Wildling minimal shoes are intended to be regenerative not only in terms of foot health, but also in the way they are made. That means that the soles of Wildling shoes have to be flexible and durable at the same time – in more ways than one. An early look at the complex work involved in becoming recyclable.
It’s no secret: Our expectations of what a Wildling shoe’s sole has to be and do are (justifiably) pretty high. Our sole is designed to permit the foot to move as freely as possible, to engage its musculature, and to be unencumbered in the truest sense of the word. Advancements and improvements are all part of the process through which creativity, trial and error, and ongoing learning help to develop more resilient and more durable Wildling shoes. However, when they do eventually wear out completely so that even the Repair Center can’t do anything to salvage them, it’s time for a new pair. The way a Wildling shoe is produced and the resources that are used to produce it naturally include finding responsible resources for the soles as well as for the uppers.
On the one hand, the main priority is to provide that barefoot feeling through the flexibility of the soles, a hallmark of Wildling shoes. On the other hand, of course, a pair of Wildling shoes is designed to sustain that feeling for as long as possible. Making the sole of a pair of Wildling shoes even more durable without sacrificing flexibility in the process may sound like a paradox at first. But within the Wildling Shoes team, it’s a challenge that is eagerly accepted :)
And to make this challenge more tangible – alongside the requirements for sole longevity – two other factors come into play: low abrasion and a good level of recyclability. All three factors are interconnected.
Abrasion is the process by which tiny particles become dislodged from the sole as the shoe is used. These particles contribute to fine dust pollution, which of course is not biodegradable. Furthermore, it’s important that abrasion caused by daily use doesn’t cause the sole to disintegrate – in short, it has to be sufficiently durable. At the same time, it also has to be flexible enough to preserve the typical wearing experience that defines every Wildling shoe.
We want to use as few new resources as possible in production, while continuing to use the components that are already in the shoes for as long as possible. That’s why Wildling Shoes wants to encourage every possible and sensible way of reusing them. Nevertheless, there is a definite long-term goal: to produce new soles made from old, recycled Wildling Shoes soles.
A look at the current Wildling Shoes sole
As we move towards a regenerative product, the most recent interim result on the path to a regenerative Wildling sole (and more circularity), made by our main manufacturer in Portugal, looks like this:
40% are made of new E-SBR. This abbreviation stands for Emulsion, Styrene, Butadiene, Rubber - and is the exact name of the rubber used.
25% are composed of silica. Specifically, this is a highly moisture-binding, natural, and innocuous silica gel
20% are made of recycled/reused SBR rubber
15% are made from recycled/reused cork
We have discovered that our old soles can be completely reprocessed and incorporated into our new soles – with minimal energy and water consumption, without the formation of additional pollutants.
This piece of knowledge was no accident. A working group was established within the Wildling team, made up of staff members who each bring different areas of expertise to bear on this extensive project.
Experiments in the kitchen and beyond
One such example is Albrecht, a retired chemistry teacher. Without further ado, Albrecht got to work cleaning old Wildling Shoes soles in the dishwasher and then liquefied them in a boiling pot to find out more about the material’s properties. Together with Sabine, a trained shoemaker from the Product Team, he is in charge of material-related matters. They tackle questions like: What materials are we currently using and which ones can we replace so as to improve the sole even more overall? Or even more granular: What bio-based alternatives to the E-SBR currently in use are potentially available? The research is supported by Ulla. Then Peter comes in as a production expert, testing the materials and creating cross-connections with the Wildling Shoes material development and design departments. Because the entire matter is so complex and many factors of the project are interdependent, there needs to be one person who has an organizational overview, who documents the achievements of the project, and facilitates the exchange of information. That’s what Natalie does in her role as project manager. The whole project is driven forward both through the efforts of the working group and, in the long term, by the entire Wildling Shoes Community. Because right now, there’s an idea in the works that will allow us to take used shoes back – to incorporate worn out soles into the production of new soles. We are super excited to share some recent developments from the Sole Project with the Wildling Community here.
Illustrations: Johanna Balzer | Wildling Shoes