Index0.1 finds new home in ski boots
Salomon has a comprehensive strategy, including local recycling options, for its first ‘made to be recycled’ shoe.
Recycling 100% of a shoe or item of clothing into a new version of itself, with no added virgin materials and no loss of performance, is the holy grail for many designers. Sportswear companies the world over are pooling technical and creative talents and teaming up with chemicals and material developers to try to create products that can be completely recycled, with the desired performance.
When, in April 2019, adidas launched its TPU-based Futurecraft.Loop, many bloggers were quick to praise the 100% recyclable shoe, without realising or mentioning that only between 5% and 10% of the original shoe could find itself in a next generation because recycled TPU loses quality and needs to be mixed with virgin material. Of course, any steps towards circularity should be praised; the designs are stepping stones and Futurecraft.Loop Gen 2 was launched eight months later, with a consumer launch scheduled for Spring 2021.
Hot on its heels, and with a similar launch date, is French brand Salomon. Last autumn, it also presented a shoe with the upper and sole made from TPU, which it ground down and used for a ski boot shell. The in-house announcement was met with applause for achieving the first step to circularity, and the teams promised a consumer-ready version at the start of 2021. It has now announced Index0.1 — a shoe that is “made to be recycled” and is the result of three years’ research and development at its design centre in Annecy.
Material mix
Most shoes that are made will eventually end up in landfill, given the lack of other options. To put this into context, the US alone imported 2.4 billion pairs of shoes from the top 10 exporting countries in 2019, according to industry association the Footwear Distributors and Retailers of America. This gives an indication of the piles of unwanted shoes that mount up globally each year.
Current footwear recycling is minimal, and the systems that exist tend to be based on a crude system of shredding and separating materials, resulting in pellets of various purities. Dye stuffs are hard to filter out and the resulting granulate is not pure enough for many uses, with the granulate often ending up as carpet backing or insulation. A typical sports shoe contains around 12 materials and more complicated shoes can include up to 60 — so reducing these down to the minimum is the first step.The big difference from Salomon’s concept shoe to Index0.1 is that the upper is now made of recycled polyester rather than TPU, for “durability and comfort” reasons. The upper will be recycled back into fibre and used to weave more fabric. The midsole and bottom are still TPU, which can be shredded and remoulded.
A significant hurdle for recycling is the lack of companies that can offer recycling facilities for the materials. Typically, the main ones are located in Asia, which proves problematic in terms of logistics. For all companies seeking circularity, local production of materials and assembly of shoes is vital – shipping the granulate around the world will increase the carbon footprint, wiping out the environmental advantages of recycling.
Local recycling
This was one of the reasons that Salomon chose to use the TPU from the sole and the midsole of running shoes in a ski boot shell, rather than use it for similar shoes. “Most of our Index.01 shoes are, for now, going to be distributed in Europe and North America” explains Olivier Mouzin. “Our idea was to reuse the material as much as possible locally. If we wanted to reuse the material in a new shoe we would have had to ship the material back to Asia, which is not consistent with reducing our footprint. We are ready to recycle TPU in Europe because that’s already something we are doing for ski boots.”
Salomon can recycle TPU in Europe and in partnership with its factories in Asia, but it had to find solutions for polyester and TPU in North America. “Another challenge is that only brands know the composition of their product, which means they must create a collection system themselves, which can have a high cost and might not be the system with the lowest CO2 impact,” adds Mr Mouzin. “Otherwise, they would need to work together with other brands to create a collective recycling system.”
Salomon’s boot division is accustomed to working with recycled materials but the challenge was to use the base material from the Index0.1. “We realised that by doing a few adjustments and managing the dosage, we could not only maintain the quality we are used to for our alpine boots but also improve their quality,” says Jean-Yves Aldouard, a plastics expert in the boots team. It typically uses between 5% and 20% recycled materials in the boots; any more would affect the stiffness. “Georges Salomon used to say, ‘What’s interesting is not what we do today but what we do tomorrow’. By using by-products of the Index0.1 to create winter sports products, things will have come full circle.”
Wide-ranging uses
TPU has been used by the footwear industry for decades as it can be produced as a hard rubber, a soft plastic and everything inbetween but a key challenge for the midsole was finding a material that could deliver “the perfect amount” of shock absorption and rebound needed for road running. The answer was a nitrogen-infused, TPU-based foam it has called Infiniride. Proprietary rocker geometry, R.Camber, helps propel runners forward and allows them to spend less time on the ground.
The shoe also features a 9mm drop and a moulded sock liner that is made from 100% recycled EVA foam and a recycled polyester cover. A water-based glue is also used to connect the bottom unit and the upper; Salomon explained this would minimise “material contamination” and make the product easy to disassemble at the end of its life.
Colour selection
Using a single material, while having benefits for recycling, also presents drawbacks for design and performance. Adding dyes complicates the recycling process as it results in a multi-colour granulate and, even if you have mono-colour shoes, the colour will still need to be separated in the design process.
Brent James, product line manager for Salomon Road Running, feels they were not limited in terms of colour for the Index0.1 — they deliberately chose to use less dye to reduce the potential environmental harm during production. “Design, construction and materials, however, present a bigger challenge for us,” he tells us. “The key to creating a recyclable shoe is reducing the variety of materials used while designing in a way to ensure each material can be easily separated at the end of that product's lifecycle. This also addresses the fact that each different process in the construction and breakdown of the shoe uses energy, meaning the more efficient we are at each stage, the more sustainable we are holistically."
The colour does not pose a problem with the ski boots. “We mainly use recycled TPU in our black ski boots, and black is a mix of all colours,” adds Mr Mouzin. “If we want to use recycled TPU to make boots of various colours, we will have to fine-tune some things.”
Pleasant surprise
The shoes went through all the standard tests, in the labs and on the feet of runners for hundreds of kilometres, to make sure there were no performance issues, with the runners “pleasantly surprised”. “At first glance, it does not come across as a 'technical' running shoe, which we think is a good thing,” says Brent James. “Once you lace it up and take your first few steps, runners are convinced that it lives up to the performance you expect from Salomon running products. We have consistently heard that it feels light and instantly comfortable.”
When runners decide they can no longer use the Index.01, they can print a shipping label from the Salomon website and send the shoes to the closest collection centre free of charge. From there, the shoes will begin their journey towards a second life. There will be collection centres in Europe, North America and Asia. There, the product will be washed and disassembled before each material is sent for recycling locally.
Striving for circularity fits in with Salomon’s sustainability targets. It has pledged to reduce its overall carbon emissions by 30% by 2030 and will eliminate perfluorinated compounds (PFCs) across all equipment categories by 2023. There will be no PFCs in Salomon footwear by the this autumn, in gear by 2022 and in winter sports equipment and apparel by 2023. By 2025, it has said, 70% of the waste created by Salomon’s operations will be recycled or reused and the environmental performance of every Salomon product will be visible to the consumer.
“We recognise that we have to do better for the environment by creating footwear that drastically reduces its impact on the planet,” said the company’s vice-president for footwear, Guillaume Meyzenq. “By creating this concept shoe that can be recycled into a ski boot shell, we are showing that it is possible to find alternative materials to create performance footwear. It’s an exciting development that will help lead us to more sustainable footwear solutions in the future.”
Salomon admits there’s more to learn about the logistics, materials and the production process — the holy grail remains a few strides away — but the Index0.1 shows its commitment to finding solutions. “The Index, as a concept, will live on in many different products,” concludes Mr James. “We have a few surprises in the works, so stay tuned.”
While it doesn’t look like a typical performance shoe, feedback from runners state that the Index0.1 is light and comfortable.
All credits: Salomon
