Used tennis strings were processed into a new sheet material, which was then used across circular economy activations around the Championships.
Wimbledon · The Championships · London, UK · 2022 · Sport and live events · Design; Consultancy
Used tennis strings are a waste stream nobody has a route for. They are thin, mixed polymer and produced in quantity at a single venue each summer. The question put to Pie Factory was whether they could be turned into a usable material rather than disposed of, and if so by what process. This was research and development, not a build. The output needed to be a sheet material with predictable behaviour, suitable for use in circular economy activations around the Championships.
The work began with characterising the material. The strings are mostly nylon. Some contain, or are coated with, PVDF, polyvinylidene fluoride. That mix is the whole problem: a recycling process that assumes one polymer will not behave predictably on a feedstock that contains two. Three processes were then tested against that feedstock. Extrusion was found to be impossible with the sample. Moulding worked, but only on a single material type, which means sorting the feedstock first. Sheet pressing proved the most forgiving: it tolerated mixed behaviour in the input and still produced a usable panel. The strings were processed into a new sheet material, and the resulting material was then used across circular economy activations around the Championships.
Mixed strings made of different materials are the reason nobody has found a way to easily recycle strings in the past. The variety of materials meant we needed to try a number of different methods to process the material into a suitable end product.
This was a materials research and development project. What the project produced is a finding and a material. The finding: it’s possible to add strings into a recycled content feedstock to create a usable product. The material: 2.4m sheets which can be used around the championships. These sheets featured in kiosks and counters enhancing Wimbledon’s sustainability messaging and creating attractive features for attendees and players alike.