Latest / The Manufacturing Podcast with Fexingo: Factories, Supply Chains, and Industrial Business / How a Dutch Factory Makes Sneakers from Chewing Gum
Transcript
- Lucas: Every year, about 560 billion pieces of gum are chewed worldwide. And almost all of it ends up on sidewalks, stuck to pavement, or in landfills. But a factory in the Netherlands is taking that gum waste and turning it into sneakers. Luna: Wait — sneakers made from discarded chewing gum? That sounds both gross and fascinating. How do you even collect enough gum to make it viable? Lucas: Right, the collection is actually the most creative part. There's a company called Gum-tec — they started by installing special collection boards in public spaces in Amsterdam and other Dutch cities. These boards have a playful design that encourages people to stick their gum there instead of dropping it. Luna: So it's a behavioral nudge plus a recycling stream. I've seen those boards — they look like dotted targets, almost like a game. Lucas: Exactly. Once the gum is collected, it goes to the factory. The first step is to separate the gum from any paper or metal contaminants. Then they grind it into a fine powder, and mix it with a polymer binder — typically a thermoplastic rubber — to create a new material they call Gum-Tec. Luna: And that material becomes the sole of the shoe? Is it durable enough? Lucas: Yeah, it ends up as the outer sole, and sometimes the insole too. They've tested it for abrasion resistance and slip resistance, and it actually performs comparably to conventional rubber. The material has a distinctive speckled look — like terrazzo but made from gum. Luna: I'm imagining the smell. Does it still smell like peppermint or bubble gum after processing? Lucas: Surprisingly, no. The odor gets stripped during the grinding and washing stages. The final material is odorless. But the visual texture does retain little flecks of color from the original gum wrappers and coatings — so every batch looks a bit different. Luna: That's almost like a fingerprint for each shoe. How many grams of gum does it take to make one sole? Lucas: For a typical pair of sneakers, they use about one kilogram of collected gum. That's roughly 250 to 300 pieces of chewed gum. And each collection board can capture around 20 kilograms per month in a high-traffic area. Luna: So you need a lot of boards and a lot of chewers. It feels like the supply chain is literally foot traffic dependent. Lucas: That's the biggest challenge right now — scaling the collection. Gum-tec has partnered with municipalities and event organizers, but the raw material is scattered and sticky. Compare that to, say, recycled plastic bottles, which have established sorting infrastructure. Gum doesn't. Luna: And I imagine the logistics of hauling gum — which is sticky, potentially messy — is not trivial either. Lucas: Right. They use special containers that are lined to prevent gum from sticking to the bin. And because the gum is considered a bio-waste in some places — it's not technically biodegradable, but it's organic-based — there are regulatory hoops. But they've managed to get the process certified with a European material safety standard. Luna: Honestly, if this episode was worth a coffee to you, that's the link — buy me a coffee dot com slash fexingo. We keep the show ad-free, and listener support makes that possible. Lucas: Yeah, seriously. If these conversations have moved your work forward or just made you think differently about materials, that's exactly the kind of signal that keeps us going. Luna: And we're back to that gum sole. So besides sneakers, is Gum-tec's material being used in anything else? Lucas: Yes — they've branched into shoe accessories like insoles and also phone cases. But the sneaker is the flagship. They've partnered with a few footwear brands to produce limited-edition runs. The price point is still relatively high — around 100 euros per pair — because the material is custom and the collection is labor-intensive. Luna: So it's niche. But I'm wondering about the environmental benefit. If you factor in the cleaning and processing, does it actually have a lower carbon footprint than virgin rubber? Lucas: That's a fair question. An independent lifecycle analysis hasn't been widely published, but Gum-tec claims their process uses about 50 percent less energy than producing virgin rubber of similar quality, partly because they skip the vulcanization step. And of course, they're diverting gum from landfill or from being washed into waterways. Luna: There's also the avoided cleanup cost for cities. Gum removal from sidewalks costs municipalities millions per year. Lucas: Exactly. In Amsterdam alone, the city spends about one and a half million euros annually scrubbing gum off cobblestones and pavement. So Gum-tec is essentially providing a waste management service that also generates a raw material. Luna: That's a classic circular economy win — reduce the cost of disposal, create a sellable product. But is there enough gum waste globally to make this a real industry, or will it always be a novelty? Lucas: Great question. According to some estimates, if you could capture just 10 percent of global gum consumption, you'd have about 56 billion pieces, or roughly 200,000 tons of material. That could produce tens of millions of shoe soles. But the collection infrastructure would need to scale massively. Gum-tec is currently at about 10 tons per year capacity. Luna: So they're at a pilot scale. To go big, they'd need cities to adopt collection boards as standard street furniture — and that's a capital expense for municipalities. Lucas: Right. And they'd need to compete with cheaper virgin rubber. But if carbon pricing or landfill taxes increase, the economics could flip. There's also potential to blend gum rubber with other recycled materials to reduce cost. Luna: I can see this working in urban centers with lots of foot traffic and progressive waste policies. Think London, Tokyo, New York. Lucas: Exactly. Gum-tec has already run pilot programs with Schiphol Airport and some theme parks. They're also working on a version that uses biodegradable gum — the kind made from natural chicle instead of synthetic polymers. Luna: That might solve two problems at once: the gum degrades if it ends up in the environment, and if collected, it still becomes a shoe. Lucas: Yeah. And it's interesting because the synthetic gum base is basically a rubber polymer anyway — it's not so different from what we use in tires. The challenge is convincing people that there's value in a material we've been trained to consider completely worthless. Luna: That's the core of so many recycling innovations — changing the cultural perception of waste. If this takes off, maybe we'll look at gum stains on the sidewalk differently. Lucas: Right. And the factory itself — it's a modest operation in Eindhoven, but they've shown that with the right design and partnerships, a literally sticky problem can become a pair of sneakers you'd actually want to wear. Luna: I'm curious whether other companies are imitating this model. Any competition emerging? Lucas: A few startups in the UK and Germany are experimenting with gum-based products, mostly in construction — like tiles and paving stones. But Gum-tec holds a patent on the specific milling and blending process that makes the rubber consistent enough for footwear. So they have a moat, at least for now. Luna: It'll be interesting to watch whether this stays a specialty product or if cities start seeing gum as a resource rather than a nuisance. Lucas: And that's the industrial question, really. Can you build a factory around a waste stream that's scattered and small? The answer might depend on how much we're willing to pay not to have it on our sidewalks.