Sportswear brand Puma is conducting a two-year Re:Suede experiment, during which it piloted converting experimental versions of its classic suede sneakers into compost.
The brand says it is one step closer to launching a truly biodegradable shoe after trials in which a specially made version of its suede sneakers broke down under strict conditions.
In the Re:Suede experiment, 500 pairs of shoes were sent to testers for six months. Of those shoes, 412 pairs were returned to Puma and sent to an industrial composting facility in the Netherlands, where they were mixed with other green waste and biodegraded.
After about three and a half months, most of the leather sneakers have broken down enough to be sold in the Netherlands as Grade A compost – a high-quality compost typically used in gardens and landscapes.
What slows things down is the sole, which in the Re:Suedes is made from thermoplastic elastomer (TPE-E), a type of rubber. It takes longer than other ingredients to break down into pieces small enough to be classified as compost, about six months.
Re: Suede shoes are designed with biodegradable materials
Puma calls the Re:Suede experiment “successful,” but it’s important to note that the longer time it takes for the soles to decompose is a departure from standard operating procedures for industrial composting, so the shoes can’t just be thrown into household food waste collection points.
However, Puma hopes to launch a commercial version of the sneakers next year and incorporate a recycling program that will compost the shoes using its tailor-made process.
“While the Re:Suede cannot be processed according to standard operating procedures for industrial composting, the shoes do eventually become composted,” said Anne-Laure, chief procurement officer at Puma.
Descours said.
“We will continue to innovate with our partners to identify the infrastructure and technology required to make the process viable for a commercial version of Re:Suede in 2024, including recycling programmes.”
Its leather uppers were found to decompose under industrial composting conditions
In a report on the trial results, Puma said it would pursue a “new composting business model” to support the decomposition of shoes.
“The soles slow down this process, resulting in more composting cycles required to turn the shoes into Grade A compost, meaning they cannot be processed using today’s standard industrial composting operating procedures,” the report said.
“However, with new business models for composting and greater inputs, these standard operating procedures may change,” the report concludes. “There is a future for Re:Suede. To achieve that, we need more scale.
Puma’s Re:Suede shoes are made from Zeology suede, which is tanned using a process based on the zeolite mineral and is free of chromium, aldehydes and heavy metals. The padding and laces are made from hemp, while the lining is made from a hemp-cotton blend.
For the composting process, Puma has partnered with Dutch waste management company Ortessa. The process involves shredding the shoes and placing the pieces into a compost tunnel – a unit where temperature, humidity and oxygen levels are kept at optimal levels for bacteria to break down organic matter.
In order for decomposed shoe particles to be considered small enough to be composted, they must be less than 10 millimeters in size.
The particles are regularly filtered out and sold as compost in the Netherlands.
The remaining pieces, ranging from 10 to 40 millimeters in size, become part of the “compost starter mix” and are mixed with more green waste to continue decomposition. Ortessa estimates that the entire shoe becomes compost in about six months.
Rubber outsoles take longer to break down into compost
The Re:Suede is Puma’s second attempt at launching a compostable shoe, the first coming over a decade ago in the form of 2012’s InCycle collection.
Puma said its Basket
The sneakers are fully compostable via industrial composting and are made from organic cotton and linen, with soles composed of a biodegradable plastic called APINATbio. The series was discontinued in 2014, with its failure blamed on poor consumer demand.
While several footwear designs have been marketed as biodegradable in recent years, the stringent conditions required for them to actually break down are often not specified, or the infrastructure is not available. This can be seen as greenwashing.
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