsole: Pure tree rubber 

David Solk is using his know-how of shoe making to show there is a less impactful way to produce shoes, when it comes to end-of-life.
All credits: Solk

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