In the heart of Leeuwarden stands Bouwurk, Arcadia 2025’s circular mienskipshûs (community house). A mienskipshûs where every centimetre tells its own story. Like the Sea Silt Ceramics walls of the shop in Bouwurk, made with unique facade tiles and silt…
In the heart of Leeuwarden stands Bouwurk, Arcadia 2025’s circular mienskipshûs (community house). A mienskipshûs where every centimetre tells its own story. Like the Sea Silt Ceramics walls of the shop in Bouwurk, made with unique facade tiles and silt glazes, both from Wadden silt. A consortium of design studio Humade, Groningen Seaports, Koninklijke Tichelaar and Deltares is jointly developing a circular chain to tackle a major nature challenge: turning excess silt into high-quality building material. How do you pull off something like that? Gieke van Lon and Lotte Dekker of Humade, and Jan Kok of Koninklijke Tichelaar, talk about courage, design, circularity and building towards a different future.
Sea Silt Ceramics started in 2019, from a clear ambition of design studio Humade: to develop, on their own initiative, a serious, scalable solution for the excess salt silt in the Eems-Dollard area. The Eems-Dollard area, on the Dutch-German border, silts up every year with sediment from the Wadden Sea, which leads to a loss of biodiversity. To restore nature, seven million tonnes of silt need to be removed every year, an enormous waste stream. At the same time, the Dutch ceramics industry imports two million tonnes of clay every year, a finite raw material.
Humade saw potential here for a win-win situation: replacing clay with Wadden silt. “We wanted to create a building block that could be a symbol for a sustainable future,” Lotte explains. “We saw that silt was being used in Groningen for dikes and land raising, and thought: could that work for ceramics too? Despite sceptical reports saying it couldn’t be done, we were convinced the material had potential. Our first 3D print tests confirmed that: it produced beautiful colours and structures.” “That was the moment we thought: this Wadden silt isn’t a waste stream, it’s a new raw material. From the start, the goal wasn’t a one-off experiment, but a serious, scalable alternative for millions of tonnes of waste,” Gieke says.
What followed was years of intensive innovation. Humade took on the role of circular chain developer, to develop the entire process, from desalinating silt to ceramic production. Besides innovating with the material and developing unique processes and recipes, they took a seat at every relevant table in the sector. That laid a solid foundation for the consortium. Lotte: “Designers are often accused of only making nice one-offs for the happy few. But we developed something that can be scalable and widely applicable. We developed all kinds of recipes with at least 70% Wadden silt and other local waste streams, such as waste from the glass recycling industry and potato starch.”
In 2022, further development took place during an artist residency as part of Koninklijke Tichelaar’s 450th anniversary, and in 2024, design studio Humade, port authority Groningen Seaports, ceramics company Koninklijke Tichelaar and knowledge institute Deltares formed a consortium covering the entire chain, from Wadden silt to ceramics. Commercial director Jan Kok of Koninklijke Tichelaar: “As a consortium, we’re using the next year and a half to two years to scale up desalination and further develop silt/clay recipes that eventually need to be made suitable for production in large volumes. Traditional clay is already thousands of years old. Silt is very different and requires specific processing to make it suitable for the ceramics industry. For industrial production, everything needs to be right: desalination, the making process, plastic properties, drying and firing processes, and so on.”
The Sea Silt Ceramics wall tiles and glazes can now be seen in Bouwurk, on the facades of the shop. The connections with Arcadia and Bouwurk were quickly made. After all, Bouwurk and Sea Silt Ceramics have a lot in common: local raw materials, circular design, collaboration and a social focus. “This wall is inspiring. It makes our unique process and product visible and tangible, in a place where lots of people come together,” Lotte says.
Jan adds: “For us, Bouwurk is a stage to show the sector and the public that innovations like this are possible.” Gieke: “We also love that in Bouwurk, the social aspects of building play an important role too. That suits us: we care not just about the ecological and economic sides of doing business, but the social side as well.”
Bouwurk is just a stopover for Sea Silt Ceramics. “Our next goal is developing ceramic facade panels,” Lotte says. “Thin shells that can be dismantled and reused. And eventually, we also want to produce multiple ceramic products.” That’s also necessary to make it affordable, Jan adds: “Scaling up is exactly what lets you optimise the process and make it profitable. Our Wadden silt ceramics shouldn’t be a niche product. The goal has always been for it to become widely applicable. We want to develop a recipe, techniques and machines that other ceramics producers can use too. So that a shift happens across the whole industry.”
