The need for circularity and closed-loop systems is gaining increasing traction in the fashion industry with major commitments by many industry behemoths and increasingly scalable development. These include mechanical and chemical recycling and materials such as Econyl that are infinitely recyclable. However, the footwear industry faces a more complex set of challenges in its transition to a sustainable system, particularly with regards to disposal, recycling and post-consumer life.

It is estimated that around 20 billion pairs of footwear are created every year and approximately 300 million end up going to landfill, with a majority containing non-biodegradable materials including synthetic rubber, EVA foam, PU and PVC among others. Biological cycles of circularity raise concern as well – biodegradable materials such as natural rubber, wool and cotton can take up to 50 years to decompose in landfill conditions, releasing greenhouse gases in the process, while chrome – tanned leather and conventional dyes leach chemicals into waterways and soil systems.  

Thus, a technical circular cycle is considered optimum to ensuring a viable closed-loop system for the footwear industry. However, a number of obstacles can occur when considering recycling. One single shoe can contain 40 – 65 different components and 360 steps to be assembled. In addition, shoes are usually assembled using solvent-based adhesives such as Benzene and Toluene that are not soluble. Certain other permanent processes such as vulcanization where the upper, outsole and tape are bonded together, prevent resoleing. These factors make disassembly even harder, prompting almost every shoe ever made to be sent to landfill – a report by the Centre for SMART, Loughborough University cites that less than 5% are recycled.

Take-back programs are becoming increasingly popular, with footwear in turn being sent to second-hand markets in developing countries. This raises two areas of concern – one where local textile markets are affected with the influx of second-hand footwear into local economies and the fact that the life of the shoe is simply extended without solving the problem of its after-life.

The use of detachable components is starting to be explored and experimented with, by large companies. Stella McCartney’s Loop sneakers, for example, use a clipping mechanism instead of glue or thread, to attach the upper to the sole, similar to Lego. This allows for easy recycling at the end of life, ensuring that each component is appropriately processed according to material. Adidas have also released the Futurecraft.Loop a trainer made entirely of one material- a modified version of TPU. Using lasers instead of glue to attach the upper and sole, the mono-material characteristic enables 100% recyclability – the shoe can be ground into pellets, melted and returned to the original state again. Nike with Nike Grind have also experimented with breaking down footwear into pellets, turning them into material for flooring instead of new footwear.

Loop Trainer by Stella McCartney

Futurecraft.Loop by Adidas

Nike Grind

The Better Shoes Foundation provides guidelines that can be considered when creating footwear meant to be part of a more holistically sustainable system. These include using thread instead of glue, using water-based glues such as Renia Aquilim 315 and Irutex™ FI 4006 1K and reducing the number of distinct components, enabling easier recyclability. 

As we face greater resource scarcity in the years to come, what is undeniable is the need for a systems-wide change in design, production and post-life recovery. Greater accountability on the part of small and large companies alike to come together to find viable, scalable solutions and invest in research and innovation can propel the fashion system towards reaching all of its sustainability goals.