Experienced tennis players use 3 tennis balls per game or practice session. After this period, the balls reach the end of their life cycle. 300 million tennis balls are manufactured each year. At the moment, having no alternative to recycling, the balls end up being sent to landfills where they decompose slowly.

ISI Soles, a company based in Felgueiras, Portugal, dedicated to the production of shoe soles, studied the problem. After several laboratory tests, ecological shoe soles were developed out of recycled tennis balls. The tennis balls are crushed in a mill. A mixture is made with cork shavings -also derived from waste wine stoppers- and thermoplastic (TR), and afterwards those are injected in the sole.

“It was a challenge launched by a Dutch customer, represented in Portugal by Raul Paiva, and we accepted that challenge. Several tests were carried out, with the combination of different materials, in order to achieve a sole that meets all the requirements and chemical and physical properties. A sole that is comfortable, durable and environmentally friendly”, said Vítor Mendes, CEO of ISI Soles. The shoes are now in production at the Viago Shoes shoe factory.

Environmental concern and sustainability are crucial for ISI Soles, which adopts sustainable production principles and uses eco-efficiency as a reference for all operations carried out. An example of this is the line of Vegan soles, which received the “Peta – Approved Vegan” certification, as well as soles composed of bio-based or biodegradable raw material.

ISI Soles obtained certification for its management system integrated by the ISO 14001 and ISO 9001 standards, having been the first Portuguese shoe soles company to be recognized for the best international practice at an environmental level.