That ambition fits where the construction sector currently stands. The sector faces challenges like climate adaptation, the nitrogen crisis and the housing shortage, but is also working on future-proof building. “Compared to other countries, we still build fairly traditionally in the Netherlands, but developments are picking up speed,” Jan says. “Building really is different from ten years ago. Sustainability, circularity, you see it everywhere. Our Wadden silt material fits perfectly with that. Ceramics as an outer shell can easily last a hundred years, it’s low-maintenance and holds up well against wind and weather.” It doesn’t get more sustainable than that.
Fryslân was recently named the most circular region in the world. According to Jan, that’s no coincidence: “It takes a lot of energy to set up new things, and that’s what you’re doing when you work circularly. You need courage, enthusiasm and belief to move innovations forward together. You see those qualities a lot here in the region.” Gieke adds: “What I love about our consortium is exactly the collaboration between provinces: Fryslân, Groningen, Noord-Holland, Zuid-Holland, Utrecht. Sea Silt Ceramics is a collaboration between regions that want to solve a shared problem. Ultimately, of course, we don’t just want to apply this solution in the Netherlands, but worldwide. The Netherlands is small but thinks big, and it’s exactly here that you can realise this kind of chain innovation and then apply it worldwide. Excess silt exists everywhere.” Jan: “In five years, we hope to have solved the problem in the Eems-Dollard area, and to be able to apply the solution in other nature areas facing the same issue too.”
The consortium shows that innovation can go hand in hand with craftsmanship. “It remains a craft technique,” Gieke emphasises. “But new developments actually emerge from that craft. As designers, we bring not just aesthetics, but also a critical eye and the will to challenge industries and develop new processes.” Jan: “Koninklijke Tichelaar is more than 450 years old, and really a knowledge factory: we don’t just sell architectural ceramics, but also know-how about the craft. We’re now combining that with this innovation. And that fits perfectly with our strategy of looking for alternative raw materials, like Wadden silt.”
When asked what they’re most proud of, they don’t have to think for long. Gieke: “It’s unique that we built an entire chain in four years, developed a whole procedure. Because we approached it so thoroughly and seriously, we managed to win trust and get the sector excited. As chain developers, that let us build a circular chain that didn’t exist yet.” Jan agrees: “It’s not one big Eureka moment, it’s a growing process.” Lotte laughs: “I loved it when, during the closing of our open studio in Makkum, someone came up to us who had previously written in a report that silt as a waste stream wouldn’t work. He said: ‘Why did I actually write that?’ That moment felt like confirmation that jumping in at the deep end hadn’t been for nothing.”
Their message for the sector, and everyone beyond it, is clear: “Just dare to do it,” Lotte says firmly. “We could all wait for the economy and society to change, but that won’t happen by itself. You need courage and you need to take steps yourself.” Gieke: “You have to be willing to collaborate, invest time, and keep switching between small and large scale, between testing and scaling up. That’s the only way to develop something that’s never been done before.” Jan agrees: “It takes enthusiasm, commitment and perseverance. Innovating is complicated and costs time and money, but if you see it has potential, you have to go for it.”
See the Wadden silt tiles by Sea Silt Ceramics now in Bouwurk, in front of the Oldehove in Leeuwarden. Bouwurk is open Sunday to Wednesday from 10:00 to 18:00 hours, and Thursday to Saturday from 10:00 to 00:00 hours.
This year, Arcadia is working with the Netwerk Cultuur & Natuur (Culture & Nature Network) on a development trajectory for artist Marije Dijkstra. This network brings together artists, scientists and landscape partners around one question: how can artists help us…
Arcadia is the legacy programme of Leeuwarden-Fryslân 2018, European Capital of Culture. Since 2025, Arcadia has been working within the European network ECoC Echo together with eight other cities that have held, hold, or will hold the title of European…
For the research by Arcadia and the University of Groningen, Carmen van Bruggen is exploring the strength of the mienskip (community) — the Frisian word for community spirit. She’s also looking beyond the borders of Fryslân. Because how does this…